Stomach and bowel infection: what counts in the first days

Why I am writing this

In the first hours, vomiting and diarrhoea are not a fault to be switched off. They are the way your body moves a pathogen out. My attention therefore goes to two things: the fluid, because that is where the real danger sits, and the weeks afterwards, which almost nobody asks you about.

It is half past two in the morning. You are lying on the bathroom tiles because the floor is cool and because the way back to bed looks too far.

Two hours ago everything was normal. Now your legs are shaking, your mouth is dry, and you are wondering for the third time whether you dare take a sip of water.

Many people know this night. It almost always passes. Even so it is not a small thing, because in these hours one thing counts above all, namely that enough fluid comes back.

And then there is the other group. The people whose infection was six months ago and whose gut has not been the same since. I know this pattern from many conversations. The sentence almost always comes out the same way: something has not been right since that holiday.

This article covers both. First the acute phase, then travel, then the aftermath. But before that, the part that cannot wait.

Please read first: when you do not wait

A stomach and bowel infection is usually harmless. A few signs are not. With these, a medical check belongs in the picture, and promptly rather than the weekend after:

Blood in the stool or black, sticky, tarry stool
High fever, shivering, or fever that does not settle after several days
Severe or one-sided abdominal pain, a board-hard guarding of the belly, pain on release
Vomiting with no fluid intake at all over several hours, especially in older people
Clearly less urine, very dark urine, drowsiness, confusion, a racing heart
Pressure or pain in the chest, breathlessness, cold sweat, radiating into arm, jaw or back. In rare cases nausea and vomiting can also come from a heart attack, especially in older people, in diabetes and in women
Diarrhoea lasting longer than a week or symptoms after a trip to the tropics or subtropics
Unintended weight loss, night-time symptoms that wake you, anaemia
A new, persistent change in bowel habit from around 45 to 50 years of age
Bowel cancer or inflammatory bowel disease in the family

These red flags need to be investigated and not self-treated. Outside surgery hours the German out-of-hours medical service can be reached on 116117. With clouded consciousness, with circulatory weakness, with pressure or pain in the chest or with breathlessness this is an emergency, then it is 112.

One important point right here: loperamide does not fit when there is fever or blood in the stool. Why that line is drawn so sharply, and what else speaks against it, comes further down in the text.

And one more thing that gets lost in everyday life: an acute infection is no reason to let a recommended colonoscopy, endoscopy or laboratory work-up fall through. An appointment can be moved while you are ill, but it is caught up afterwards. The infection does not make the examination unnecessary, sometimes it makes it more important.

And because this article is long, here is the map.

What is waiting for you here

The most common pathogens and their timing in hours and days
Why vomiting and diarrhoea are sensible reactions first of all
The coupled salt and sugar transport, explained in one image
The WHO rehydration solution with all four numbers, and why it was diluted
Cola and pretzel sticks, finally sorted without camp warfare
Warning signs of fluid loss and who is particularly at risk
Loperamide: the limit, and the data behind it
Why antibiotics do little in most courses
The BRAT diet examined critically, and what early refeeding shows
How long you shed, the 48 hour rule, work and nursery
Travellers' diarrhoea: what prevents, what does not, what to pack
Four routes that can remain after an infection

RCT / Meta randomised or pooled Human cohort, cross-sectional, registry Guideline consensus with systematic search Model laboratory, simulation, extrapolation

What is happening inside you right now, and who can be behind it

The first question almost everyone asks is: where did I get this from.

Usually that can no longer be established. And usually the answer changes nothing. Even so it is reassuring to know that behind the words stomach and bowel infection sits a manageable group of pathogens that differ in pace and course.

In Germany, norovirus tops the list in adults. It is the pathogen that shuts down whole floors in nurseries, cruise ships and care homes. The German S2k guideline names 78,665 reported cases in 2019, 28,511 in 2020 with the contact restrictions and 45,455 in 2022. The unreported number lies far above that, because hardly anyone sees a doctor for it.

Figures on incubation, course and shedding according to the German S2k guideline on gastrointestinal infections (DGVS, version 2.1, November 2023). The figures are ranges, not certainties for the individual case. [Guideline]
Pathogen	Until symptoms begin	Typical course
Norovirus	Hours to a few days	Fierce and mostly short, projectile vomiting in the foreground, shedding usually still 7 to 14 days afterwards
Rotavirus	One to three days	Mainly in small children, watery diarrhoea over several days, in Germany there is an oral vaccination in infancy
Campylobacter	Usually 2 to 5 days, in individual cases 1 to 10	Often cramping abdominal pain, frequently with fever, sometimes bloody. Mean shedding duration 2 to 5 weeks
Salmonella	6 to 72 hours, usually 12 to 36	Fever usually settles after 48 to 72 hours, the diarrhoea stops within 4 to 10 days. Shedding in adults averages one month
Enterotoxigenic E. coli	One to three days	The classic travellers' diarrhoea, watery, without blood, mostly self-limiting after 3 to 5 days
Yersinia	Several days	Can cause pain in the lower right abdomen and thereby resemble appendicitis, occasionally joint symptoms afterwards

What this table does not show is the distinction that matters in everyday life.

Roughly speaking there are two patterns. In the first, the problem sits in the small intestine: a lot of watery stool, little fever, hardly any blood, but rapid fluid losses. In the second, the large intestine is involved: smaller stool volumes, but cramps, fever, sometimes blood or mucus. The second type is rarer and the reason why certain medicines do not fit there.

Mechanism

Why your body throws out the water it needs

A pathogen lands in the stomach or small intestine and attaches to or enters the lining. Some produce a toxin in the process, others invade the cells.
The gut cells respond by pumping chloride into the gut lumen. Sodium and water follow. The result is a rinse from the inside.
At the same time the lining reports upwards that something is wrong. Through messengers such as serotonin and through nerve pathways, nausea and vomiting follow.
Both together shorten the time a pathogen can spend in the gut. From the body's point of view this is a sensible reaction, not a malfunction.
The price is fluid. And it is exactly there, not with the pathogen, that the real danger of the first days lies in a healthy adult.

This chain is textbook physiology and well documented in its outlines. How strongly each step is expressed with which pathogen differs considerably and is still being discussed in research.

A change of perspective

The first reflex is to stop the diarrhoea. That is understandable, but on day one it often aims at the wrong place.

A more useful question is a different one: how do I get back what is being lost right now? In the first hours the diarrhoea is not the enemy. The enemy is the balance sheet.

When a stool sample makes sense and when it does not

In a banal course that settles by itself after two days, looking for the pathogen usually brings nothing. The result arrives later than the recovery, and it mostly changes nothing about what is done.

It is different with bloody diarrhoea, with high fever, with a severe or persistent course, in people with a weakened immune system, after trips to the tropics, when an outbreak is suspected and wherever reporting duties or occupational rules apply. Then diagnostics are not curiosity but the basis for decisions.

What a stool test can achieve in the chronic case and where its limits are, I have written up in detail in Stool testing and PCR diagnostics. For the acute situation the simple sentence applies: the sample asks a question, it does not replace an examination.

And now you know why the first day is not the day of medicines but the day of fluid.

Fluid: the one thing that counts in the first 48 hours

You are thirsty, you drink water, and ten minutes later it is back out the other end. That is the moment when many people give up and say: I cannot keep anything down.

The reason for that is neither weakness of will nor chance. It sits in the way water gets from the gut into the body at all.

Mechanism

Why water alone is not enough with heavy diarrhoea

Water does not travel actively through the gut wall. It follows the salt. Where sodium goes, water goes after it.
Sodium in turn barely gets in on its own when the lining is inflamed. The most important remaining route is a transporter called SGLT-1.
This transporter works like a revolving door for two: it only takes a sodium along if a glucose molecule rides with it at the same time. Without the sugar, the door does not turn.
Plain water brings no sodium with it. It briefly fills the stomach and leaves the body again. Plain lemonade brings too much sugar and osmotically pulls even more water into the gut tube.
The solution is banal and ingenious at once: salt and sugar in a particular ratio, diluted enough that the mixture does not itself attract water.

The SGLT-1 cotransport is well studied physiology and the basis of oral rehydration, which has been in use worldwide since the 1970s.

This insight is regarded as one of the most consequential simple measures in modern medicine. An editorial in the Lancet called it in 1978 possibly the most important medical advance of the century. Whether that rank really holds is hard to measure. What is undisputed is that it has been in use worldwide ever since and that today it sits in every sachet of rehydration salt.

The WHO composition, in numbers

The German S2k guideline prints the World Health Organization formula. It is not a secret but public knowledge.

245milliosmoles per litre total osmolarity

13.5 gglucose per litre

2.6 gsodium chloride per litre

1.5 gpotassium chloride per litre

On top of that come 2.6 grams of sodium citrate per litre as a buffer. The sodium content was still 90 millimoles per litre in 1975 and was lowered to 75 in 2002. The European paediatric society ESPGHAN goes even lower at 60 millimoles per litre.

Why dilute something that works? Because in this case less was more.

Meta-analysis, 15 RCTs, n=2,397 Less salt and less sugar performed better

A team around Seokyung Hahn analysed fifteen randomised controlled trials with 2,397 children in 2001 and compared a solution with reduced osmolarity against the old WHO standard solution.

With the diluted variant, fewer children needed an unscheduled infusion (odds ratio 0.61, confidence interval 0.47 to 0.81, nine studies). Stool volume was lower, vomiting less frequent (odds ratio 0.71, confidence interval 0.55 to 0.92). Six studies looked specifically for dangerously low sodium levels. Such values occurred in three of them, with no difference between the two groups.

For you this means: the composition in the pharmacy sachet is not a random product. It is the result of a correction that was based on data.

Hahn S, Kim Y, Garner P. Reduced osmolarity oral rehydration solution for treating dehydration due to diarrhoea in children: systematic review. BMJ. 2001;323(7304):81-85. PMID: 11451782 · DOI: 10.1136/bmj.323.7304.81 [Meta-analysis, k=15, n=2397]

The stricter Cochrane version of the same question came to the same result a year later, with an odds ratio of 0.59 for unscheduled infusions and without any sign of additional risk.

