7 common causes of chronic diarrhoea

Written by: Dr Evangelos Russo
Published: | Updated: 21/05/2019
Edited by: Bronwen Griffiths

Diarrhoea is when you pass looser and more frequent stools than usual. Most people will experience this from time to time, and usually the cause is nothing to be concerned about, however, if you are suffering from diarrhoea for several weeks, this is classed as chronic diarrhoea and it should be investigated by a doctor. Dr Evangelos Russo is a leading gastroenterologist and an expert in diagnosing the underlying causes of chronic diarrhoea. Here he explains the seven most common causes of chronic diarrhoea in the Western world.

Common causes of diarrhoea in the Western world include the following:

1) Infection:

This can typically be caused by viruses or bacteria. Infections can be transmitted through contaminated food or from person to person, and outbreaks in confined environments are quite common (most of us have heard of rotavirus outbreaks in cruise ships or hospitals). The majority of these are usually self-limiting for a few days, and they do not require specific treatment. Certain intestinal infections can persist for longer periods and cause chronic diarrhoea, especially in the elderly and people with weakened immune systems (immunocompromised).

2) Medications:

This is a common cause of diarrhoea that is often overlooked. There is a large number of drugs that can cause chronic diarrhoea, including several antibiotics, antacids, medications for high blood pressure, anti-inflammatories and others. A careful medication history is crucial in assessing patients with persistent diarrhoea as this can be easily addressed by stopping the offending tablets.

3) Inflammatory bowel disease (IBD):

IBD , which comprises Crohn’s disease, ulcerative colitis and microscopic colitis are inflammatory conditions of the gastrointestinal tract which are encountered with increasing frequency. Diarrhoea, which often contains blood, is frequently the cardinal symptom in these conditions. IBD is diagnosed with a colonoscopy, an examination where the bowel is inspected with the use of a flexible camera, during which small samples from the lining can be obtained and examined under the microscope. IBD should always be considered and ruled out in young people with persistent diarrhoea, especially if this is associated with abdominal pain and weight loss.

4) Irritable bowel syndrome (IBS):

IBS is a very common condition associated with changes in bowel habit, bloating and abdominal pain. Diarrhoea is a common manifestation. Whilst we know that it is generally a benign condition not driven by an underlying inflammation or other serious pathology, the symptoms can be particularly persistent and distressing.

Unfortunately, the exact cause of IBS has not been uncovered yet, but research is currently focused on identifying specific gut microbial profiles and dietary factors that can either exacerbate or protect against the syndrome. We also know that stress can contribute significantly to IBS symptoms.

Potential treatment strategies include dietary interventions, as well as pharmacological options for more persistent cases. There is also evidence that hypnotherapy, behavioural therapy and complimentary approaches can also be of benefit in some patients.

5) Bile acid diarrhoea:

This is another common cause of chronic diarrhoea that is frequently overlooked. Bile acids are produced by the liver and secreted in the upper gut in response to a meal to help with its digestion. Normally, these are reabsorbed in the lower small bowel in order to enter the same cycle again. If this cycle is interrupted, bile acids enter the large bowel which can cause chronic diarrhoea by coming into contact with its lining. Once this is diagnosed, it is usually relatively straightforward to manage with the use of medications that prevent that contact between bile acids and the colonic wall.

6) Food intolerances or coeliac disease:

Food intolerances are also quite common. A subset of people readily develop symptoms including cramping, bloating and diarrhoea in response to dairy products. This can be attributed to lactose intolerance. Wheat is another common trigger, a severe form of which is coeliac disease. Coeliac disease is seen in up to 1% of the population and is caused by inflammation driven by gluten, a protein commonly found in wheat, rye and barley. A careful dietary history and screening blood tests for coeliac disease form part of the routine assessment of patients with diarrhoea.

7) Pancreatic insufficiency:

Issues with the function of the pancreas, a gland located behind the stomach which has a crucial role in digestion, can cause chronic diarrhoea. This is due to inadequate production or secretion of digestive enzymes, in response to fatty food in particular. The commonest, but by no means sole cause of pancreatic insufficiency, is chronic alcohol abuse. In addition to being harmful to the pancreas, alcohol also has a direct deleterious effect on intestinal cells, which in turn can cause chronic diarrhoea.


If you have been suffering from frequent bouts of diarrhoea, make an appointment with an expert so that you can be treated or diagnosed.

Dr Evangelos Russo

By Dr Evangelos Russo

Dr Evangelos Russo is a skilled gastroenterologist based in London. He specialises in diagnostic and therapeutic endoscopy, colonoscopy, and polypectomy, and is an expert in treating inflammatory bowel disease (IBD), chronic diarrhoea, and acid reflux, among other conditions.

Dr Russo gradutated from University College London in 2003. He completed further training on the North West Thames rotation, while also earning a PhD in translational medicine from Imperial College London for his research on imaging techniques in the diagnosis and treatment of Crohn's disease.

With his appointment as Consultant Gastroenterologist at Imperial College Healthcare NHS Trust, he has established himself as a core member of the multidisciplinary team that treats lower gastrointestinal (GI) cancer. He has been involved extensively in research into IBD and his work has been widely published. He is also an honorary clinical lecturer at Imperial College London.

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