Sudden vomiting, runny poo or both, in a child who was fine yesterday, is usually gastroenteritis: an infection of the stomach and gut, most often caused by a virus. It spreads easily through nurseries, schools and families. There is no medicine that cures it. Your job is to keep enough fluid going in until it passes, and to notice early if it isn’t.
How long it lasts
Vomiting usually stops within 1 or 2 days, and in most children within 3. Diarrhoea hangs around longer: usually 5 to 7 days, and in most children it has stopped within 2 weeks. So a child who has stopped being sick but still has loose poo on day five is following the normal course.
Get advice if the vomiting goes on for more than 2 days, or the diarrhoea for more than 7.
Who dehydrates fastest
Any child can get dehydrated, but UK guidance names the ones at higher risk:
- Babies under 1, and especially under 6 months.
- Babies who were born with a low birth weight.
- A child who has had more than 5 runny poos in the last 24 hours.
- A child who has been sick more than twice in the last 24 hours.
- A child who hasn’t been taking extra fluids, or a baby who has stopped breastfeeding while ill.
If your child is on that list, start the extra fluids early rather than waiting to see how things go.
Signs of dehydration
| In a baby | In an older child |
|---|---|
| Fewer wet nappies than usual | Peeing less often, and dark, strong-smelling pee |
| A sunken soft spot (fontanelle) on top of the head | A dry mouth, lips and tongue |
| Sunken eyes | Sunken eyes |
| Few or no tears when they cry | Thirst, headache, feeling dizzy or light-headed |
| Drowsy or irritable | Unusually tired or drowsy |
Signs as listed by the NHS. The American Academy of Pediatrics puts a number on the nappies: fewer than six wet ones a day in a baby is an early sign.
Watch the child, and count the nappies. A child who is getting more unwell, is harder to engage or unusually irritable, is peeing less, or has pale or mottled skin and cold hands and feet is showing the signs UK guidance tells parents to act on. Wet nappies coming about as often as usual, and a child who still wants to play, are good signs.
Keeping fluids going at home
- Little and often. A big drink on an upset stomach tends to come straight back. Offer small amounts every few minutes, from a cup, bottle, spoon or syringe, and keep going after each vomit. Sips add up.
- Keep breastfeeding or bottle feeding. If your baby is being sick, give smaller feeds more often. Make formula at its usual strength; never water it down. Babies on formula or solid food can have small sips of extra water between feeds, boiled and cooled first if they are under 6 months.
- Oral rehydration solution. These sachets, mixed with water, put back the sugar and salts lost in vomit and poo, which plain water doesn’t. A pharmacist can recommend one for your child’s age. Make it up exactly as the pack says. It’s worth having ready for a child in the higher-risk group above, and a doctor may tell you how much to give after each watery poo.
- Go easy on sugary drinks. UK guidance says not to give young children fruit juice or fizzy drinks, which can make diarrhoea and vomiting worse. Guidance in Australia and the US does allow half-strength apple juice for an older child who won’t drink anything else, and warns against lemonade, sports drinks and other sugary drinks at full strength.
- Food when they want it. There is no special diet. Children can have their usual food once they feel like eating, and a child who is drinking well but not eating for a day or two is fine. If a doctor is treating your child for dehydration, follow what they say about food until they are rehydrated.
Medicines
- No anti-diarrhoea medicine under 12. Loperamide and similar are not suitable for younger children, and over-the-counter medicines to stop vomiting or diarrhoea can be harmful for them. A doctor can prescribe an anti-sickness medicine if vomiting is severe.
- Paracetamol for discomfort is fine. Check the leaflet for your child’s age and dose.
- Antibiotics are not usually needed. Most tummy bugs are viral, and antibiotics do nothing for a virus.
Never give aspirin to anyone under 16. Check the label of anything you did not buy specifically for children.
Red flags: get help now
Call your emergency number or go straight to an emergency department if your child:
- Has blue, grey, pale or blotchy skin, lips or tongue, or their skin feels cold. On brown or black skin this can be easier to see on the palms and soles.
- Is confused, very sleepy or hard to wake, or not responding as usual.
- Has difficulty breathing, or is taking lots of quick breaths.
- Has green or yellow-green vomit.
- Is vomiting blood, or vomit that looks like ground coffee.
- Has a sudden, severe tummy ache.
- Has a stiff neck and pain looking at bright lights, or a sudden, severe headache.
- May have swallowed something poisonous.
Get medical advice the same day (in the UK, your GP or NHS 111) if:
- You are worried about a baby under 12 months.
- Your baby has stopped breastfeeding or bottle feeding.
- Your child shows any of the signs of dehydration above, or still does after oral rehydration solution.
- They keep being sick and can’t keep fluids down.
- There is blood in the poo, or bleeding from the bottom.
- Vomiting has lasted more than 2 days, or diarrhoea more than 7.
- They have constant, severe tummy pain that paracetamol doesn’t help.
- They also have a fever: 38°C or above under 3 months, or 39°C or above from 3 months. See our fever guide.
- They became ill after travelling abroad.
- You are worried. That is reason enough to ask.
Stopping it spreading
Washing hands with soap and warm water, and drying them properly, is the single most important thing. Do it after every nappy change or trip to the toilet, and before preparing or eating food. Don’t share towels. Wash anything with vomit or poo on it separately on a hot wash, and wipe toilet seats, flush handles, taps and door handles every day while someone is ill.
Keep your child home from nursery or school until 48 hours after the last vomit or runny poo, and keep them out of swimming pools for 2 weeks after the last diarrhoea.
Common questions
How long does a stomach bug last in a child?
Vomiting usually stops within 1 or 2 days, and in most children within 3. Diarrhoea usually lasts 5 to 7 days, and in most children it stops within 2 weeks. Get advice if vomiting goes on for more than 2 days or diarrhoea for more than 7.
Can I give my child medicine to stop diarrhoea?
Not under 12. Anti-diarrhoea medicines such as loperamide are not suitable for younger children. Paracetamol is fine for discomfort if you follow the leaflet. Never give aspirin to anyone under 16.
When can my child go back to nursery or school?
When they have not been sick or had diarrhoea for at least 48 hours. UK and Australian children’s guidance also says no swimming pools for 2 weeks after the last episode of diarrhoea.
Should I water down formula when my baby has diarrhoea?
No. Keep making formula at its usual strength, and keep breastfeeding as normal. If your baby is being sick, give smaller feeds more often. Babies on formula or solid food can have small sips of extra water between feeds, boiled and cooled if they are under 6 months.
Doodlebug keeps count while you’re busy
Log each vomit and runny poo as a symptom, each nappy with how wet it was, and each feed, in two taps. When you ring for advice and they ask how many wet nappies since this morning, the answer is on one timeline instead of in your head. It’s free on the App Store.
Get DoodlebugSources
- NHS, Diarrhoea and vomiting.
- NHS, Dehydration.
- National Institute for Health and Care Excellence, Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management (CG84).
- The Royal Children’s Hospital Melbourne, Gastroenteritis (gastro).
- American Academy of Pediatrics, Signs of Dehydration in Infants & Children.
- American Academy of Pediatrics, Drinks to Prevent Dehydration When Your Child is Vomiting.
Doodlebug is a tracking app, not a medical service. This page is general information drawn from published guidance and is not advice about your child. Doses, age limits and the name of your emergency number vary by country: follow the pack and your own doctor. If you are worried about your child, get medical help.