Diarrhoea: what to do and when to worry
Most diarrhoea clears up within a few days. The priority is replacing lost fluid — and knowing the signs that need a doctor.
Stay hydrated
Watery stool takes water and salts with it. Sip fluids little and often. Oral rehydration sachets from a pharmacy replace salts and sugars in the right balance — especially useful for older adults or anyone with other health conditions.
Signs of dehydration
- Dark, strong-smelling pee, or peeing less
- Dizziness or light-headedness
- Dry mouth, lips and eyes
- Feeling very tired
Eat when you feel able
There’s no need to starve yourself. Plain foods are often easiest. Ease off caffeine, alcohol, spicy and very fatty food until things settle.
Stop it spreading
Wash hands with soap and water, don’t share towels, and stay off work or school until 48 hours after the last episode if it may be infectious.
Get medical help if
- It lasts more than 7 days, or keeps coming back
- There’s blood in your poo, or black stool
- You have signs of dehydration that don’t improve, or a high temperature
- You have severe tummy pain
Call NHS 111 or your GP; call 999 for heavy bleeding, collapse or very severe pain. Frequent loose stools lasting weeks is also a change in bowel habit worth discussing with your GP — see red-flag symptoms.
Frequently asked questions
How long does diarrhoea normally last?
Usually a few days and often under a week. See a GP or call NHS 111 if it lasts more than 7 days, or if you see blood or have signs of dehydration.
Sources
This guide is for general education and is not a substitute for advice from your doctor. If you are worried about symptoms, contact your GP or NHS 111.