What is diarrhoea?

Diarrhoea is the passing of frequent, loose or liquid stools. The number of times a person usually opens their bowels varies greatly - three times a day may be normal for one person, while three times a week may be normal for another. Diarrhoea can be acute, starting suddenly and lasting a short time, or chronic, lasting a long time.

A doctor should be consulted after a few days if the diarrhoea does not settle, or earlier if it is severe and causing dehydration. A doctor should be consulted sooner if the person affected is elderly or very young (under two years).

What are the symptoms of diarrhoea?

The main symptom is an increase in the usual number of bowel movements, resulting in frequent, loose or liquid stools. Bowel movements are often preceded by cramping abdominal (tummy) pain, which eases after the stool is passed. Sometimes there is an accompanying high temperature and in severe cases there may also be blood or mucus in the stools.

What causes acute diarrhoea?

Diarrhoea is a symptom of other conditions and is not a disease in itself. It can be caused by a variety of illnesses and conditions, the most common of which is gastroenteritis. Gastroenteritis is usually caused by a viral infection and is passed easily from one person to another. It can also be caused by bacteria in food - when this happens it is often called food poisoning.

Some drugs, such as antibiotics, can cause diarrhoea as a side effect.

Anxiety can also cause diarrhoea temporarily. Excess alcohol can cause diarrhoea as a result of large volumes of fluid in the bowel.

What causes chronic diarrhoea?

Chronic diarrhoea can be a symptom of other illnesses, particularly those affecting the digestive system. Examples include Crohn's disease, irritable bowel syndrome (IBS), diverticulitis and infection with the HIV virus.

Tropical diseases such as cholera, dysentery and giardiasis can also cause chronic diarrhoea. In the developing world these diseases are often fatal in small children.

Some stomach operations may cause chronic diarrhoea.

Are there any tests necessary?

In some cases of acute diarrhoea your doctor may order a stool test to find out what is causing it. Examples of instances where a stool test may be necessary include the following:

  • Acute diarrhoea following recent return from abroad, particularly from countries where tropical diseases are known to exist.
  • Severe diarrhoea accompanied by other symptoms such as a temperature and feeling generally unwell.
  • Severe diarrhoea lasting more than a few days.
  • The presence of blood in the stools.

In chronic diarrhoea further diagnostic tests, such as a barium enema, sigmoidoscopy or colonoscopy, may be carried out - your doctor will explain about these tests if you need to have one. These tests may confirm the cause of the diarrhoea, which may not necessarily be an infection.

What treatment is available?

Rehydration is very important. Electrolyte solutions are used in acute diarrhoea to replace lost fluids and salts and are usually available as flavoured powder in sachets that needs to be mixed with water before taking (eg, Dioralyte®, Electrolade®, Rapolyte®). Electrolyte solutions do not cure the diarrhoea but are necessary to prevent dehydration, which can be dangerous, particularly in the elderly and young children. Medical advice should always be sought before treating the elderly and young children.

Adsorbents help to adsorb (mop up) toxic substances in cases of infective diarrhoea and are also used in chronic diarrhoea. Examples include methylcellulose (Celevac®).

Opiate derivatives act by slowing down movement through the intestine and should only be taken as a short-term solution. These can be purchased over the counter from a pharmacist. Examples include loperamide (eg, Imodium®). 

Anti-hypersecretory agents reduce the secretion of water and electrolytes in the intestine. Examples include racecadotril (Hidrasec®).

Occasionally, antibiotics may be prescribed, usually for diarrhoea associated with a tropical disease. Antibiotics are not usually given in cases of food poisoning.

Self-help measures:

  • Avoid dehydration; drink clear fluids, preferably those containing electrolytes and an energy source such as glucose. Simple lemonade is an option but rehydration sachets can be bought over the counter from a pharmacist or obtained on prescription from your doctor.
  • Good hygiene, particularly washing your hands thoroughly after going to the toilet, is essential in case the diarrhoea is infectious.
  • Do not prepare food for other people, especially babies and old people while you have acute diarrhoea.
  • A carbohydrate diet that includes boiled potatoes or boiled rice may help.
  • If the diarrhoea does not resolve after a few days, seek medical advice.

Fact sheet provided by MIMS

Date last reviewed: June 2014

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