Why anxiety lands in your stomach

A man in his thirties came to see me about his bowels: cramping most mornings, an urgent dash to the loo before any meeting, days of feeling bunged up in between. Halfway through he mentioned, as an aside, that he had not felt properly relaxed since 2023.

He had booked about his gut. He had also, without meaning to, told me about his anxiety. That pairing turns up constantly, and it gets mishandled in one of two directions: waved away as just stress, or pinned on gut bacteria. Neither is right.

The short version

• Anxiety genuinely produces gut symptoms. The cramping and the urgency are real physiology, not imagination.
• Anxiety and irritable bowel syndrome overlap heavily, and the relationship runs in both directions.
• Talking therapy sits on the NHS guideline for stubborn IBS. It is a recognised treatment, not a consolation prize.
• The microbiome story is interesting and is not yet a treatment. No gut test can diagnose anxiety, and no probiotic has been shown to treat it.

Your gut sits on the same circuit as your alarm

When your body decides something is threatening, it makes fast decisions about where to send resources, and digestion is near the bottom of the list. Blood goes to muscle, the bowel is told either to hurry everything along or hold it still, and the nerves lining the gut become more sensitive to sensations they would normally ignore.

That is why anxiety produces nausea before an interview, a churning stomach at six in the morning, the urgent trip to the loo before something you are dreading. The NHS lists stress and anxiety among the recognised triggers for IBS flare-ups, alongside alcohol, caffeine and certain foods.

I labour this because people arrive braced to be told it is all in their head. The same goes for the chest tightness and dizziness in the physical symptoms of anxiety.

Being told your gut symptoms are stress-related is not the same as being told they are imaginary. It is a description of the mechanism, not a dismissal.

Anxiety and IBS keep close company

IBS affects between five and ten per cent of people worldwide. A meta-analysis pooling 73 studies found anxiety symptoms in around 39 per cent of people with IBS, roughly three times the odds compared with people without it.

Which one comes first

The honest answer is both. A twelve year population study found the traffic runs in both directions. Higher anxiety and depression at the start predicted IBS at follow-up, and among people who began with neither, having a functional gut disorder predicted more anxiety and depression later.

That matters practically. People want to settle whether it is really a gut problem or a head problem before accepting treatment for either. The question has no answer, and waiting for one costs months.

What I would want to rule out first

IBS is a positive diagnosis, not something to reach for because nothing else turned up. NICE suggests assessing for it when someone has had abdominal pain or discomfort, bloating or a change in bowel habit for at least six months, plus blood tests, including for coeliac disease, to exclude other causes.

Some symptoms are neither. The NHS advises seeing a GP if you have had symptoms for more than four weeks, and asking for an urgent appointment, or calling 111, about unexplained weight loss, bleeding from your bottom or bloody diarrhoea, or a hard lump or swelling in your tummy. Please do not sit on those while you work on your stress levels.

Therapy is on the guideline, not the fringe

NICE recommends considering referral for psychological therapy, including CBT and hypnotherapy, for people whose IBS has not responded to medication after twelve months and has settled into a continuing pattern.

Twelve months is a long stretch to spend with a churning stomach before anyone offers you a conversation. It is one reason our own sessions are 20 minutes rather than an hour: when each end of the loop feeds the other, what matters most is starting, and a session that fits round a working day is easier to start.

A 2025 network meta-analysis of 67 trials found several forms of CBT, and gut-directed hypnotherapy, made it less likely that IBS symptoms would fail to improve, compared with a waiting list. The authors are blunt about the limits: high risk of bias in the trials, signs of publication bias, and confidence in the findings rated low or very low throughout. Worth trying, then. Not a cure.

Where the gut health aisle has run ahead of the evidence

Fix your microbiome, fix your mood. You will have seen some version of it. The animal work behind the claim is real; the difficulty is the leap from a rodent study to a tub of capsules aimed at a human being.

A 2022 systematic review brought together 44 observational studies of gut bacteria in people with mental health conditions. It found no strong evidence that people with a mental disorder carry a different number or spread of gut bacteria from those without one. Studies were more consistent in finding differences in the overall mix of species, which is interesting and a long way from a treatment. The methods varied so much that the authors could not pool the results. And that review covered depression, bipolar disorder and schizophrenia, all better studied here than anxiety.

NICE's only word on probiotics is modest: if you choose to try them for IBS, take them for at least four weeks and watch what happens. That is permission, not a recommendation, and it concerns bowels rather than mood. No gut test can diagnose anxiety or tell you what to take for it. Anyone selling you one is ahead of the evidence.

Where I would actually start

Get the red flag symptoms checked, so that worry has somewhere to stop. Keep a rough record for a fortnight of symptoms, meals, sleep and the hardest days: the pattern tells you more than any single bad morning. NICE's dietary advice for IBS includes keeping tea and coffee to three cups a day and cutting back on alcohol, both of which also act on anxiety. Do not start an elimination diet alone: NICE is clear a low FODMAP diet should come from someone with expertise in dietary management.

And work on both ends of the loop rather than queueing them. Waiting for the gut to settle before you deal with the anxiety usually means dealing with neither.

This article is general information and is not a substitute for personal medical advice. If your symptoms are new, changing, or worrying you, please see your GP.