Honesty at this point

Almost all these numbers come from paediatrics

The German guideline itself states that oral rehydration solution has been studied almost exclusively in paediatrics. In the same paragraph it states that the results can be transferred to adult patients without restriction. That transfer is therefore professionally backed, but it does not rest on separate studies in adults.

That changes nothing about the recommendation, because the physiology of the transporter is the same in adults. It does change the tone, though. Anyone who tells you it is all proven has not read the studies.

Cola and pretzel sticks: the argument nobody needs

Hardly any topic gets such contradictory answers. One side says: absolutely not. The other: it always helped me.

The German guideline is pleasantly sober here. It states that pure fruit juices, tap water and lemonade are unsuitable for rehydration. And in the same section it says that in mild cases diluted juices with pretzel sticks or chicken broth can be sufficient.

Both together give a clear picture. Cola on its own is too high in sugar, the high sugar load pulls water into the gut osmotically. Pretzel sticks on their own bring sodium, but no fluid and no sugar in the right ratio. In combination, diluted, in a mild course, the old household rule comes surprisingly close to the principle. With real dehydration it is not enough.

A change of perspective

The question is not whether cola is allowed. The question is which situation you are in.

In a mild course, what counts above all is that something arrives at all. Then it may taste good. With heavy, watery diarrhoea the composition counts, and then a sachet from the pharmacy belongs in the glass, not a soft drink.

Mixing it yourself or buying it ready-made

The WHO composition is public, and I deliberately describe it here as a composition and not as a kitchen recipe. The reason is simple: the gap between too little and too much salt is narrower than a household scale can show, and hardly anyone has sodium citrate as a buffer in the cupboard.

A second reason comes on top: too much salt can become dangerous for children and older people, because the sodium level in the blood can rise too high. Ready-made sachets from the pharmacy hit the composition more precisely, are adapted to European conditions and cost little. For children they are clearly the preferred choice. In general, for infants and small children: they have their own rules, their own amounts and their own risk profile. This article is written for adults, and with children the assessment belongs in medical hands.

A side note for the curious: Cochrane has also looked at polymer-based solutions, that is rice water or wheat preparations instead of pure glucose. Against the old high-osmolar variant they performed better, against the modern diluted variant the advantage was small and the analysis underpowered. Cochrane rates the quality of evidence throughout as low to very low. Rice water is therefore not superstition, but not a substitute either.

Warning signs of fluid loss

Dehydration is the real danger in a stomach and bowel infection, not the pathogen. It creeps up and is often only noticed once it is already marked. Watch for these signs in yourself and in the people you are caring for:

Hardly any urine, or none at all over many hours
Very dark, concentrated urine with a strong smell
Dry mucous membranes, a sticky mouth, hardly any saliva, no tears
Standing skin folds: if you lift the skin on the back of the hand, it stays up briefly instead of springing back
A racing heart, dizziness on standing up, cold hands and feet
Drowsiness, confusion, unusual sleepiness, especially in older people
Marked weight loss within a few days, that is almost always water

Several of these signs together are a reason to get help now and not to wait until tomorrow. Outside surgery hours the German out-of-hours medical service can be reached on 116117. With confusion, with circulatory weakness, with clouded consciousness or when nothing at all can be drunk over hours, this is an emergency: call 112.

Who should pay particular attention

Seven groups in which the threshold lies lower

Older people: The sense of thirst declines with age, and so does kidney reserve. Dehydration here often shows first as confusion or as a fall, not as thirst.
People with heart or kidney disease: Both organs react sensitively to swings in volume. Here it is not only about too little, but also about the right amount. That belongs under medical supervision.
People with diabetes: Vomiting and diarrhoea throw blood sugar and insulin requirement out of order. In type 1 diabetes this can quickly become a serious metabolic situation. No insulin is left out because of it, but the situation belongs in a medical conversation.
Anyone taking fluid-reducing medication or blood pressure drugs: Diuretics, ACE inhibitors, sartans and some diabetes medicines act on exactly the control loops that are meant to counterbalance fluid loss. None of this is changed on your own, every adjustment belongs in medical hands, and promptly rather than later.
People with a weakened immune system: After transplantation, under chemotherapy, under immunosuppressive therapy, infections more often run severe and long. Here investigation and treatment start earlier.
Infants and small children: Relative to body weight they lose fluid far faster than adults. Their own rules, their own amounts and their own preparations apply. That assessment belongs in medical hands and not in a guide article.
Pregnant and breastfeeding women: In pregnancy a loss of fluid can become a problem faster, and persistent vomiting can also have causes other than an infection. Beyond that, every remedy against diarrhoea or nausea needs its own assessment here, because not everything that otherwise comes into question fits in this time. Please ask earlier than usual, and take nothing on your own initiative.

This list does not replace an examination. It is meant to help you ask earlier rather than later.

The sentence I would remember

Nobody wins a prize for bravery in a stomach and bowel infection. The course does not get better because you tough it out, but because something arrives in small sips. One sip every few minutes beats a large glass that comes straight back up.

And now you know why the first tool in that night is not a medicine but a glass with the right mixture in it.

What you can give and what you had better leave alone

At some point that night you are standing in front of the medicine cupboard. There is an opened packet from the last trip, and you are wondering.

I understand the impulse. Even so a short moment of thought pays off here, because of all things it is the most obvious remedies that have the clearest limits.

Loperamide: the limit is sharp, and it has a reason

Loperamide slows bowel movement. The stool stays longer, more water is recovered, the trips to the toilet become less frequent. For the train ride home or for an important appointment that can make the difference.

The German S2k guideline puts it cautiously: loperamide can be used in adults with acute gastroenteritis without fever and without blood in the stool for under 48 hours. For children the statement is different and clearly stricter: in acute gastroenteritis in childhood it should not be used.

Why this firmness? Because there are data on it, and uncomfortable ones.

Retrospective cohort, n=278 children What can happen with bloody diarrhoea

A team around Beth Bell looked back at 278 children under 16 who had a confirmed infection with Escherichia coli O157:H7 during a large outbreak in the US state of Washington.

37 of these children, that is 14 per cent, developed haemolytic uraemic syndrome with kidney failure and changes in the blood count. In the analysis with several variables, giving motility inhibitors in the first three days of illness was associated with an almost threefold risk (odds ratio 2.9, confidence interval 1.2 to 7.5). Even in the children without this complication, bloody diarrhoea lasted longer under motility inhibitors.

For you this means: the rule against loperamide with fever and blood in the stool is not a cautionary phrase. It stands on numbers from a real outbreak.

Bell BP, Griffin PM, Lozano P, Christie DL, Kobayashi JM, Tarr PI. Predictors of hemolytic uremic syndrome in children during a large outbreak of Escherichia coli O157:H7 infections. Pediatrics. 1997;100(1):E12. PMID: 9200386 · DOI: 10.1542/peds.100.1.e12 [Cohort, n=278]

The thought behind it is simple: if a pathogen or its toxin is in the gut and you slow down the removal, both stay there longer. With an invasive pathogen this can turn into severe distension of the bowel, the so-called toxic megacolon.

Fairness requires saying that a smaller Japanese investigation after a different outbreak did not find this association. On safety questions I follow the larger and methodologically better work. That is a judgement call and not a certainty, and I would rather say it openly than keep quiet about it.

Loperamide: the situations in which it does not fit

Fever. A febrile diarrhoea points to invasive involvement of the bowel wall.
Blood or mucus in the stool. The same argument, only more visible.
Diarrhoea during or after a course of antibiotics. Clostridioides difficile colitis can be behind it, and it can run without blood and without high fever at the start. That is exactly where a motility inhibitor can make things worse. More on this in Clostridioides difficile and colitis.
Suspected bowel obstruction, or a distended, tender belly with no passage of wind.
Inflammatory bowel disease in a flare, for example ulcerative colitis.
In children. Here the guideline statement is explicit and not softly worded. In self-medication loperamide is in any case only intended from twelve years of age.
In pregnancy and breastfeeding without medical advice.
Over several days. The guideline names a limit of under 48 hours. Anyone who needs longer does not need a higher dose but a medical assessment. With a marked overdose, severe cardiac arrhythmias have also been described.

Loperamide is pharmacy-only. Read the package leaflet, look at the contraindications and interactions, and ask at the pharmacy before you take it.

As an alternative the German guideline names racecadotril. It does not slow bowel movement but can dampen the release of fluid into the gut. In Germany the substance is prescription-only or pharmacy-only depending on the preparation, and rare but serious hypersensitivity reactions with swelling of the face and throat have been described. In German everyday practice it plays a small role in adults, and the comparative data against loperamide are modest. I mention it for completeness, not as a recommendation.

The guideline is clear about a whole group of household remedies: Uzara, dried apple powder, tannin, medicinal charcoal, healing clay and myrrh should not be used in acute gastroenteritis. That is a strong recommendation, and it comes not from sceptics but from a professional society that knows these preparations well.

Bismuth, or: why international guides run into a void here

If you read English language travel medicine, you stumble immediately over bismuth subsalicylate. The American professional society even places it ahead of loperamide in mild diarrhoeal illness.

The classic study on it dates from 1987 and found clearly less diarrhoea on the higher dose than on placebo in 182 US students in Mexico. I deliberately give no percentages here, because the substance is not available in Germany at all and a figure without a way of obtaining it only creates pressure. The German guideline states exactly that explicitly, and it is the practically most important piece of information about this substance.

Something else matters too, and it often gets lost in English language guides: this is a salicylate. It therefore does not fit with salicylate intolerance, not alongside blood thinning medicines or long-term treatment with acetylsalicylic acid, and not in children and adolescents with a febrile infection, because the rare but dangerous Reye syndrome has been described there. The most common harmless side effect is blackening of tongue and stool. That English language guides name the substance first therefore does not get you any further in Germany.

Antibiotics: the numbers instead of the claim

One thought comes up especially often on this topic: if it is bacteria, surely an antibiotic is needed.

