Causes of diarrhoea 

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 poo.

Short-term diarrhoea

Diarrhoea is usually a symptom of a bowel infection (gastroenteritis), which can be caused by:

Other possible causes of short-term diarrhoea include:


Diarrhoea can also sometimes be a side effect of a medication, including:

The patient information leaflet that comes with your medicine should state whether diarrhoea is a possible side effect.

Long-term diarrhoea 

Conditions that can cause persistent diarrhoea include:

Persistent diarrhoea can also sometimes occur after surgery on the stomach, such as a gastrectomy. This is an operation to remove part of the stomach – for example, as a treatment for stomach cancer.

Page last reviewed: 26/11/2014

Next review due: 26/11/2016