Short answer: Diarrhoea and vomiting usually clear up on their own — vomiting usually stops within one or two days and diarrhoea within five to seven. The main risk, especially in young children, is dehydration. Give fluids in small, frequent sips; keep breastfeeding; keep formula at its usual strength; and ask a pharmacist about oral rehydration solution. Avoid fruit juice and fizzy drinks. Keep children off nursery or school until two days after the last episode. Call 111 (or your local equivalent) for signs of dehydration, and 999 for a child who is very unwell.
Your child has been sick for the fourth time, and you hardly dare give them anything in case it comes straight back up. Yet getting fluids in is exactly what matters — just in a different way than you might think.
The real risk: dehydration
Most tummy bugs are caused by viruses and pass without treatment. The danger is losing more fluid than your child takes in. Babies and young children can become dehydrated quickly.
Signs of dehydration
- fewer wet nappies, or peeing less than usual;
- dark, strong-smelling pee;
- a dry mouth and lips, or no tears when crying;
- sunken eyes, or a sunken soft spot on a baby's head;
- being unusually sleepy, floppy or irritable;
- cold hands and feet, or pale or blotchy skin.
Watch the nappies. They're the most reliable guide you have at home.
How to get fluids in
- Small sips, often. A big drink on an upset stomach tends to come back up. Try a teaspoon or a small syringe-full every few minutes, and build up gradually.
- If they're sick, wait a little and then start again with small amounts.
- Breastfeeding: keep going, offering shorter, more frequent feeds.
- Formula: keep it at its usual strength — never make it weaker. Babies on formula or solids can have small sips of water between feeds.
- Oral rehydration solution (ORS): sachets from a pharmacy that you mix with water. They replace salts and sugars in the right balance. Make them up exactly as instructed, and ask a pharmacist if they're suitable for your child.
What not to give
- Fruit juice and fizzy drinks — they can make diarrhoea worse.
- Homemade salt and sugar mixtures — getting the balance wrong can be harmful.
- Anti-diarrhoea medicines for children, unless a doctor advises them.
Food
Once your child feels like eating, offer their usual foods in small amounts. Plain, easy foods may go down best at first, but there's no need for a special diet or to stop eating.
Stopping it spreading
- Wash hands with soap and water often, especially after nappy changes and before preparing food. Alcohol hand gels don't kill some tummy bugs.
- Use separate towels, and clean toilet seats, flush handles and taps regularly.
- Keep your child off nursery or school until they haven't been sick or had diarrhoea for at least two days.
- Avoid swimming pools until at least 48 hours after symptoms stop.
When to get help
Call 111 now (or your local equivalent) if:
- a child under 5 shows signs of dehydration, such as fewer wet nappies;
- an older child still has signs of dehydration after using rehydration sachets;
- there's blood in the diarrhoea or bleeding from the bottom;
- diarrhoea lasts more than 7 days, or vomiting more than 2 days.
Call 999 (UK), 911 (US) or 112 (EU) if your child vomits blood or something that looks like coffee grounds, has green vomit, is floppy or very hard to wake, has a stiff neck, a rash that doesn't fade under a glass, severe tummy pain, or difficulty breathing. For babies, see also when to call the doctor.
Related reading
Month by month: The First Year (PDF, English) guides you through your baby's first twelve months.
Sources
- NHS — Diarrhoea and vomiting.
- NHS — Dehydration.
- NHS — When to get urgent medical help for babies and children under 5.
Written by the Bloom Guides editorial team. Last updated: 20 October 2026. General information only — not a substitute for advice from your pharmacist, GP or NHS 111.