The answer is more differentiated, and in both directions.

Meta-analysis, 11 RCTs Campylobacter: a little more than a day

A Swedish team around Anders Ternhag pooled eleven randomised controlled trials in which an antibiotic was tested against placebo in campylobacter infection.

Symptom duration shortened by an average of 1.32 days (confidence interval 0.64 to 1.99). Because of the resistance situation, the authors explicitly advise restraint in uncomplicated courses.

For you this means: one day better sooner, in exchange for the full side effect profile and a contribution to resistance development. In a severe course this calculation looks different, which is why it is decided medically and not by feeling.

Ternhag A, Asikainen T, Giesecke J, Ekdahl K. A meta-analysis on the effects of antibiotic treatment on duration of symptoms caused by infection with Campylobacter species. Clin Infect Dis. 2007;44(5):696-700. PMID: 17278062 · DOI: 10.1086/509924 [Meta-analysis, k=11]

Cochrane review, 12 RCTs, n=767 Salmonella: no gain, but longer shedding

A Cochrane team around Ifeanyi Onwuezobe analysed twelve randomised studies with 767 participants on symptomatic salmonella enteritis, antibiotic against placebo or against no antibiotic therapy.

For diarrhoea after two to four days and after five to seven days no difference showed up, the mean difference in diarrhoea duration was zero days. The context belongs with it: the figure for days two to four comes from a single study with 46 participants and is rated by Cochrane as very low quality evidence. In exchange, continued shedding of the same serovar after one month was almost twice as likely under antibiotic therapy (relative risk 1.96, confidence interval 1.29 to 2.98). Non-severe side effects occurred more often.

For you this means: in healthy adults with an uncomplicated course, the antibiotic brings nothing here and can even prolong shedding. For very young, very old, severely ill or immunosuppressed people the evidence is unclear, and that is exactly why this decision belongs in medical hands.

Onwuezobe IA, Oshun PO, Odigwe CC. Antimicrobials for treating symptomatic non-typhoidal Salmonella infection. Cochrane Database Syst Rev. 2012;11(11):CD001167. PMID: 23152205 · DOI: 10.1002/14651858.CD001167.pub2 [Meta-analysis, k=12, n=767]

Important, so that nothing is misunderstood here

This restraint is a statement about the indication, that is about the question of when an antibiotic is started at all. It is not a statement about a therapy that is already running.

If someone has prescribed you an antibiotic, it is not stopped, shortened or halved because of a blog article. None of this is changed on your own, every adjustment belongs in medical hands. If you have doubts, the right address is the prescribing practice, not the medicine cupboard.

Probiotics in the acute phase: here the guideline has good reasons

Now comes a point where you might expect something different from an integrative practice.

In recommendation 2.7 the German S2k guideline speaks out, with a strong recommendation and strong consensus, against using probiotics in acute gastroenteritis. And I find that reasoning convincing, which is why it stands here in full.

Cochrane review, 82 studies, n=12,127 The large collection found no effect

A Cochrane team around Shelui Collinson analysed eighty-two studies with 12,127 participants in 2020, of whom 11,526 were children and only 412 adults.

At the core of the analysis, that is in the two studies at low risk of bias with 1,770 participants between them, the risk of diarrhoea lasting at least 48 hours did not differ (relative risk 1.00, confidence interval 0.91 to 1.09). The 82 studies and 12,127 participants are the whole review, not the basis of this one figure. No robust statement was possible on diarrhoea duration, the confidence interval ranged from 29 hours shorter to 12 hours longer. The same applied to Lactobacillus rhamnosus GG and Saccharomyces boulardii. The funnel plots showed publication bias, meaning that studies without an effect were published less often. In fairness it belongs here that the length of hospital stay was on average shorter under probiotics, although with very large differences between the studies.

Cochrane itself words it carefully: probiotics probably make little or no difference to how many people have diarrhoea for longer than 48 hours, and whether they shorten the duration remains uncertain. For you this means: anyone claiming that a probiotic shortens an acute stomach and bowel infection is arguing against the largest and cleanest summary that exists on it.

Collinson S, Deans A, Padua-Zamora A et al. Probiotics for treating acute infectious diarrhoea. Cochrane Database Syst Rev. 2020;12(12):CD003048. PMID: 33295643 · DOI: 10.1002/14651858.CD003048.pub4 [Meta-analysis, k=82, n=12127]

Behind it stand, among others, two large randomised studies from 2018. In one of them, 971 children between three months and four years of age in ten American paediatric emergency departments received Lactobacillus rhamnosus GG or placebo for five days. Median diarrhoea duration was 49.7 versus 50.9 hours. No difference in vomiting, none in nursery days missed, none in transmission within the household.

A change of perspective

This is not a rejection of probiotics as a whole. It is a rejection of one very specific question.

Treatment in the acute case and prevention while travelling are two different questions with two different bodies of evidence. In the acute case there is no effect. In travel prevention it looks different for one single strain, more on that further down. That is not a contradiction, that is precision.

Everything about choosing preparations, about the spore form and the capsule is in its own article Probiotics: spore form or capsule. Here it is only about the acute question.

And now you know why the medicine cupboard may usually stay closed that night.

Building food back up: the BRAT diet examined critically

On the second day a hesitant hunger appears. And immediately the uncertainty: am I allowed yet? And if so, what?

The most widespread answer is BRAT. The abbreviation stands for banana, rice, applesauce, toast. It sounds like a concept, but is above all a memory aid from paediatrics.

The four foods share a logic: little fat, little fibre, plenty of easily digestible starch, plus some pectin and potassium from the banana. As a starting point that is not wrong.

As the only food over several days it is thin. Hardly any protein, little salt, hardly any fat, very few micronutrients. The combination has never had an evidence base of its own. It is clinical tradition, not a study result, and that is exactly how it belongs classified.

More interesting is the question that comes before it: do you have to wait at all?

Cochrane review, 12 RCTs, n=1,283 Eating again early did no harm

A team around Germana Gregorio compared twelve randomised studies with 1,283 children under ten in a Cochrane review. Early meant during or immediately after the start of rehydration, late meant 20 to 48 hours afterwards.

No difference was found in unscheduled infusions, none in vomiting, none in persistent diarrhoea and none in length of hospital stay. On diarrhoea duration itself no statement was possible because the differences between the studies were too large.

For you this means: the old rule of eating nothing at all for the first 24 hours has no basis. As soon as food is imaginable again, nothing speaks against it.

Gregorio GV, Dans LF, Silvestre MA. Early versus delayed refeeding for children with acute diarrhoea. Cochrane Database Syst Rev. 2011;2011(7):CD007296. PMID: 21735409 · DOI: 10.1002/14651858.CD007296.pub2 [Meta-analysis, k=12, n=1283]

The European paediatric guideline points in the same direction. It states that normal food is continued without dietary change, milk included, and that breastfeeding is not interrupted.

Milk and lactose in the first days

Here it gets subtle. Because on lactose there is a second body of evidence that points in a slightly different direction.

Cochrane review, 33 studies, n=2,973 Lactose-free food shortened diarrhoea in small children

A team around Stephen MacGillivray analysed 33 studies with 2,973 children under five, 29 of them exclusively in hospital.

Lactose-free products could shorten diarrhoea duration by an average of around 18 hours (mean difference minus 17.77 hours, confidence interval minus 25.32 to minus 10.21, low quality of evidence) and roughly halved treatment failure (relative risk 0.52, confidence interval 0.39 to 0.68). Here too the partial figure belongs with it: the 18 hours come from 16 studies with 1,467 children between them, not from all 33 studies with 2,973 children.

For you this means: the thought behind the temporary lactose problem is not invented. But these numbers come from small children in clinics, not from adults at home. For adults there is no comparable body of data.

MacGillivray S, Fahey T, McGuire W. Lactose avoidance for young children with acute diarrhoea. Cochrane Database Syst Rev. 2013;2013(10):CD005433. PMID: 24173771 · DOI: 10.1002/14651858.CD005433.pub2 [Meta-analysis, k=33, n=2973]

Mechanistically the explanation is coherent. The enzyme lactase sits right at the outside, on the tips of the intestinal villi, exactly where an infection does damage first. If this outermost layer comes off, lactase is the first thing missing, and the lactose travels on undigested into the large intestine. There the bacteria take it up, gases and osmotically active fragments arise.

In practice this means: if milk causes stomach ache in the first days after the infection, that is not a sign of a new lifelong intolerance. It is usually a transition phase lasting weeks. How to tell this apart from a real intolerance is in Lactose, fructose, sorbitol.

A practical rebuild

How I would describe getting back to eating

As long as nothing stays down: fluid only, in small sips

One sip every few minutes. Room temperature is often easier than ice cold. No pressure to eat.

Salty brothRehydration solutionDiluted tea

As soon as hunger comes: starchy, salty, low in fat

Boiled potato, rice, pasta without sauce, rusk, banana, carrot soup. Salt belongs there explicitly.

PotatoRiceBanana

After one to two days: add protein

Egg, lean chicken, cooked vegetables. The lining needs protein for rebuilding, and BRAT provides almost none of it.

EggCooked vegetables

Then step by step back to normal food

Increase fibre slowly, raw vegetables and pulses last. Lactose and larger amounts of fat can still be hard work in this phase.

Increase slowly

This is a direction, not a protocol. There are no controlled studies on a structured rebuild after gastroenteritis in adults. What stands here is extrapolation from paediatrics plus clinical observation, and that is exactly how it is meant.

What experience shows is hard work in the first days: a lot of fat, a lot of sugar, very spicy food, alcohol and coffee. Alcohol can additionally irritate the lining and draw off fluid, coffee can speed up transit. Neither is a ban, it is a question of timing.

A change of perspective

Many people believe they have to spare the gut after an infection by asking as little of it as possible.

The gut lining renews itself every few days, and for that it needs building material. Fasting for too long tends to prolong the phase of weakness rather than shorten it. Taking it easy does not mean going without, it means the right order.

