Diarrhoea usually occurs when fluid cannot be absorbed from the contents of your bowel, or when extra fluid is secreted into your bowel, causing watery faeces.
Diarrhoea is usually a symptom of gastroenteritis (a bowel infection). It can be caused by:
Diarrhoea caused by contaminated food or water while visiting a foreign country is often known as travellers' diarrhoea.
Other possible causes of short-term diarrhoea include:
Diarrhoea can also sometimes be a side effect of medicines, including:
The patient information leaflet that comes with your medicine should state whether diarrhoea is a possible side effect.
You can also use the medicines A-Z to find out more about your medicine.
Conditions that can cause persistent diarrhoea include:
Persistent diarrhoea can also sometimes occur following a gastrectomy. This is a surgical operation to remove part of the stomach, for example as a treatment for stomach cancer.
Diarrhoea can also sometimes be caused by bariatric surgery (weight loss surgery used as a last resort to treat people who are dangerously obese).