How stress affects your digestion: what happens in your gut, and what helps

A knot in your stomach before an interview. Butterflies before a big moment. A sudden dash to the toilet before an exam. Most of us have felt stress in our gut before we have noticed it in our head.

This is not imagination. It is physiology. As a gastroenterologist, I hear about it every week. Here is what stress does to your digestion, why it happens, and what the evidence says helps.

Your gut and brain are wired together

Your digestive system has its own large network of nerves, sometimes called the "second brain". It is in constant two-way conversation with the brain in your head. Scientists call this the gut–brain axis [1, 2].

The conversation runs along several lines at once:

• Nerves: the vagus nerve carries signals in both directions between the brainstem and the gut, and most of its fibres carry information up to the brain [3].
• Hormones: the stress hormone system, which releases cortisol, affects gut movement, secretion and sensitivity [1].
• The immune system: immune cells in the gut lining respond to stress signals [1].
• Gut microbes: the bacteria in your gut both respond to stress and send signals of their own [2].

Because the lines run both ways, stress can change how your gut works, and an unsettled gut can feed back to how you feel.

What happens in your gut when you are stressed

When you sense a threat, your body switches towards "fight or flight". Blood is directed to your muscles, your heart speeds up, and digestion becomes a lower priority. That made sense when the threat was physical. It is less helpful when the threat is an inbox.

Research has shown a consistent pattern. A stress hormone called corticotropin-releasing factor slows the emptying of the stomach while speeding up movement in the large bowel [4]. At the same time, stress can make the gut more sensitive, so normal sensations register as discomfort [1, 5].

Stress slows the stomach and speeds up the bowel, which is why nausea and a sudden need for the toilet so often arrive together.

That combination explains many familiar experiences:

• Butterflies, nausea or loss of appetite: the stomach empties more slowly.
• Indigestion or heartburn: stress and anxiety can bring on or worsen indigestion [6].
• Urgency or loose stools: the large bowel speeds up.
• Bloating or cramps: the gut is more sensitive to normal amounts of gas and movement.
• Comfort eating, or skipping meals: stress changes appetite in different ways in different people.

The NHS lists stomach problems among the common physical signs of stress, alongside headaches, muscle tension and a faster heartbeat [7].

Short bursts versus long-term stress

A short burst of stress, such as nerves before a presentation, usually settles once the moment passes. Your digestion returns to normal as the "rest and digest" side of your nervous system, led by the vagus nerve, takes over again [3].

Long-running stress is different. When stress hormones stay raised for weeks or months, the changes in gut movement, sensitivity and even the balance of gut microbes can persist [1, 2, 5]. Poor sleep, irregular meals and more alcohol, which often come with stress, add to the effect.

What helps

None of these replace medical advice, but each has evidence behind it and is safe for most people.

1. Slow your breathing. Breathing at around six breaths a minute, with a longer out-breath, shifts the nervous system towards its rest and digest state within minutes. A systematic review found slow breathing consistently increased markers of vagus nerve activity [8]. Try it for five minutes before a stressful event or a meal.
2. Move every day. Regular physical activity reduces stress and supports regular bowel habits. UK guidelines recommend at least 150 minutes of moderate activity a week [9].
3. Protect your sleep. Poor sleep and an unsettled gut often go together. Our article on sleep and gut health explains why.
4. Eat without rushing. Regular meals, eaten sitting down and away from your desk, give your gut the cue to switch into digestion.
5. Go easy on alcohol and nicotine. The NHS advises against using them to cope with stress, as they can make things worse [7].
6. Talk to someone. Sharing how you feel with a friend, family member or professional is one of the NHS's first recommendations for stress [7].

When to see your GP

Stress is a common reason for an upset stomach, but it should never be assumed to be the cause. See your GP if:

• your symptoms keep coming back, or last more than three weeks [10]
• you notice blood in your poo, or black or very dark poo [10]
• you lose weight without trying [6, 10]
• you have difficulty swallowing, or keep being sick [6]
• you have severe or worsening tummy pain [6]

If you have heavy bleeding from your bottom that will not stop, call 999 or go to A&E [10].

The bottom line

Stress affects your digestion because your gut and brain are wired together. Stress hormones slow the stomach, speed up the bowel and turn up the volume on gut sensations. The same connection works in reverse: slow breathing, movement, sleep and unhurried meals help the rest and digest system take over again.

To understand the nerve at the centre of this, read what the vagus nerve does, or start with what the gut–brain axis is. To follow our work, join our Founding Community.

Frequently asked questions

Can stress really affect your stomach? Yes. Your gut and brain are connected through nerves, hormones and the immune system [1]. Stress hormones can slow the stomach, speed up the large bowel and make the gut more sensitive, which is why stress can bring on nausea, indigestion or a sudden need for the toilet [4, 5].

Why do I need the toilet when I'm nervous? Stress hormones, especially one called corticotropin-releasing factor, tend to speed up movement in the large bowel while slowing the stomach [4]. That combination can cause urgency or loose stools before a stressful event.

How do I calm my stomach when I'm stressed? Slow breathing, at around six breaths a minute, shifts the nervous system towards its rest and digest state within minutes [8]. Regular physical activity, enough sleep, unhurried meals and less alcohol also help over time [7, 9].

When should I see a doctor about stomach symptoms? See your GP if symptoms keep coming back or last more than three weeks, or if you notice blood in your poo, unexplained weight loss, difficulty swallowing or repeated vomiting [6, 10]. These need checking whatever you think the cause is.

Declaration of interest: The author is the founder of CortiAura, a company developing vagus nerve technology. This article is educational and makes no claims about any CortiAura product.

References

1. Mayer EA. Gut feelings: the emerging biology of gut–brain communication. Nature Reviews Neuroscience 2011;12(8):453–466.
2. Cryan JF, O'Riordan KJ, Cowan CSM, et al. The microbiota-gut-brain axis. Physiological Reviews 2019;99(4):1877–2013.
3. Breit S, Kupferberg A, Rogler G, Hasler G. Vagus nerve as modulator of the brain–gut axis in psychiatric and inflammatory disorders. Frontiers in Psychiatry 2018;9:44.
4. Taché Y, Bonaz B. Corticotropin-releasing factor receptors and stress-related alterations of gut motor function. Journal of Clinical Investigation 2007;117(1):33–40.
5. Konturek PC, Brzozowski T, Konturek SJ. Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. Journal of Physiology and Pharmacology 2011;62(6):591–599.
6. NHS 111 Wales. Indigestion. Accessed October 2026.
7. NHS 111 Wales. Stress. Accessed October 2026.
8. Zaccaro A, Piarulli A, Laurino M, et al. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience 2018;12:353.
9. Department of Health and Social Care. UK Chief Medical Officers' physical activity guidelines. 2019.
10. NHS 111 Wales. Cancer of the colon, rectum or bowel. Accessed October 2026.

© 2026 CortiAura. Text and illustrations may not be reproduced without permission.