And now you know why rusk may be a beginning but is not a plan.

Transmission: how long, how within the household, when back to work and nursery

On the third day you feel better. And immediately the next question arrives, usually by message from your employer: when are you back?

That question is trickier than it sounds, because two things are constantly confused.

The difference that explains everything

Shedding is not the same as risk of transmission

Shedding means: the pathogen is still detectable in the stool. That can take weeks, long after you feel well again.
Risk of transmission in everyday life means: how likely is it that enough pathogen passes from you to another person to make them ill.
The two are connected but not the same. As long as you have diarrhoea and are vomiting, you spread large amounts and often aerosols too. Afterwards the amount drops sharply.
That is why guidelines work with a time rule after symptoms end and not with a negative test.
And that is why the sentence I am well again and the sentence I am not shedding anything any more are not the same.

The figures on this are in the German guideline. Norovirus is usually still shed for 7 to 14 days after the acute illness, under immunosuppression for weeks. Campylobacter for an average of 2 to 5 weeks. Salmonella in adults for an average of one month.

Review plus modelling Why some people shed for a very long time

A team around Meghan Milbrath reviewed the literature on norovirus shedding duration and divided people into two distributions, regular shedders and long-term shedders.

Regular shedders averaged 14 to 16 days, long-term shedders 105 to 136 days. In the transmission model these few long-term shedders raised the reproduction number by 50 to 80 per cent and the outbreak probability by 33 per cent.

For you this means: a negative or positive test says less about how risky you are in everyday life than you might think. The modelling part is a simulation and not an observation in humans, and that belongs said.

Milbrath MO, Spicknall IH, Zelner JL, Moe CL, Eisenberg JNS. Heterogeneity in norovirus shedding duration affects community risk. Epidemiol Infect. 2013;141(8):1572-1584. PMID: 23507473 · DOI: 10.1017/S0950268813000496 [Systematic Review]

The 48 hour rule

The German S2k guideline puts it as expert opinion: 48 hours after vomiting and diarrhoea have ended, the risk of transmission has dropped so far that with basic hygiene there is no increased danger for family members.

And it says something else that is important: negative stool cultures as a condition for returning regularly lead to problems. Anyone who demands that keeps people away from work for weeks without creating any more safety.

Food handling occupations and communal institutions such as nurseries and schools follow their own rules under the German Infection Protection Act, plus reporting duties for certain pathogens and for clustered cases. If you work in catering, in food processing, in a care facility or in a nursery, the general rule does not apply but the requirement of your public health office and your employer does. Ask there before you go back.

Hand washing versus hand disinfection

For some years now there has been a dispenser with alcohol gel in every entrance. With norovirus that is a problem, because the virus has no envelope and alcohol acts on exactly that.

Fingerpad model, RT-qPCR Soap clearly beat the hand gel

A team around Pengbo Liu applied real Norwalk virus to human fingerpads and compared antibacterial liquid soap, alcohol-based hand gel and plain rinsing with water.

The liquid soap reached a reduction of 0.67 to 1.20 log steps, plain water rinsing 0.58 to 1.58, the alcohol-based hand gel only 0.14 to 0.34. In suspension tests, sodium hypochlorite from 160 ppm brought the signal below the detection limit, while ethanol remained weak regardless of concentration.

For you this means: hand gel is no substitute for water and soap with norovirus. What was measured here was viral material by PCR and not infectivity itself, but the direction is unambiguous and fits the official hygiene recommendations.

Liu P, Yuen Y, Hsiao HM, Jaykus LA, Moe C. Effectiveness of liquid soap and hand sanitizer against Norwalk virus on contaminated hands. Appl Environ Microbiol. 2010;76(2):394-399. PMID: 19933337 · DOI: 10.1128/AEM.01729-09 [In vitro]

What can practically help in the household

Wash rather than spray. Water, soap, at least twenty seconds, do not forget between the fingers and the nails. Then dry with your own towel.
Own towel, own flannel for the person who is ill, changed daily.
Wipe surfaces with an agent declared virucidal: door handles, the flush button, the tap, light switches, the phone. The usual antibacterial cleaners are not enough against norovirus.
Wash laundry hot, at least 60 degrees, better with a full-strength detergent. Do not leave bed linen and towels lying on the floor in between.
A separate toilet if possible, otherwise use the bathroom last and wipe afterwards. Close the lid before flushing, because flushing sends droplets upwards.
No shared eating from the same plate, and the person who is ill does not cook for others during this time.

The infectious dose for norovirus is considered very low, in investigations very small amounts of virus were already enough. That is why an outbreak in a family is more the rule than the exception, and why the effort with the surfaces really is worth it.

And now you know why a test does not clear you, but two days of rest and proper hand washing carry you quite far.

Travellers' diarrhoea: what prevents, what does not, what to pack

Third day of the holiday, and you are sitting in the hotel bathroom instead of on the beach. You go through everything you have eaten and look for the mistake.

I have to disappoint you at this point. The mistake was probably not yours.

15 to 50 %illness rate in tropical Africa and South Asia

8 to 15 %Central America, China, the Caribbean

3 to 5 daystypical duration, mostly settling on its own

These figures come from the German S2k guideline, which assumes around 40 million cases worldwide per year. The illness usually appears in the first week of travel. Dysenteric courses, that is with blood and fever, make up less than 10 per cent.

The uncomfortable finding on the hygiene rules

Everyone knows the mnemonic: boil it, peel it or forget it. It sounds sensible. It just carries considerably less in studies than hoped.

Review article, single author Seven of eight studies found no link

David Shlim reviewed all investigations that had tested the link between personal hygiene measures or food choice and the occurrence of travellers' diarrhoea. This is a critical read-through by a single author and not a systematic meta-analysis. It summarises what eight investigations found, and the result is remarkably clear all the same.

Seven of eight studies found no link between the type of food chosen and the risk of falling ill. The eighth found a lower risk with a few dietary lapses, and more lapses did not raise the risk further.

For you this means: the rules work where you control the kitchen yourself. You cannot influence the hygiene in a foreign restaurant kitchen, however disciplined your ordering is.

Shlim DR. Looking for evidence that personal hygiene precautions prevent traveler's diarrhea. Clin Infect Dis. 2005;41 Suppl 8:S531-S535. PMID: 16267714 · DOI: 10.1086/432947 [Review article]

That is not a free pass. Raw water, ice cubes of unclear origin, buffets kept warm for hours and raw seafood remain the most common routes. But it takes the self-blame out, and it explains why very careful travellers get ill too.

A risk factor that is rarely named

Anyone who dampens stomach acid lowers a barrier

The German guideline explicitly names reduced gastric acid secretion as a risk factor for travellers' diarrhoea, for example under proton pump inhibitors or after stomach surgery.

That fits an observation that accompanies me in practice: the stomach is the first border control of the digestive tract, and an acidic pH does a large part of the work before anything even reaches the small intestine. Anyone who dampens this control could let more pass through.

From this it expressly does not follow that a prescribed acid blocker should be stopped on your own before a trip. There are good reasons for these medicines. It is worth discussing medically before a long-haul trip whether the prescription still fits. More on this in Low stomach acid and betaine HCl.

Probiotics for prevention: here it looks different from the acute case

Further up it said that probiotics show no effect in an acute infection. For travel prevention the evidence is different, and that is not a contradiction but a different question.

Meta-analysis, 6 RCTs of 12 in the review One strain with a signal, the others without

In 2007 Lynne McFarland found a pooled relative risk of 0.85 for probiotics in preventing travellers' diarrhoea in a first meta-analysis of twelve randomised, blinded studies.

Twelve years later she analysed again together with Shan Goh, this time separated by strain. Twelve randomised studies went into the systematic review, and only six of them with nine treatment arms into the actual calculation. For Saccharomyces boulardii CNCM I-745 a signal showed up as the only one of the preparations examined, the risk of falling ill could be lower with it (relative risk 0.79, confidence interval 0.72 to 0.87). For Lactobacillus rhamnosus GG there was only a trend, for Lactobacillus acidophilus no effect.

Important alongside this, and it is missing from almost every text on the topic: in Germany this yeast is a licensed medicine and not suitable for everyone. With a weakened immune system and with an indwelling central venous catheter it should not be taken, because fungal bloodstream infections have been described in such situations. Whether it comes into question for you is something to clarify medically or at the pharmacy before you take anything with you. As with many probiotic papers, it is also worth looking at the conflict of interest statement in the original work, just as I do with the CdtB study further down.

For you this means: probiotics is not a category that can be judged as a whole. One strain has data here, the others do not. Which preparations exist and how quality can be recognised is in Probiotics: spore form or capsule.

McFarland LV. Meta-analysis of probiotics for the prevention of traveler's diarrhea. Travel Med Infect Dis. 2007;5(2):97-105. PMID: 17298915 · DOI: 10.1016/j.tmaid.2005.10.003 · McFarland LV, Goh S. Travel Med Infect Dis. 2019;27:11-19. PMID: 30278238 · DOI: 10.1016/j.tmaid.2018.09.007 [Meta-analysis, 6 RCTs of 12 in the review]

Antibiotics for prevention: effectiveness is not the point of dispute

Now comes the part where German and American texts part ways. And it is worth looking closely, because both sides have arguments.

There are data on effectiveness, and they are not bad. I deliberately give no percentages here. Both substance groups are prescription-only in Germany, and an efficacy figure without its counterpart is misleading.

What belongs here instead: in Germany rifaximin is not licensed for the prevention of travellers' diarrhoea. Such a use would be off label and would come with its own duty of explanation and its own liability. Fluoroquinolones have not been licensed for this purpose since a 2019 decision by the German regulator BfArM, and the reason for that is not a lack of effect. The reason is severe and in part lasting side effects affecting tendons, muscles, nerves and blood vessels, up to tendon ruptures and damage to the main artery. What comes into question for you is decided in a travel medicine consultation and not in a blog article.

Even so, in recommendation 5.13 the German S2k guideline says, with a strong recommendation and strong consensus: antimicrobial chemoprophylaxis of travellers' diarrhoea should generally not be carried out.

