Diarrhoea: When to Worry & UK Online Doctor
Educational information — not medical advice.
This article was prepared by the OnlineDoctor24 editorial team and reviewed for factual accuracy against UK clinical guidance (NHS and NICE). It is not written by a doctor and does not replace personal medical advice. For symptoms specific to you, book an online doctor consultation.
Key points
- Most acute diarrhoea is viral and clears in 2–3 days.
- Hydration is the priority — sipping fluids throughout the day.
- Loperamide can help adults but should be avoided if there's blood or fever.
- Antibiotics are rarely needed.
- Persistent symptoms beyond a week warrant medical review.
Self-care
- Sip clear fluids throughout the day.
- Oral rehydration sachets if losing lots of fluid.
- Eat small, plain meals when able.
- Stay home and avoid food preparation for others.
Medication
- Loperamide 4 mg, then 2 mg after each loose stool (max 16 mg/day adults). Avoid if blood, fever or under 12.
- Antibiotics only for specific bacterial causes — usually after stool culture.
Red flags — when to seek urgent help
Call 999 or go to A&E if you experience any of the following:
- Blood in stool
- High fever
- Severe dehydration (dizziness, dry mouth, no urine)
- Severe abdominal pain
- Symptoms lasting more than a week
- Recent travel to high-risk areas
Frequently asked questions
Common questions UK patients ask about acute diarrhoea.
How an online doctor can help
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This article is for general information only and does not replace personal medical advice from a qualified doctor. Content is reviewed against UK NHS and NICE guidance by the OnlineDoctor24 editorial team and is not authored by a medical doctor. If your symptoms worsen or you are unsure, please book a consultation with a GMC-registered GP.
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