Irritable stomach: when the upper abdomen will not settle and the examination finds nothing

You are sitting at the table, third bite, and the plate is suddenly too full. Not in your head. In your belly.

There is pressure under the rib cage, as if someone had inflated a balloon from the inside. You put the fork down. Two hours later it is still there.

And then came the gastroscopy. On waking up, the sentence you had waited three weeks for: everything normal.

Many people know exactly this moment and the emptiness that follows. Relief and disappointment in the same breath. Nothing found means, for you: I still have the symptoms, and now I have no explanation either.

I would like to turn that sentence around. A normal result is a result: no ulcer, no tumour, no open inflammation. It simply does not answer the second question. And that question is: what is going on then? There is considerably more of an answer to that today than there was fifteen years ago.

What functional dyspepsia is, and why the diagnosis feels like a non finding

Picture two slips of paper. On one there is a name for what you have. On the other there is what you do not have.

With functional dyspepsia you usually get the second slip. No ulcer, no inflammation, no tumour. That sounds like nothing, and that is exactly the thinking error that accompanies many people for years.

Because functional dyspepsia, in everyday German called irritable stomach, is a positively defined diagnosis. It has criteria, four cardinal symptoms, two subgroups. And since 2025 a German language guideline of its own.

The word functional carries a burden here that it does not deserve. In everyday speech it sounds like imagined. Something quite different is meant: the disturbance sits in the control system, not in the structure.

An image for it: a piano can be out of tune without a piece of wood being broken. From the outside you see nothing. You can hear it immediately.

How common this is

You are not rare with this, you are very ordinary.

The 20.8 percent come from a meta-analysis of 100 study populations with 312,415 people. More often affected: women, smokers, people with Helicobacter pylori and people who regularly take painkillers of the NSAID type, with an odds ratio of 1.59. That last number is the only one that can be changed. And even so: long term medication is never stopped single handedly.

Since April 2025 there has been a German language guideline on functional dyspepsia for the first time. The S1 guideline of the German Society for Neurogastroenterology and Motility classifies it as a disorder of gut brain interaction and works with a prevalence in the order of 10 percent. It places psychoeducation, dietary counselling, mind body approaches, psychotherapy and medication next to each other, not against each other.

I give the guideline here in its broad outline. Some details I have from secondary accounts, which is why I put them cautiously.

Anyone still hearing today that there is nothing binding on functional dyspepsia is simply not up to date.

The two faces: fullness after eating, or burning independent of it

Ask yourself once: is your symptom coupled to the meal or not?

This single question separates the two subgroups more cleanly than any device. It is also the question that is skipped too quickly in many consultations, because both pictures end up under the same word.

Why is this distinction worth making if the diagnosis is the same in the end? Because it describes two very different worlds of experience. In the meal related type everything revolves around portions, pace and the question of whether you still enjoy eating at all. In the pain type everything revolves around burning, pressure and the fear that something is there after all.

And because the guidelines assign the treatment options differently. Whether that holds up against the data is a story of its own, and it comes further down.

The accompanying symptoms that are allowed to belong

The European consensus of 41 experts from 22 countries stated explicitly in 2021 which complaints are allowed to belong without breaking the diagnosis: a bloated feeling in the upper abdomen, nausea and belching.

That is more important than it sounds. Many people think that constant fullness and belching are a different problem. They often belong to the same picture.

What does not belong is everything that takes place below the navel. Abdominal pain that changes with the bowel movement belongs in another category. That is irritable bowel syndrome, and having both together is still common.

Air in the belly also has an article of its own, because it often has quite different roots than upper abdominal pressure. If a bloated belly is what mainly troubles you, this may take you further: where the air comes from.

What happens in the body: the fundus, the volume and the duodenum

If you want to know why three bites are enough, you need to know a reflex that hardly anyone has ever heard of.

The stomach is not a rigid sack. Its upper part, the fundus, relaxes while you eat and makes room before anything arrives. This is called accommodation. A good host clears the hallway before the guests come.

When this reflex turns out too weak, the food arrives in a space that has not grown yet. Pressure rises immediately, and satiation reports in far too early.

The second mechanism concerns not the space but the volume. Every stomach reports distension to the brain. In some people the dial for that report is turned up. The same portion, a different experience.