The seven reasons of the guideline

Why effectiveness alone is not enough

Harder follow-up treatment: If prevention fails, treating the diarrhoea that then appears becomes more difficult.
No cover against viruses and parasites: An antibiotic hits bacteria. A considerable share of travellers' diarrhoea goes back to other pathogens.
A false sense of security: Anyone who feels protected pays less attention to water, ice and food.
Side effects including Clostridioides difficile: Every dose of antibiotic changes the gut flora and can be followed by a severe colitis.
Induction of resistance: Millions of travellers taking prophylaxis are a driver of global resistance development.
Better cost effectiveness of targeted treatment: Treating when it becomes necessary is cheaper and more economical than preventing in everyone.
Missing immune response: Anyone who prevents the encounter entirely also builds no partial immunity.

On top of that comes the licensing situation: since a 2019 decision by the BfArM, fluoroquinolones are no longer licensed in Germany for prophylaxis of travellers' diarrhoea. The international travel medicine guideline from 2017 is somewhat more open at this point and leaves room in individual cases with particular risk. Both positions are reasoned, for Germany the German ruling applies.

And then there is one more finding that makes the German restraint very vivid.

Prospective cohort, n=430 In South Asia four out of five, once antibiotics were involved

A Finnish team around Anu Kantele examined stool samples from 430 travellers before and after trips outside Scandinavia.

Overall 21 per cent returned with ESBL-producing gut bacteria, that is with organisms that make many common antibiotics ineffective. Without travellers' diarrhoea and without an antibiotic it was 11 per cent, with travellers' diarrhoea and without an antibiotic 21 per cent, with both 37 per cent. In South Asia the values were 23, 47 and 80 per cent.

For you this means: anyone who reaches for an antibiotic because of mild travellers' diarrhoea is very likely to bring something home from a high risk region that they will not get rid of again. The authors therefore advise against it explicitly.

Kantele A, Lääveri T, Mero S et al. Antimicrobials increase travelers' risk of colonization by extended-spectrum betalactamase-producing Enterobacteriaceae. Clin Infect Dis. 2015;60(6):837-846. PMID: 25613287 · DOI: 10.1093/cid/ciu957 [Cohort, n=430]

What belongs in the travel kit

Sachets of rehydration salt. Light, cheap, in case of doubt the most important thing in the luggage. In many destination countries they are available locally too.
A thermometer. Because fever marks the line at which you stop treating yourself.
An anti-diarrhoeal with its limits clearly in mind. Not with fever, not with blood in the stool, not over several days, not in children.
Soap and disinfectant wipes for situations without running water, with an awareness of their limits against norovirus.
Emergency number and insurance details to hand, plus the address of a medical contact point at your destination.
An antibiotic only after travel medicine advice, if at all, and then as an emergency reserve for a severe course. Not as daily prevention.

A change of perspective

Most travellers ask: how do I prevent it completely?

The more useful question is: how do I get through well if it happens anyway? A sachet of rehydration salt in the suitcase changes the course more reliably than any ordering strategy in a restaurant.

And now you know why the most exciting line in the travel kit is the one with the electrolyte powder.

What can linger afterwards: four routes that need to be kept apart

The infection is over. The diarrhoea too. And still something is not right.

The belly is flat in the morning and bloated in the evening. Certain foods suddenly do not work any more. Bowel habit has become unpredictable. And when you say so, you often hear: that is probably psychological.

That is the point where I ask the most questions. Not because the mind plays no role, it plays a large one, and in the figures further down it even sits very high. But because alongside that there are well described physical routes for this pattern that should be kept apart. Mind and body are not alternatives here to be played off against each other. What I reject is only the short circuit of using the word psychological to end the physical work-up.

First the frame: the vast majority of people are back where they were after one to two weeks. If not, there are four routes that are well described in the literature.

Route one: post-infectious irritable bowel syndrome

Meta-analysis, 45 cohorts, n=21,421 About one in ten

A team around Fabiane Klem at the Mayo Clinic pooled 45 cohort studies with 21,421 people after infectious enteritis, with follow-up from three months to ten years.

After twelve months a pooled 10.1 per cent had irritable bowel syndrome, after more than twelve months 14.5 per cent. The risk was 4.2-fold higher in the first year and still 2.3-fold afterwards. It was higher in women (odds ratio 2.2), with antibiotics given during the illness (1.7) and with a severe acute course. And, in fairness this belongs here too, also with psychological features: anxiety 2.0, depression 1.5, somatisation 4.1 and neuroticism 3.3. The authors also point to considerable differences between the studies. After protozoa or parasites, as many as 41.9 per cent developed irritable bowel syndrome, after bacterial infections 13.8 per cent.

For you this means: if your gut has been different since an infection, you are neither imagining it nor rare. You are about one in ten.

Klem F, Wadhwa A, Prokop LJ et al. Prevalence, Risk Factors, and Outcomes of Irritable Bowel Syndrome After Infectious Enteritis: A Systematic Review and Meta-analysis. Gastroenterology. 2017;152(5):1042-1054.e1. PMID: 28069350 · DOI: 10.1053/j.gastro.2016.12.039 [Meta-analysis, k=45, n=21421]

The most honest answer to the question of duration comes from a small Canadian town. In May 2000, after heavy rainfall, bacteria got into the drinking water supply in Walkerton, Ontario. Thousands fell ill, and the consequences were followed systematically over years.

Prospective cohort, n=1,166 Walkerton, eight years later

A team around John Marshall examined those affected by the outbreak again after eight years, with 1,166 people entering the analysis.

Among the 742 people with acute gastroenteritis during the outbreak, the frequency of irritable bowel syndrome fell from 28.3 per cent after two to three years to 15.4 per cent after eight years. Compared with those not affected it remained clearly elevated (odds ratio 3.12, confidence interval 1.99 to 5.04). Risk factors after eight years were female sex, younger age, pre-existing anxiety or depression as well as fever or weight loss during the acute illness.

For you this means: it gets better for most people, but slowly, over years rather than weeks. And in some, something remains. Knowing that is less comforting than reassurance and still more helpful.

Marshall JK, Thabane M, Garg AX, Clark WF, Moayyedi P, Collins SM. Eight year prognosis of postinfectious irritable bowel syndrome following waterborne bacterial dysentery. Gut. 2010;59(5):605-611. PMID: 20427395 · DOI: 10.1136/gut.2009.202234 [Cohort, n=1166]

Among the children of the same cohort the cumulative frequency was 10.5 per cent compared with 2.5 per cent in the controls. So it is not purely an adult phenomenon. After travellers' diarrhoea specifically, a meta-analysis from Tübingen found a relative risk of 3.35 and an overall incidence of 5.4 versus 1.4 per cent.

Whether the pathogen plays a role was examined by a Danish meta-analysis of 34 papers: after campylobacter 12 per cent, after salmonellosis 12 per cent, after shigellosis 11 per cent. On viruses and parasites, by contrast, there are hardly any studies. So of all things, the most common pathogen in Germany, norovirus, has the thinnest evidence. I do not extrapolate that.

In 2019 the Rome Foundation recognised post-infectious irritable bowel syndrome as an entity of its own and explicitly noted that there is no proven specific drug strategy for it. More on this, meaning mechanism, diagnostics and what is actually available, is in the separate article Irritable bowel: finding causes. Here I stop at the threshold.

Route two: a temporary lactase deficiency

The enzyme lactase sits on the tips of the intestinal villi, exactly where an infection does damage first. It takes weeks until this outermost layer is rebuilt, and during that time lactose can cause symptoms that were never there before.

That is usually temporary and no reason to drop dairy permanently. How to tell it apart from a real intolerance is in Lactose, fructose, sorbitol.

Route three: bile acid diarrhoea

In some people with persistently watery diarrhoea after an infection, the cause no longer lies with the pathogen but with the bile acids, which are no longer properly reclaimed and work like a laxative in the large intestine.

A meta-analysis of 36 studies with 5,028 people with functional diarrhoea found an abnormal SeHCAT test in 30.8 per cent and abnormal values in other procedures in around a quarter. That is relevant because this route opens up a treatment direction of its own, different from the one in irritable bowel syndrome. How much that brings in the individual case varies, and the paper cited says nothing about it itself, it only counted how often the tests are abnormal. In Germany the SeHCAT test is also hard to access. Details in Bile, bile acids and TUDCA and in Chronic diarrhoea: the overlooked causes.

Route four: disturbed small bowel motility

The fourth route is the most speculative and at the same time the most elegant mechanistically. Some bacterial pathogens produce a toxin called cytolethal distending toxin B. The body forms antibodies against it. And these antibodies apparently resemble a body's own protein called vinculin so closely that they can hit it too. Vinculin sits, among other places, in the cells that set the rhythm of bowel movement.

Biomarker validation, n=2,681 Elegant, but weak as a test

A team around Mark Pimentel measured antibodies against CdtB and against vinculin in 2,375 people with diarrhoea-predominant irritable bowel syndrome, 142 with inflammatory bowel disease, 121 with coeliac disease and 43 healthy people.

Both titres were significantly higher in diarrhoea-predominant irritable bowel syndrome. At an optimised cut-off, anti-CdtB reached a specificity of 91.6 per cent, but a sensitivity of only 43.7 per cent. A negative test therefore rules out next to nothing.

For you this means: this is a well reasoned hypothesis with a weak test, not an established diagnostic procedure. The sponsor of the study was a pharmaceutical company, two authors were employed there. That belongs said.

Pimentel M, Morales W, Rezaie A et al. Development and validation of a biomarker for diarrhea-predominant irritable bowel syndrome in human subjects. PLoS One. 2015;10(5):e0126438. PMID: 25970536 · DOI: 10.1371/journal.pone.0126438 [Cohort, n=2681]

What follows from this in practice, meaning when a breath test makes sense and what it can do, is in SIBO in the small intestine and in Why SIBO comes back.

And how long does the microbiome need?

