Diarrhoea is when your bowel movements become more watery or more frequent than usual, or both. The stool may also contain mucus, pus, blood or excessive amounts of fat. Diarrhoea can often be accompanied by painful abdominal cramps and a generalised weakness.
Diarrhoea occurs when the lining of the intestine is unable to absorb fluid, or it actively secretes fluid.
Diarrhoea is most commonly caused by viruses passed from person to person, or by eating or drinking food or water contaminated with viruses or bacteria.
Other causes of diarrhoea include parasite infestation (e.g. amoebae), too much alcohol, a reaction to certain medicines, or a food intolerance.
Some diseases that affect the digestive tract can also cause diarrhoea and it is a common symptom of Crohn’s disease, ulcerative colitis, irritable bowel syndrome, gastrointestinal tumours, and malabsorption syndromes such as coeliac disease.
Preventing dehydration is the main focus of treatment in the initial stages of diarrhoea. Children and babies are particularly prone to dehydration when they have diarrhoea.
To combat dehydration, drink plenty of clear, lightly sweetened fluid. If you have nausea, try taking small sips of fluid often. Suitable fluids include salty, clear soups, diluted cordial and diluted fruit juice. It is very important to make sure that sugary drinks such as fruit juice are well diluted (at least 4 parts of water to one of fruit juice). Avoid tea, coffee, milk, cola drinks, carbonated drinks or alcohol.
Alternatively, drink a mixture which replaces lost salts and sugar (e.g. an oral re-hydration solution such as Gastrolyte, Hydralyte or Repalyte). These mixtures can be bought at a pharmacy and are especially recommended for children who have diarrhoea.
See your doctor if you have diarrhoea and:
If your baby has diarrhoea and is under 6 months old, take the baby to a doctor straight away.
If your child has diarrhoea, take them to a doctor straight away if they have:
The doctor may send a stool sample to the laboratory for analysis and will also perform a general health assessment. They will be looking for signs of dehydration or indicators that the diarrhoea may be caused by something other than a bug.
Dehydration may be treated with oral fluids or, if severe, with intravenous fluids (i.e. into a vein, via a drip). Antibiotics are prescribed only in cases of severe diarrhoea and when the doctor knows what type of bacterium or parasite is to be treated. He or she may occasionally prescribe some medicine to slow down the diarrhoea in adults (this type of medicine is not used in children).
While you have diarrhoea, avoid consuming milk and milk products, and fatty, very sweet or high-fibre foods. Resume eating solid food slowly and choose foods that are low in fat. This includes crackers, stewed apples, plain rice, bananas or toast.
Some types of diarrhoea can very easily be passed on. It is important that children do not go to school or childcare when they have diarrhoea.
Wash your hands with warm water and soap thoroughly after going to the toilet and before food preparation — teach your children to do the same. Hand sanitisers are useful when you are not near a sink. Sterilise and wash nappies of young children who have diarrhoea separately to other clothes.
Diarrhoea can affect the way that some medicines (such as the contraceptive pill) are absorbed. If you take the contraceptive pill and develop diarrhoea, you should use a back-up method of contraception, such as condoms, until your next menstrual period because the diarrhoea may make the pill less effective. If you are taking any other regular medicine, talk to your doctor about the effects that diarrhoea may have had on its effectiveness.
Last Reviewed: 02 December 2009