Diarrhoea

How serious is it?

Diarrhoea usually clears up in a couple of days and is not serious. However, it can be serious in babies and the elderly because of the risk of dehydration.

If diarrhoea is persistent or associated with symptoms such as blood, you should see your GP.

If your child is between three months and one year old, diarrhoea should last no longer than 48 hours. If it is any longer, contact your GP.

Diagnosing diarrhoea 

If you have acute (short-term) diarrhoea, the symptoms are very likely to settle down within a week and tests are usually unnecessary.

However, if your diarrhoea becomes more persistent or if you have other symptoms (such as blood in your stools, or dehydration) your GP may ask for a stool sample to investigate for bacteria or parasites.

Other tests for chronic diarrhoea may include blood tests or a sigmoidoscopy (a procedure that involves passing a thin fibre-optic tube, attached to a viewing lens, through the rectum to view the intestine).

If your child is between three months and one year old, diarrhoea should last no longer than 48 hours. If it is any longer, contact your GP.

Causes 

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

The stools can become watery for the following reasons:

• The lining of the gut becomes damaged by bacteria or viruses. This means the intestines are unable to absorb fluid from the bowel contents.
• Too much fluid is secreted into the bowel, causing 'secretory diarrhoea' . This is often a sign of bacterial infection.
• Bowel contents move through the gut too quickly, so the intestines do not have enough time to absorb fluid from the bowel contents. This is often caused by anxiety or some drugs.
• Food, such as lactose, is not absorbed properly, causing water to move out of the blood and into the bowel, to dilute the contents.

Acute diarrhoea

Short-term diarrhoea is usually a symptom of gastroenteritis, which is an infection of the bowel.

Gastroenteritis may be caused by:

• a virus, such as norovirus or rotavirus
• food poisoning - usually caused by salmonella, campylobacter or staphylococci bacteria
• an Escherichia coli bacterial infection, which causes secretory diarrhoea.
• antibiotics or
• contaminated food or water from a foreign country.

Other, short-term causes of diarrhoea include:

• emotional upset or anxiety
• drinking too much alcohol
• drinking too much much coffee or
• the side effect from some medicines.

Chronic diarrhoea

Chronic (persistent) diarrhoea can be caused by:

• a bacterial or viral infection
• laxatives
• poor diet (too much coffee, alcohol or sweets) and
• a long-term condition (see below).

Long-term conditions that cause diarrhoea include:

• ulcerative colitis
• Crohn's disease
• irritable bowel syndrome (IBS)
• lactose intolerance
• coeliac disease
• diabetes and
• pancreatitis.

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