I hear this question almost every time. The honest answer is: there is no good study on it after gastroenteritis. The best available number comes from a different model.

Intervention study, n=12 About six weeks, but not completely

An international team around Albert Palleja gave twelve healthy men a combination of three antibiotics for four days and followed the microbiome afterwards for six months with shotgun metagenomics.

At first enterobacteria and other problem organisms flourished, bifidobacteria and butyrate producers declined. After about 1.5 months the composition approached the baseline again. Nine species that had previously been present in all twelve participants could no longer be detected in most of them after 180 days.

For you this means: the rough rebuild goes faster than feared, but the complete return does not necessarily. Important for context: this is an antibiotic model with twelve healthy men, not a gastroenteritis model.

Palleja A, Mikkelsen KH, Forslund SK et al. Recovery of gut microbiota of healthy adults following antibiotic exposure. Nat Microbiol. 2018;3(11):1255-1265. PMID: 30349083 · DOI: 10.1038/s41564-018-0257-9 [Cohort, n=12]

If antibiotics were involved in your case, you will find the topic explored in depth in The gut after antibiotics.

A change of perspective

Many people read these weeks as a sign that something has broken.

What you feel is usually a system in the recovery phase and not a system in defect. The gut lining renews itself every few days, the enzymes come back, the bacterial community sorts itself out anew. That takes longer than a sick note lasts, and that is normal.

Even so, this remains important: blood in the stool, weight loss, fever or night-time symptoms always need to be investigated and not read as a recovery phase.

And now you know why the question about the aftermath is not a side issue.

The coming weeks: a way of thinking instead of a protocol

So what do you actually do in the weeks after an infection?

I have to be honest here: there are no controlled studies on it. No team has ever investigated in a randomised way how best to rebuild the gut after gastroenteritis. Everything I can say about it is either extrapolation from other fields or clinical observation. That is exactly how I label it.

What I observe clinically

Three patterns I meet again and again in the consulting room

First: fibre comes back too fast. After a week of rusk, many people jump straight to wholegrain, pulses and raw vegetables. But the bacterial community that normally processes these fibres is still thinly staffed. The result is bloating, and that is then read as a new intolerance. Increasing slowly over weeks is the way I have better experience with in the consulting room. That is an observation and not proof of effect. What fibre achieves and what it does not is in Fibre: what remains of the myths.

Second: restriction comes too early. Anyone with symptoms after an infection often lands within days on a strict FODMAP diet. I consider that a very early step. A restriction that begins too early and stays too long impoverishes the diet and the bacterial community alike. FODMAP is a good tool in the right place, with a reintroduction phase and a time limit. What that looks like is in Using FODMAP properly.

Third: the autonomic side is overlooked. After a sleepless night on the bathroom floor the body is not only poorer in fluid. Sleep is disturbed, the muscles are tired, food intake was minimal for days. I observe in my consulting room that many people find it easier when sleep, daylight and gentle movement get room again early and not only at the end. That is an observation and not proof of effect. There are no controlled studies on it, and whether it goes faster for you is not something I can derive from it.

What interests me in this phase is not a preparation but an order. First fluid and salt. Then normal food with enough protein. Then slowly more plant variety. What actually feeds the microbiome is in Prebiotics: what really feeds the microbiome.

One trap before you leave something out

After an infection that does not quite pass, many people cut out grains first. The impulse is understandable, and in some it does improve something. But there is an order here that you can only get wrong once.

If coeliac disease is a possibility, meaning the immune-mediated reaction to gluten, then the diagnostics belong before the avoidance and not after. On a gluten-free diet the antibodies in the blood fall and the changes in the small bowel lining recede. A test done only afterwards can come back unremarkable although coeliac disease is present. The diagnosis can then no longer be made reliably for the time being, and the way back leads through a renewed gluten challenge over weeks, which nobody likes to take on.

In practice this means: investigate first, then leave out, not the other way round. The same applies to other diagnostics that are on the table. How the work-up runs and what the individual values mean is in Recognising coeliac disease.

When patience turns into a work-up

These limits I would not cross

Diarrhoea for more than four weeks. From here the diarrhoea counts as chronic and is no longer attributed to the infection before someone has looked.
Blood in the stool at any point, even if it happened only once.
Unintended weight loss beyond the first days.
Fever that returns or does not fully go away.
Night-time symptoms that pull you out of sleep.
Anaemia or abnormal inflammatory markers in the laboratory.
A new persistent change in bowel habit from around 45 to 50 years of age.

In these cases the right order is: investigate first, then optimise. A stool test on the composition of the gut flora does not replace basic diagnostics at this point, it comes afterwards. What such a test can and cannot do is in Stool testing and PCR diagnostics. And if a colonoscopy or another examination has been recommended, it is not postponed in favour of dietary measures.

Three things you can do today

Concrete and without effort

Put rehydration salt in your cupboard, now, while you are well. The worst time for a trip to the pharmacy is the night you need it. The same goes for the suitcase before the next long-haul trip. One restriction on this: rehydration solutions contain potassium. If your kidney function is reduced or you take ACE inhibitors, sartans or potassium-sparing diuretics, please clarify medically which amount fits for you before you drink such sachets on a large scale.
Remember the two words where the line runs most clearly: fever and blood. As soon as one of them is there, the situation belongs to be assessed medically and not self-treated. But two words are not the whole check. Loperamide also does not fit when the diarrhoea began during or after a course of antibiotics, when a bowel obstruction is suspected, with inflammatory bowel disease in a flare, in children, and in pregnancy and breastfeeding without medical advice. The medicine is pharmacy-only. Read the package leaflet and ask at the pharmacy before you take it.
If your gut has been different since an infection, write it down and take it with you. When was the infection, where were you, were there antibiotics, what has changed since. These four details change a conversation more than you might think, because otherwise nobody notices the connection.

In closing

A tide going out looks like a loss. The ground lies dry, everything looks barer than before. But the tide comes back, and it almost always does, even if it takes longer than you hope. Your task in the first days is small and unspectacular: to make sure enough comes back in. And in the weeks that follow: not to forget that there was a beginning.

Frequently asked questions about stomach and bowel infections

How long does a stomach and bowel infection usually last?

In most cases the worst hours are over after one to two days. The German S2k guideline gives an incubation period of 6 to 72 hours for salmonella, usually 12 to 36 hours, and a diarrhoea that stops within 4 to 10 days. For campylobacter the incubation period is usually 2 to 5 days. A norovirus infection is typically fierce and short. If the diarrhoea lasts longer than a week, it needs to be looked at medically.

What should I eat in the first days when everything comes back up?

In the first hours it is not about food but about fluid in small, frequent sips. As soon as food is imaginable again, there is no argument for going hungry. A Cochrane analysis of twelve studies with 1,283 children found no increased risk of unscheduled infusions, of vomiting or of persistent diarrhoea with early refeeding. Salty broth, boiled potato, rice and banana are good first steps because they provide sodium, some starch and little fat.

What do I eat afterwards, when the diarrhoea stops but my stomach still feels odd?

In this phase the lining is still rebuilding its digestive enzymes. Lactose and larger amounts of fat are therefore often harder to handle for a few weeks than usual. A slow rebuild makes sense: first cooked vegetables, egg, rice and potato, then step by step more fibre, then raw vegetables and pulses again. Anyone who eats everything too soon easily mistakes the transition phase for a new intolerance.

Is water enough, or do I really need an electrolyte solution?

In a mild course, whatever you drink anyway is usually enough. With heavy, watery diarrhoea plain water is not enough, because what is mainly lost with the stool is sodium. The gut cell takes up sodium through a coupled transporter that carries glucose along at the same time. Only when both are in the gut together does water follow passively. That is why rehydration solutions contain salt and sugar in a fixed ratio.

Can I mix an electrolyte solution myself, and what is the difference to the pharmacy version?

I advise against mixing it yourself, for a very practical reason. The gap between too little and too much salt is narrower than a household scale can show, and too much salt can become dangerous for children and older people. Ready-made sachets from the pharmacy hit the composition more precisely, contain citrate as a buffer, cost little and are clearly the preferred choice for children. Children have their own rules on this question anyway and belong in medical hands. One restriction for adults: rehydration solutions contain potassium. With reduced kidney function or under ACE inhibitors, sartans and potassium-sparing diuretics, the right amount needs to be clarified medically first.

Are cola and pretzel sticks good or bad for diarrhoea?

The German S2k guideline is pleasantly calm here. It states that pure fruit juices, tap water and lemonade are unsuitable for rehydration, but says in the same breath that in mild cases diluted juices with pretzel sticks or chicken broth can be sufficient. Cola as the only drink is too high in sugar, because the high sugar load pulls water into the gut osmotically. As a combination of diluted fluid and salt from outside, the old household rule is not wrong, it just does not carry a severe course.

What helps against diarrhoea with norovirus, and when is it better not to take loperamide?

There is no agent against the virus itself, here only fluid counts. According to the German guideline, loperamide can be used in adults without fever and without blood in the stool for under 48 hours. That is also exactly where the limit lies: with fever, with bloody diarrhoea or when an invasive pathogen is suspected, it does not fit. In children the guideline says loperamide should not be used. In a retrospective cohort of 278 children after an EHEC outbreak, giving motility inhibitors in the first three days was associated with an almost threefold risk of haemolytic uraemic syndrome. Fever and blood are not the only limits, though. Loperamide also does not fit when the diarrhoea began during or after a course of antibiotics, when a bowel obstruction is suspected, with inflammatory bowel disease in a flare, and in pregnancy and breastfeeding without medical advice. The medicine is pharmacy-only. Read the package leaflet and ask at the pharmacy before you take it.

Do I need an antibiotic if bacteria were found in my stool?

In healthy adults with an uncomplicated course, usually not. A meta-analysis of eleven randomised studies found symptoms shortened by an average of 1.32 days for campylobacter. For non-typhoidal salmonella a Cochrane review with twelve studies found no benefit at all, but an almost doubled probability of still shedding the same serovar after a month. There are still clear situations in which an antibiotic is right, for example in a severe course, with immunosuppression or with certain pathogens. That decision belongs in medical hands, and a therapy that has already been started is not stopped on your own.