And gastric emptying? It stands at the very front of almost every guidebook and deserves a place, but not the first one. A meta-analysis of 25 evaluable studies with more than 6,000 participants found only loose associations where measurement technique was clean: nausea with an odds ratio of 1.6, vomiting 2.0, abdominal pain 1.5, early satiation and fullness 1.8.

Translated: slow gastric emptying can contribute to your symptoms. It does not explain them on its own.

And now the part that turns the matter around

The most interesting trail of the last decade and a half does not lead into the stomach. It leads one step further, into the duodenum.

That is the roughly 25 centimetre passage behind the stomach outlet. This is where the food pulp lands first, this is where it is measured how acidic and how fatty it is. From there the signals go back that determine how quickly the stomach passes things on and when satiation is reported.

So the duodenum is the control room, the stomach is the waiting room. And in this control room, in a subset of those affected, something turns up that you would not expect there.

Eosinophils are white blood cells from the parasite defence and allergy department. They do not indicate a wound, they indicate an immune system that is busy at this spot. Quietly, but persistently.

In the same Swedish sample a clean difference showed up: in functional dyspepsia the eosinophils were raised, in irritable bowel syndrome the mast cells were. Two related pictures, two different cell types. More on mast cells is in the article on mast cell activation.

When it started after an infection, and what stress has to do with it

There is a sentence I often hear in my consultations, usually half apologetically: ever since that stomach bug two years ago it has never fully gone away. People say it quietly, because they suspect it sounds like an excuse. It is not an excuse, it is a described pattern with a number attached.

For comparison: for post infectious irritable bowel syndrome the same odds ratio was 3.51. The details are in the article on irritable bowel syndrome.

And then there is the question almost everyone gets asked at some point, usually in a friendly tone that still stings: could this not be psychological? I answer it with two studies that point in different directions. Both are well done, both are true.

And now you know why the question about the psyche is neither an insult nor an explanation. It is one of several trails, and it does not rule out the others.

What else it can be: the honest differential

Before functional dyspepsia goes on the label, other things have to be ruled out. Not all of them are rare, and some are regularly confused. I go through the list briefly, each topic with two sentences and a link.

Functional dyspepsia and gastroparesis: the border is more permeable than assumed

Gastroparesis is delayed gastric emptying as a condition in its own right. It has an article of its own: gastroparesis, when the stomach is too slow. Only one number belongs here, and it leaves many people speechless.

What the diagnostics can do and where they stop

Does everyone with upper abdominal pain really need a gastroscopy? This is one of the most frequently asked questions, and the answer is uncomfortable because it comes in two parts.

No, not everyone. And yes, some absolutely and quickly.

The guidelines tie this distinction to two things: to the red flags and to age. Both together, not one alone. And there is a very good reason for that.

The American and Canadian guideline recommends endoscopy from the age of 60, earlier where the risk of stomach cancer is raised. The 2020 Lancet seminar names 55 years or concerning features. The European consensus considers endoscopy obligatory for a secure diagnosis, but regards a treatment trial without endoscopy as defensible in primary care when there are no red flags. The German guideline of 2025 makes it dependent on severity, duration and red flags.

What has been tested in studies, with the numbers behind it

Now comes the part where many guidebooks turn vague. They write that something is effective and leave open how effective. I consider these numbers important, because they protect you from two disappointments: from the fact that a medication does not do everything, and from throwing away something usable too early.

The number that carries the most weight here is called number needed to treat, NNT for short. It says: this many people have to be treated for one additional person to benefit. The smaller the number, the larger the effect.

Helicobacter pylori: a small effect that can last

Acid blockers: a small effect, surprising details

And then there is a finding on acid blockers that makes the matter more complicated.

Prokinetics: the best number on the weakest foundation

Prokinetics are meant to stimulate gastric movement. The meta-analysis of 29 placebo controlled trials names an NNT of 7, independent of subgroup and origin. Sounds good. Then come the limitations: heterogeneity of 91 percent, a GRADE rating of very low, and quality of life did not improve alongside. A number you cannot feel in everyday life is a difficult number.

On top of that comes a second point that does not show up in the bare NNT. These substances are prescription only, and some of them have received restrictions on use that have to do with heart rhythm and the nervous system. So the same applies here as to everything else in this section: start, duration and end belong in medical hands, not in a self experiment.

