Frequent passing of faeces with a high water content, causing increased volume. Because the normal pattern of bowel evacuation varies considerably this should be taken into account before diarrhoea is diagnosed (three times per day can be normal; the important factor is whether it is exceptional). Sometimes diarrhoea contains blood, mucus or pus, which may help to identify the cause. The condition can be acute, severe or even chronic; there are many causes, but it must be pointed out that despite the variety of possible causes, most cases of diarrhoea result from eating the wrong or too much food or frbm a slight infection of the stomach and intestines, and clear up of their own accord without medical assistance. The following are the important groups of causes: infections (including food poisoning, typhoid, dysentery, salmonella), malabsorption (digestive troubles occurring in galactosaemia, thrush, after operations etc.), pancreatic disorders (e.g. chronic inflammation), restricted bile discharge (for example as a result of gallstones), metabolic disturbances (e.g. hyperthyroidism), food allergies, use of certain antibiotics, misuse of laxatives, aspeci- fic inflammation such as Crohn’s disease or ulcerative colitis, and psychcological causes (nervousness). Severe diarrhoea (possibly with vomiting) can lead to complications such as mineral deficiency, dehydration (particularly in the young and the elderly) and acidification of the blood (acidosis). Chronic forms cause malnutrition, weight loss and vitamin deficiency. Treatment and the necessity to consult a doctor depend on the severity of the diarrhoea; the cause may well be known (ulcerative colitis, operation etc.), allowing the doctor to proceed immediately with treatment. If bacterial infection is suspected a faecal culture can be prepared.