Can Stress Cause Diarrhoea? The Gut–Brain Link

Can stress cause diarrhoea?

Yes. Stress is a recognised cause of short-term diarrhoea, along with infections, a change in diet and too much alcohol.¹ Many people know the feeling: loose, urgent bowel movements before an exam, an interview or a difficult conversation.

Why stress affects your gut

Your brain and your gut are in constant two-way contact through nerves, hormones and the immune system. Researchers call this the gut–brain axis. When you are stressed, the signals change, and the gut responds in several ways:^2,3

• Movement. Stress alters how fast food and waste travel through the bowel
• Sensitivity. The gut becomes more sensitive, so normal stretching and gas can feel painful
• Secretion. The bowel releases more fluid, which makes stools looser
• The gut lining and its bacteria. Stress makes the lining more leaky and affects the balance of gut bacteria

Diarrhoea happens when too much fluid is secreted into the stool or not enough water is absorbed from it.¹ Faster movement and extra secretion do exactly that.

Can stress cause constipation?

It can. Stress doesn’t push every gut in the same direction. Some people speed up, some slow down, and some swing between the two. All three patterns are seen in irritable bowel syndrome, where stress is one of the common triggers.⁴ Stress also disrupts the things that keep you regular, such as meals, sleep, exercise and time to use the toilet.

Other gut symptoms of stress

• Stomach cramps and bloating
• Nausea, or “butterflies”
• Loss of appetite, or eating more than usual
• Heartburn or reflux²

Is it irritable bowel syndrome?

If stress-related gut symptoms keep coming back, irritable bowel syndrome (IBS) is a possibility. The key symptoms are abdominal pain, bloating, and diarrhoea or constipation, or both in turn. Pain is often eased by going to the toilet.⁴

IBS is common. Healthdirect puts it at around one in five people, and women are affected more often than men.⁴ A worldwide survey of more than 73,000 adults, using stricter criteria, found that about 4 per cent met the definition, and that four in ten had some form of gut–brain disorder.⁵

The link with stress and mood is strong:

• A meta-analysis of 73 studies found that 39 per cent of people with IBS had anxiety symptoms and 29 per cent had symptoms of depression, about three times the odds seen in people without IBS⁶
• IBS is described as a stress-sensitive condition, where stress causes flare-ups and makes symptoms worse³

In IBS, blood tests, scans and camera tests come back normal. Your doctor needs to rule out other conditions before making the diagnosis.⁴

Stress and inflammatory bowel disease

Crohn’s disease and ulcerative colitis are different from IBS. They involve visible inflammation and damage in the bowel. Stress doesn’t cause them, but it may affect their course. In a Canadian study that followed 552 people for a year, high perceived stress was the only factor linked with flare-ups, more than doubling the odds.⁷

What helps

For a one-off bout

Most diarrhoea is mild and clears up in a few days without treatment. Drink plenty of fluids so you don’t get dehydrated, and ask a pharmacist before taking anything to stop it.¹

If it keeps happening

• Work on the stress. Slow breathing, exercise and sleep all calm the stress response. See stress and how to calm anxiety
• Psychological therapy. A network meta-analysis of 41 trials with more than 4,000 people found that cognitive behavioural therapy and gut-directed hypnotherapy both improved IBS symptoms. The authors cautioned that the trials were prone to bias, so the benefits may be overstated⁸
• Diet. A dietitian can help you find your trigger foods. For some people, that means a trial of a low FODMAP diet, which cuts down on certain poorly absorbed sugars⁴
• Fibre. Build up slowly towards 25 to 30 grams a day⁴

In an Australian trial of 74 people with IBS, six weeks of gut-directed hypnotherapy worked as well as the low FODMAP diet. About 70 per cent improved with either approach, and most kept the benefit six months later.⁹

When to see a doctor

Don’t put ongoing bowel changes down to stress without having them checked. See your doctor if you have:^1,4

• Diarrhoea that is ongoing or keeps returning
• Blood or mucus in your stool
• Unexplained weight loss
• A fever
• Diarrhoea that wakes you at night

Go to an emergency department for severe diarrhoea, heavy bleeding from the bowel, or signs of dehydration such as great thirst, a dry mouth and passing little urine.¹

References

1. healthdirect. Diarrhoea.
2. Konturek PC, Brzozowski T, Konturek SJ. Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. J Physiol Pharmacol. 2011;62(6):591-9.
3. Qin HY, Cheng CW, Tang XD, et al. Impact of psychological stress on irritable bowel syndrome. World J Gastroenterol. 2014;20(39):14126-31.
4. healthdirect. Irritable bowel syndrome (IBS).
5. Sperber AD, Bangdiwala SI, Drossman DA, et al. Worldwide Prevalence and Burden of Functional Gastrointestinal Disorders, Results of Rome Foundation Global Study. Gastroenterology. 2021;160(1):99-114.e3.
6. Zamani M, Alizadeh-Tabari S, Zamani V. Systematic review with meta-analysis: the prevalence of anxiety and depression in patients with irritable bowel syndrome. Aliment Pharmacol Ther. 2019;50(2):132-143.
7. Bernstein CN, Singh S, Graff LA, et al. A prospective population-based study of triggers of symptomatic flares in IBD. Am J Gastroenterol. 2010;105(9):1994-2002.
8. Black CJ, Thakur ER, Houghton LA, et al. Efficacy of psychological therapies for irritable bowel syndrome: systematic review and network meta-analysis. Gut. 2020;69(8):1441-1451.
9. Peters SL, Yao CK, Philpott H, et al. Randomised clinical trial: the efficacy of gut-directed hypnotherapy is similar to that of the low FODMAP diet for the treatment of irritable bowel syndrome. Aliment Pharmacol Ther. 2016;44(5):447-59.