How long am I contagious, and when may I go back to work or nursery?

Shedding and risk of transmission are two different things. Norovirus is usually still shed for 7 to 14 days after the acute illness, campylobacter for an average of 2 to 5 weeks, salmonella in adults for an average of one month. Nevertheless the expert opinion of the German guideline is: 48 hours after vomiting and diarrhoea have ended, the risk of transmission with careful hand hygiene has dropped far enough that a return is possible. Food handling occupations and communal institutions follow their own rules under the German Infection Protection Act.

Is hand sanitiser enough against norovirus?

Not as a substitute for washing. In a fingerpad model with real Norwalk virus, an alcohol-based hand gel reduced the virus signal by only 0.14 to 0.34 log steps. Antibacterial liquid soap reached 0.67 to 1.20 log steps, plain water rinsing 0.58 to 1.58. The practical conclusion is unspectacular: water and soap, long and thorough, plus a surface agent with documented virucidal activity for door handles, the flush button and taps.

When do I need to see a doctor with a stomach and bowel infection?

With blood in the stool, with black tarry stool, with high fever, with severe or one-sided abdominal pain, with vomiting and no fluid intake at all over hours, with clearly less urine, with drowsiness or confusion, with diarrhoea lasting more than a week and with symptoms after a trip to the tropics. The same applies to unintended weight loss, to night-time symptoms that wake you, to a new persistent change in bowel habit from around 45 to 50 years of age, to anaemia and to bowel cancer or inflammatory bowel disease in the family. Anyone who is older, has pre-existing conditions or takes fluid-reducing medication should ask earlier than the rest. Outside surgery hours the German out-of-hours medical service can be reached on 116117. With confusion, circulatory weakness, clouded consciousness, chest pain or breathlessness this is an emergency: call 112.

How do I prevent travellers' diarrhoea, and do probiotics help with that?

The sobering part first: in a critical review, seven of eight studies found no link between food choice and the risk of falling ill. The rules are not wrong, they only work where you control the kitchen yourself. With probiotics the question splits: in acute treatment the Cochrane review with 82 studies and 12,127 participants found no difference. The carrying figure comes from the two studies with a low risk of bias and 1,770 participants between them, and Cochrane words it carefully: probiotics probably make little or no difference. In travel prevention it looks different. A strain-separated meta-analysis found a signal for Saccharomyces boulardii CNCM I-745, the risk of falling ill could be lower with it (relative risk 0.79), while other strains showed no robust effect. Important alongside this: in Germany this yeast is a licensed medicine and not suitable for everyone. With a weakened immune system and with an indwelling central venous catheter it should not be taken, because fungal bloodstream infections have been described in such situations. That needs to be clarified medically or at the pharmacy beforehand.

What belongs in the travel kit, and should I take an antibiotic as prevention?

Sensible items are sachets of rehydration salt, a thermometer, an anti-diarrhoeal with its limits clearly in mind, soap or disinfectant wipes and an emergency number. On preventive antibiotic use the German S2k guideline says no, with a strong recommendation. The reasons are resistance, side effects up to a severe inflammation of the bowel, and a false sense of security. A Finnish cohort found ESBL colonisation of up to 80 per cent in travellers with diarrhoea plus an antibiotic in South Asia. The substances discussed for this are prescription-only and in Germany partly not licensed for this purpose at all. Fluoroquinolones have not been licensed for the prevention of travellers' diarrhoea since a 2019 decision by the German regulator BfArM, because of severe and in part lasting side effects affecting tendons, nerves and blood vessels. This question therefore belongs in a travel medicine consultation and not in a guide article.

My stomach has not been normal since an infection months ago. What can that be?

You are neither imagining it nor alone with it. A meta-analysis of 45 cohort studies with 21,421 people found irritable bowel syndrome within twelve months in a pooled 10.1 per cent after infectious enteritis, with a 4.2-fold increased risk. Alongside that there are three further routes that need to be kept apart: a temporary lactase deficiency, bile acid diarrhoea and disturbed small bowel motility with bacterial overgrowth. Which of these applies is not decided by feeling but by the course and by diagnostics. Blood, weight loss, fever or night-time symptoms always need to be investigated first.

Where this topic connects to the rest of the gut

A stomach and bowel infection is an event with a history and with an aftermath. The following articles pick up exactly the questions that most often stay open after an infection.

Gut reset: the overall concept

How the individual building blocks of gut restoration belong together

Irritable bowel: finding causes

The place where post-infectious irritable bowel syndrome is covered in detail

Chronic diarrhoea

When the diarrhoea is still there after four weeks, a different search begins

The gut after antibiotics

What the rebuild needs when a therapy was necessary

Prebiotics and resistant starch

What the bacterial community rebuilds itself with after a disturbance

Fibre: the myths

Why the number 30 says less than it promises

Shukri Jarmoukli

Physician · Area of focus: integrative medicine · ViveCura Berlin

Shukri Jarmoukli, physician in Berlin. I write these articles as general health information and not as advertising for a particular treatment. With gut topics I am less interested in which preparation is currently being advertised than in which question is actually still open before the next step.

With acute gastroenteritis I am deliberately sparing. The evidence on probiotics in the acute case is clear, and I consider the position of the professional society well reasoned here. What occupies me instead is the time afterwards, because that is where the questions are asked that nobody else asks.

This text does not replace medical advice, an examination or a diagnosis, and no offer to treat a particular illness follows from it. It is meant to help you have the right order in mind if it happens and to ask better questions at your next appointment. For acute symptoms your own general practice is the right address, outside surgery hours the German out-of-hours medical service on 116117, in an emergency 112.

