Medical Encyclopaedia › Diarrhoea (short definition)
In brief: Diarrhoea means more than three unformed or liquid bowel movements a day. Acute diarrhoea is usually caused by viruses or bacteria and generally subsides by itself within a few days.
Causes
The most common causes are gastrointestinal infections with noroviruses or rotaviruses and bacterial food poisoning. Travellers’ diarrhoea, antibiotics, food intolerances such as lactose intolerance, stress and chronic bowel diseases are also possible. If diarrhoea lasts longer than two to four weeks, it is called chronic diarrhoea.
Replacing fluid
The most important measure is to replace lost fluid and salts. Ready-made oral rehydration solutions from the pharmacy contain salts and glucose in a balanced ratio and are particularly suitable for children and older people. Cola and pretzel sticks are considered unsuitable, as they do not adequately compensate for the loss of minerals. As soon as appetite allows, easily digestible food can be eaten again.
Medicines
Loperamide slows bowel movement and can be useful in the short term in adults, for example when travelling. It is not suitable in the case of fever, bloody diarrhoea or for small children. Antibiotics are only necessary for certain bacterial infections.
When to see a doctor?
Medical advice is needed for infants, young children and older people with severe fluid loss, in the case of high fever, blood in the stool, severe abdominal pain, signs of dehydration such as drowsiness or passing little urine, and for diarrhoea after long-distance travel.
Related terms in the encyclopaedia
Oral rehydration solution, Dehydration, Loperamide, Gastroenteritis, Antidiarrhoeals, Lactose intolerance
Sources
- Deutsche Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten (DGVS): S2k-Leitlinie Gastrointestinale Infektionen
- IQWiG: gesundheitsinformation.de – Gesundheitsinformationen des Instituts für Qualität und Wirtschaftlichkeit im Gesundheitswesen
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.