Neuromodulators: the biggest misunderstanding

When a low dose antidepressant is suggested after several attempts, many people hear something other than what is meant. They hear: you are depressed, and your gut is imagined.

Something else is meant. At low doses, tricyclic substances intervene in pain processing, at the nerve pathways between gut and brain. That is why they are called neuromodulators here.

The meta-analysis of 13 trials with 1,241 people names an NNT of 6, with the benefit limited to tricyclics and antipsychotics. And it is honest: looking only at the trials that had excluded people with an accompanying affective disorder, no benefit remained. Side effects were more frequent, with a number needed to harm of 21.

Plants: several studies, small effects, honest limitations

Two plant routes have been studied in randomised form. One is the set combination of peppermint oil and caraway oil in enteric coated capsules. In a trial with 96 people, pain intensity fell by 40 percent after 28 days compared with 22 percent on placebo. In a newer trial with 114 people the combination was better than placebo in both subgroups.

The other route is herbal combination preparations made from several extracts. In a multicentre trial with 315 people the difference from placebo was significant but small: 6.9 versus 5.9 points in the symptom score. In a smaller trial with 120 people and a six plant variant, after eight weeks 43.3 percent on the active preparation and 3.3 percent on placebo reported symptom freedom.

Why a mixture can act in opposite ways at two sites of the stomach has been shown by a tissue study: in guinea pig preparations the mixture relaxed the upper part of the stomach and at the same time increased movement in the outlet region. That is tissue in the laboratory, not a human being. Such findings explain, they document nothing for your everyday life.

Psychological approaches and the microbiome hint

Nine small randomised trials on psychological approaches give a standardised mean difference of minus 1.33. That looks large. Only three had a sham treatment arm, the risk of bias is correspondingly high, and the Lancet seminar explicitly calls the role of these approaches uncertain.

Best studied is gut directed hypnosis. In a trial with 126 people, the symptom score fell in the long term by a median of 73 percent under hypnosis, and by 43 percent under standard drug treatment. That is the size of the change, not the proportion of people who got better. And of the 126 randomised, only 79 completed all phases, which puts the numbers into perspective further. Striking: in the hypnosis group nobody started medication during follow up, in the comparison groups 82 and 90 percent did. Something like this can hardly be blinded. More under gut directed hypnotherapy.

And a single finding on the microbiome: in a study from Hong Kong with 86 people meeting Rome III criteria, after eight weeks 78 percent on rifaximin compared with 52 percent on placebo reported adequate relief, more markedly in women than in men. One centre, no replication.

The frame belongs with it: rifaximin is prescription only and licensed in Germany for hepatic encephalopathy and travellers diarrhoea, not for functional dyspepsia. Use here would be off label. And every course of antibiotics brings its own risks, among them diarrhoea caused by Clostridioides difficile and the development of resistance. So this is a hint, not a recommendation, and nothing for a self experiment. On small intestinal bacterial overgrowth in general: SIBO.

What everyday life can contribute, without building yourself a list of bans

At some point almost everyone reaches the moment when the list of deleted foods is longer than the list of allowed ones. And the belly is still not quiet.

I consider this path one of the most damaging in functional complaints. It costs joy, social life and nutrients and often brings less than one single targeted change. What do the data say? Less than the guidebooks suggest.

The alcohol finding is remarkable. Almost every guidebook names it as a trigger, the systematic review classifies the data as unclear. That does not mean alcohol is harmless. It only means the studies do not carry that statement. What else it can do in the gut is described under alcohol and the gut.

And why are dietary statements in functional complaints so wobbly? A second paper by the same group examined 40 studies for whether the recording period for food and the one for symptoms match at all. In 10 percent they did not match at all. And only 12 of 40 studies used a validated instrument for symptom recording.

So the problem often lies in the methodology, not on the plate. That is why I consider your own carefully kept diary more informative than a general list. This has not been compared, it is my conclusion from the criticism of the survey methods.

Common questions about functional dyspepsia

These are the questions I hear most often, in the consultation room and in letters. The answers draw on the sources at the end of this article.

Where the upper abdomen connects to the rest of the body

Functional dyspepsia rarely stands alone. It hangs on nutrition, on sleep, on load, on other intolerances and on how the immune system in the gut is currently working. If you want to read further, these are the next sensible steps.