Introduction 

Diarrhoea is passing looser or more frequent stools than is normal for you.

It affects most people from time to time and is usually nothing to worry about. However, it can be distressing and unpleasant until it passes, which normally takes a few days to a week.

What causes diarrhoea?

There are many different causes of diarrhoea, but a bowel infection (gastroenteritis) is a common cause in both adults and children.

Gastroenteritis can be caused by:

• a virus – such as norovirus or rotavirus
• bacteria – such as campylobacter and Escherichia coli (E. coli), which are often picked up from contaminated food 
• a parasite – such as the parasite that causes giardiasis, which is spread in contaminated water

These infections can sometimes be caught during travel abroad, particularly to areas with poor standards of public hygiene. This is known as travellers' diarrhoea.

Diarrhoea can also be the result of anxiety, a food allergy, medication, or a long-term condition, such as irritable bowel syndrome (IBS).

Causes of diarrhoea 

Diarrhoea usually occurs when fluid cannot be absorbed from the contents of your bowel, or when extra fluid is secreted into yourbowel, causing watery poo.

Short-term diarrhoea

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

• a virus – such as norovirus or rotavirus
• 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 of short-term diarrhoea include:

• feelings of anxiety
• 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 to help 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 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.

What to do if you have diarrhoea

Most cases of diarrhoea clear up after a few days without treatment, and you may not need to see your GP.

However, diarrhoea can lead to dehydration, so you should drink plenty of fluids – small, frequent sips of water – until it passes. It's very important that babies and small children do not become dehydrated.

Your pharmacist may suggest you use an oral rehydration solution (ORS) if you or your child are particularly at risk of dehydration.

You should eat solid food as soon as you feel able to. If you're breastfeeding or bottle feeding your baby and they have diarrhoea, you should try to feed them as normal.

Stay at home until at least 48 hours after the last episode of diarrhoea to prevent spreading any infection to others.

Medications to reduce diarrhoea, such as loperamide, are available. However, these are not usually necessary, and most types should not be given to children.

Read more about treating diarrhoea.

When to see your GP

Contact your GP or call NHS 111 for advice if you're concerned about yourself or your child.

It's important to see your GP if the diarrhoea is particularly frequent or severe, or associated with other symptoms, such as:

• blood in your or your child's poo
• persistent vomiting
• a severe or continuous stomach ache
• weight loss
• signs of dehydration – including drowsiness, passing urine infrequently, and feeling lightheaded or dizzy
• your poo is dark or black – this may be a sign of bleeding inside your stomach

You should also contact your GP if your or your child's diarrhoea is particularly persistent, as this may be a sign of a more serious problem. In most cases, diarrhoea should pass within about a week.

Read more about when to contact your GP and diagnosing diarrhoea.

Preventing diarrhoea

Diarrhoea is often caused by an infection. You can reduce your risk by making sure you maintain high standards of hygiene.

For example, you should:

• wash your hands thoroughly with soap and warm water after going to the toilet and before eating or preparing food
• clean the toilet, including the handle and the seat, with disinfectant after each bout of diarrhoea
• avoid sharing towels, flannels, cutlery, or utensils with other household members

It's also important to practise good food and water hygiene while travelling abroad, such as avoiding potentially unsafe tap water and undercooked food.

Read more about preventing diarrhoea.