Overview
Diarrhoea is defined as passing loose or liquid stools three or more times in 24 hours. Most cases are short-lived, caused by infection, and resolve without treatment. Persistent or bloody diarrhoea needs medical investigation.
How common is it?
Diarrhoea is one of the most common medical complaints worldwide. Most adults experience it several times per year.
Causes and risk factors
The most common cause is a viral or bacterial gut infection causing rapid passage of water into the bowel or impairing its absorption. Chronic diarrhoea has a wider range of causes.
Common risk factors
- Viral gastroenteritis (norovirus, rotavirus)
- Bacterial infection from contaminated food or water
- Antibiotics (disrupting gut bacteria)
- Food intolerance (lactose, fructose)
- Irritable bowel syndrome
- Inflammatory bowel disease (Crohn's, UC)
- Anxiety and stress
Symptoms
- Loose or watery stools
- Urgent need to pass stool
- Abdominal cramps and pain
- Bloating
- Nausea
- Fever with infectious causes
- Blood or mucus in stool in more serious cases
When to see a doctor
See a doctor for diarrhoea lasting more than 7 days, blood or mucus in stools, signs of dehydration (dark urine, dizziness, dry mouth), or if you are very young, elderly, pregnant, or immunocompromised.
Diagnosis
Stool culture identifies bacterial infection and guides antibiotic choice. Blood tests assess hydration and inflammation. Colonoscopy or CT scan evaluates persistent diarrhoea.
Treatments
Oral rehydration
Replace lost fluids and electrolytes with oral rehydration salts (ORS). Water alone is not sufficient as it does not replace sodium and glucose lost with fluid.
Antibiotics
Used only for specific bacterial infections confirmed by stool culture (Campylobacter, Salmonella, C. difficile). Not appropriate for viral diarrhoea.
Loperamide
An anti-motility drug that reduces the frequency and urgency of bowel movements. Suitable for short-term use in adults when diarrhoea is inconvenient. Avoid in bloody diarrhoea or infection.
Self-care and lifestyle
- Drink clear fluids and ORS frequently in small amounts
- Eat small bland meals once appetite returns (toast, rice, banana)
- Wash hands thoroughly after using the toilet and before handling food
- Stay home from work or school until 48 hours after the last episode
Prevention
Hand hygiene is the most effective measure. Safe food preparation, refrigerating perishable foods promptly, avoiding cross-contamination, and water purification when travelling in high-risk areas.