ViveCura, Privatpraxis Shukri Jarmoukli, Skalitzer Straße 137, 10999 Berlin

Scientific sources

Manthey CF, Epple HJ, Keller KM et al. S2k guideline on gastrointestinal infections of the German Society for Gastroenterology, Digestive and Metabolic Diseases (DGVS). Version 2.1, November 2023. AWMF register number 021-024. AWMF register [Guideline]
Riddle MS, DuPont HL, Connor BA. ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults. Am J Gastroenterol. 2016;111(5):602-622. PMID: 27068718 · DOI: 10.1038/ajg.2016.126 [Guideline]
Riddle MS, Connor BA, Beeching NJ et al. Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report. J Travel Med. 2017;24(suppl_1):S57-S74. PMID: 28521004 · DOI: 10.1093/jtm/tax026 [Guideline]
Guarino A, Ashkenazi S, Gendrel D, Lo Vecchio A, Shamir R, Szajewska H. ESPGHAN/ESPID evidence-based guidelines for the management of acute gastroenteritis in children in Europe: update 2014. J Pediatr Gastroenterol Nutr. 2014;59(1):132-152. PMID: 24739189 · DOI: 10.1097/MPG.0000000000000375 [Guideline]
Barbara G, Grover M, Bercik P et al. Rome Foundation Working Team Report on Post-Infection Irritable Bowel Syndrome. Gastroenterology. 2019;156(1):46-58.e7. PMID: 30009817 · DOI: 10.1053/j.gastro.2018.07.011 [Guideline]
Hahn S, Kim Y, Garner P. Reduced osmolarity oral rehydration solution for treating dehydration due to diarrhoea in children: systematic review. BMJ. 2001;323(7304):81-85. PMID: 11451782 · DOI: 10.1136/bmj.323.7304.81 [Meta-analysis, k=15, n=2397]
Hahn S, Kim S, Garner P. Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children. Cochrane Database Syst Rev. 2002;(1):CD002847. PMID: 11869639 · DOI: 10.1002/14651858.CD002847 [Systematic Review]
Gregorio GV, Gonzales ML, Dans LF, Martinez EG. Polymer-based oral rehydration solution for treating acute watery diarrhoea. Cochrane Database Syst Rev. 2016;12(12):CD006519. PMID: 27959472 · DOI: 10.1002/14651858.CD006519.pub3 [Systematic Review]
Gregorio GV, Dans LF, Silvestre MA. Early versus delayed refeeding for children with acute diarrhoea. Cochrane Database Syst Rev. 2011;2011(7):CD007296. PMID: 21735409 · DOI: 10.1002/14651858.CD007296.pub2 [Meta-analysis, k=12, n=1283]
MacGillivray S, Fahey T, McGuire W. Lactose avoidance for young children with acute diarrhoea. Cochrane Database Syst Rev. 2013;2013(10):CD005433. PMID: 24173771 · DOI: 10.1002/14651858.CD005433.pub2 [Meta-analysis, k=33, n=2973]
Bell BP, Griffin PM, Lozano P, Christie DL, Kobayashi JM, Tarr PI. Predictors of hemolytic uremic syndrome in children during a large outbreak of Escherichia coli O157:H7 infections. Pediatrics. 1997;100(1):E12. PMID: 9200386 · DOI: 10.1542/peds.100.1.e12 [Cohort, n=278]
Ternhag A, Asikainen T, Giesecke J, Ekdahl K. A meta-analysis on the effects of antibiotic treatment on duration of symptoms caused by infection with Campylobacter species. Clin Infect Dis. 2007;44(5):696-700. PMID: 17278062 · DOI: 10.1086/509924 [Meta-analysis, k=11]
Onwuezobe IA, Oshun PO, Odigwe CC. Antimicrobials for treating symptomatic non-typhoidal Salmonella infection. Cochrane Database Syst Rev. 2012;11(11):CD001167. PMID: 23152205 · DOI: 10.1002/14651858.CD001167.pub2 [Meta-analysis, k=12, n=767]
Collinson S, Deans A, Padua-Zamora A et al. Probiotics for treating acute infectious diarrhoea. Cochrane Database Syst Rev. 2020;12(12):CD003048. PMID: 33295643 · DOI: 10.1002/14651858.CD003048.pub4 [Meta-analysis, k=82, n=12127]
Schnadower D, Tarr PI, Casper TC et al. Lactobacillus rhamnosus GG versus Placebo for Acute Gastroenteritis in Children. N Engl J Med. 2018;379(21):2002-2014. PMID: 30462938 · DOI: 10.1056/NEJMoa1802598 [RCT, n=971]
Shlim DR. Looking for evidence that personal hygiene precautions prevent traveler's diarrhea. Clin Infect Dis. 2005;41 Suppl 8:S531-S535. PMID: 16267714 · DOI: 10.1086/432947 [Review article]
McFarland LV. Meta-analysis of probiotics for the prevention of traveler's diarrhea. Travel Med Infect Dis. 2007;5(2):97-105. PMID: 17298915 · DOI: 10.1016/j.tmaid.2005.10.003 [Meta-analysis, k=12]
McFarland LV, Goh S. Are probiotics and prebiotics effective in the prevention of travellers' diarrhea: A systematic review and meta-analysis. Travel Med Infect Dis. 2019;27:11-19. PMID: 30278238 · DOI: 10.1016/j.tmaid.2018.09.007 [Systematic Review]
DuPont HL, Ericsson CD, Johnson PC, Bitsura JA, DuPont MW, de la Cabada FJ. Prevention of travelers' diarrhea by the tablet formulation of bismuth subsalicylate. JAMA. 1987;257(10):1347-1350. PMID: 3820443 (no DOI assigned) [RCT, n=182]
DuPont HL, Jiang ZD, Okhuysen PC et al. A randomized, double-blind, placebo-controlled trial of rifaximin to prevent travelers' diarrhea. Ann Intern Med. 2005;142(10):805-812. PMID: 15897530 · DOI: 10.7326/0003-4819-142-10-200505170-00005 [RCT, n=210]
Alajbegovic S, Sanders JW, Atherly DE, Riddle MS. Effectiveness of rifaximin and fluoroquinolones in preventing travelers' diarrhea (TD): a systematic review and meta-analysis. Syst Rev. 2012;1:39. PMID: 22929178 · DOI: 10.1186/2046-4053-1-39 [Systematic Review]
Kantele A, Lääveri T, Mero S et al. Antimicrobials increase travelers' risk of colonization by extended-spectrum betalactamase-producing Enterobacteriaceae. Clin Infect Dis. 2015;60(6):837-846. PMID: 25613287 · DOI: 10.1093/cid/ciu957 [Cohort, n=430]
Milbrath MO, Spicknall IH, Zelner JL, Moe CL, Eisenberg JNS. Heterogeneity in norovirus shedding duration affects community risk. Epidemiol Infect. 2013;141(8):1572-1584. PMID: 23507473 · DOI: 10.1017/S0950268813000496 [Systematic Review]
Liu P, Yuen Y, Hsiao HM, Jaykus LA, Moe C. Effectiveness of liquid soap and hand sanitizer against Norwalk virus on contaminated hands. Appl Environ Microbiol. 2010;76(2):394-399. PMID: 19933337 · DOI: 10.1128/AEM.01729-09 [In vitro]
Klem F, Wadhwa A, Prokop LJ et al. Prevalence, Risk Factors, and Outcomes of Irritable Bowel Syndrome After Infectious Enteritis: A Systematic Review and Meta-analysis. Gastroenterology. 2017;152(5):1042-1054.e1. PMID: 28069350 · DOI: 10.1053/j.gastro.2016.12.039 [Meta-analysis, k=45, n=21421]
Marshall JK, Thabane M, Garg AX, Clark WF, Moayyedi P, Collins SM. Eight year prognosis of postinfectious irritable bowel syndrome following waterborne bacterial dysentery. Gut. 2010;59(5):605-611. PMID: 20427395 · DOI: 10.1136/gut.2009.202234 [Cohort, n=1166]
Thabane M, Simunovic M, Akhtar-Danesh N et al. An outbreak of acute bacterial gastroenteritis is associated with an increased incidence of irritable bowel syndrome in children. Am J Gastroenterol. 2010;105(4):933-939. PMID: 20179687 · DOI: 10.1038/ajg.2010.74 [Cohort]
Svendsen AT, Bytzer P, Engsbro AL. Systematic review with meta-analyses: does the pathogen matter in post-infectious irritable bowel syndrome? Scand J Gastroenterol. 2019;54(5):546-562. PMID: 31112663 · DOI: 10.1080/00365521.2019.1607897 [Systematic Review]
Schwille-Kiuntke J, Mazurak N, Enck P. Systematic review with meta-analysis: post-infectious irritable bowel syndrome after travellers' diarrhoea. Aliment Pharmacol Ther. 2015;41(11):1029-1037. PMID: 25871571 · DOI: 10.1111/apt.13199 [Systematic Review]
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Transparency on the evidence: where the data are thin

Almost all rehydration data come from paediatrics. The German guideline itself states that oral rehydration solution has been studied almost exclusively in paediatrics, and at the same time states that the results are transferable to adults without restriction. That transfer is professionally backed; it is not a study result in adults. That applies equally to all the Cochrane work cited here on rehydration solution, on early refeeding and on lactose.
Temporary lactase deficiency in adults is mechanistically well explainable and clinically known. The figure of around 18 hours of shorter diarrhoea comes from small children in clinics, though. For adults there is no comparable body of data.
Data on post-infectious irritable bowel syndrome after norovirus are missing. The Danish meta-analysis states explicitly that there are hardly any studies on viral and parasitic pathogens. Of all things, the most common pathogen in Germany is thus the one with the thinnest follow-up data. I therefore do not scale the bacterial figures up to norovirus.
The CdtB vinculin hypothesis is a hypothesis. The biomarker has a sensitivity of only 43.7 per cent, so a negative test says almost nothing. The key study was sponsored by a pharmaceutical company, two authors were employed there. It stands here as a mechanistic explanation, not as a diagnostic recommendation.
The figure on microbiome recovery comes from an antibiotic model with twelve healthy men, not from a follow-up study after gastroenteritis. Such a study does not exist. The roughly 1.5 months are therefore an orientation and not a prognosis.
Polymer-based rehydration solutions are rated by Cochrane throughout as low to very low quality of evidence with substantial heterogeneity. They stand here as a note, not as a recommendation.
There is a contradicting paper on loperamide and HUS. A smaller Japanese investigation after a different outbreak found no association. I rely on the larger and methodologically better cohort, because this is a safety statement. I make this judgement transparent instead of leaving the contradiction out.
Racecadotril is named by the German guideline as an alternative, but plays hardly any role in German everyday practice in adults. Comparative data against loperamide exist but are not extensive. The substance is prescription-only or pharmacy-only depending on the preparation, and rare but serious hypersensitivity reactions have been described.
This text is written by me and checked by me. An independent professional second reading by another person has not taken place. The source entries carry a PMID, a DOI or a register number so that you can look up every figure yourself.
There are no controlled studies on the weeks after the infection. No randomised investigation exists on a structured rebuild after gastroenteritis. Everything in the last section is either extrapolation from other fields or clinical observation, and I have labelled it as such.
What deliberately does not stand here. No personal dosing recommendation, no treatment protocol and no instructions for mixing up a rehydration solution. The WHO composition is described as a composition and not as a kitchen recipe, ready-made preparations from the pharmacy are more precise and the preferred choice for children. Where prescription-only substances or substances not available in Germany come up, I name them with their prescription status, their licensing situation and their risks, but without efficacy percentages and without dosing. On infants and small children nothing stands here on purpose, apart from the note that their own rules apply and that the assessment belongs in medical hands. From no sentence in this article does it follow that a prescribed medication should be changed, reduced or stopped on your own, that a started antibiotic therapy should be broken off, or that a recommended colonoscopy, endoscopy or laboratory work-up should be postponed or replaced. Every adjustment belongs under medical supervision.

Stomach and bowel infection: what counts in the first days and what can linger afterwards

All articles from the gut cluster

What is waiting for you here

What is happening inside you right now, and who can be behind it

Why your body throws out the water it needs

When a stool sample makes sense and when it does not

Fluid: the one thing that counts in the first 48 hours

Why water alone is not enough with heavy diarrhoea

The WHO composition, in numbers

Almost all these numbers come from paediatrics

Cola and pretzel sticks: the argument nobody needs

Mixing it yourself or buying it ready-made

Seven groups in which the threshold lies lower

What you can give and what you had better leave alone

Loperamide: the limit is sharp, and it has a reason

Loperamide: the situations in which it does not fit

Bismuth, or: why international guides run into a void here

Antibiotics: the numbers instead of the claim

Probiotics in the acute phase: here the guideline has good reasons

Building food back up: the BRAT diet examined critically

Milk and lactose in the first days

How I would describe getting back to eating

As long as nothing stays down: fluid only, in small sips

As soon as hunger comes: starchy, salty, low in fat

After one to two days: add protein

Then step by step back to normal food

Transmission: how long, how within the household, when back to work and nursery

Shedding is not the same as risk of transmission

The 48 hour rule

Hand washing versus hand disinfection

What can practically help in the household

Travellers' diarrhoea: what prevents, what does not, what to pack

The uncomfortable finding on the hygiene rules

Anyone who dampens stomach acid lowers a barrier

Probiotics for prevention: here it looks different from the acute case

Antibiotics for prevention: effectiveness is not the point of dispute

Why effectiveness alone is not enough

What belongs in the travel kit

What can linger afterwards: four routes that need to be kept apart

Route one: post-infectious irritable bowel syndrome

Route two: a temporary lactase deficiency

Route three: bile acid diarrhoea

Route four: disturbed small bowel motility

And how long does the microbiome need?

The coming weeks: a way of thinking instead of a protocol

Three patterns I meet again and again in the consulting room

One trap before you leave something out

When patience turns into a work-up

Three things you can do today

Concrete and without effort

Frequently asked questions about stomach and bowel infections

Where this topic connects to the rest of the gut

Gut reset: the overall concept

Irritable bowel: finding causes

Chronic diarrhoea

The gut after antibiotics

Prebiotics and resistant starch

Fibre: the myths

Shukri Jarmoukli

Scientific sources

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