Causes

Diarrhoea usually occurs when fluid can't be absorbed from the contents ofyour 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) , whichcanbe caused by: a virus such as norovirus orrotavirus bacteria such as campylobacter, Clostridium difficile (C. difficile) , Escherichia coli (E. coli), salmonella or shigella; these can all cause food poisoning parasites such as the Giardia intestinalis parasite that causes giardiasis Other possible causes ofshort-term diarrhoea include: feelings ofanxiety drinking too much alcohol a food allergy appendicitis damage to the lining of the intestines as a result of radiotherapy Medicines Diarrhoea can also sometimes be a side effect of a medication, including: antibiotics antacid medicines that contain magnesium some chemotherapy medicines non-steroidal anti-inflammatory drugs (NSAIDs) selective serotonin reuptake inhibitors (SSRIs) statins cholesterol-lowering medicines laxatives medicine used tohelp empty your bowels 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: irritable bowel syndrome (IBS) a poorly understood condition that affects the normal functions of the bowel inflammatory bowel disease conditions that cause the gut to become inflamed, such as Crohn's disease and ulcerative colitis coeliac disease a digestive condition where you have an adverse reaction to gluten bile acid malabsorption where bile produced by the liver builds up in the digestive system chronic pancreatitis inflammation of the pancreas diverticular disease where small bulges or pockets develop in the lining of the intestine bowel cancer this can cause diarrhoea and blood in your stools Persistent diarrhoea can also sometimes occurafter surgery on the stomach, such as a gastrectomy .