Gastroenteritis in children

Gastroenteritis is a gut infection that causes stomach cramps, vomiting and diarrhoea (runny, watery poos). Children with vomiting and diarrhoea need to drink lots of fluids to prevent them from becoming dehydrated.

Gastroenteritis is also known as gastro, tummy bug, food poisoning, traveller's diarrhoea, stomach flu or viral enteritis.

Common causes of gastro in children are viruses, bacteria (food poisoning) and intestinal parasites. Read more about causes of gastro in children.

Most children with gastro have mild symptoms that do not need to be treated by a doctor. Sometimes gastro can lead to severe dehydration and other dangerous complications. This is more likely to happen in babies, children with chronic illnesses and children with a weakened immune system.

When to see a doctor

  • If your baby is under 6 months old and has diarrhoea and vomiting, see a doctor straight away. Babies can become dehydrated and unwell quickly.
  • If your child is older than 6 months and has diarrhoea and vomiting, see your doctor if they have any of the following:
    • Poo that contains blood.
    • Poo that smells really bad. 
    • Signs of dehydration such as dry mouth and tongue, sunken eyes, cold hands and feet, unusual sleepiness or lack of energy, dry nappies, not passing as much urine as usual or passing a small amount of dark yellow urine.
    • Blood or bile (greenish fluid) in the vomit.
    • Severe tummy pain or a swollen tummy.
    • Skin colour and whites of the eyes turn yellow.
    • Recent travel to a developing country or to any area where sanitation is poor.
    • Vomiting or diarrhoea that continues for more than 10 days.

What are the symptoms of gastro?

Symptoms include:

  • diarrhoea (runny, watery poos)
  • pain or cramps in the abdomen, tummy or puku
  • vomiting 
  • irritability
  • poor appetite
  • mild fever
  • headache.

Treatment for babies and children with gastro


Any baby under 6 months old with diarrhoea and vomiting should be seen by a doctor straight away. Babies can be dehydrated and unwell quickly. Read more about caring for a baby with gastro.


In most children, gastro will settle on its own after a few days. You can look after your child at home.

The main aim is to prevent dehydration caused by fluid loss due to vomiting and diarrhoea. Encourage them to drink plenty of fluids – offer small amounts of fluid often rather than giving large amounts. Water is best but diluted juice, cordial or watery soup may also be given.

If your child is being breastfed, carry on breastfeeding. You may need to feed them more often and drink extra liquid yourself. If you are bottle feeding, continue to do so. Don’t dilute baby formula, use it as usual.

Let your child eat if they're hungry, even if vomiting and diarrhoea continues. Continuing to feed your child can help to speed up recovery.

Make sure your child gets plenty of rest and keep them away from school or pre-school until at least 48 hours after their symptoms have cleared.

Read more about caring for a child with gastro – including w
hich fluids, foods and medications are suitable.

How to prevent gastro?

Gastro can be easily passed from person to person. If your child has gastro, keeping them off school or pre-school for at least 48 hours after the last episode of diarrhoea or vomiting.

Washing hands regularly and properly is one of the best ways to reduce the chance of getting gastro and spreading it.

Always keep meat refrigerated, cook meat thoroughly and wash fruit and vegetables.

Read more about preventing gastro.

Learn more

Gastroenteritis Kidshealth, NZ
Rotavirus Immunisation Advisory Centre


Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management NICE guideline April 2009
Gastroenteritis starship clinical guidelines Starship, NZ, 2017
Assessment and management of infectious gastroenteritis BPAC NZ, 2009

Credits: Health Navigator Editorial Team. Reviewed By: Nir Fireman, Auckland DHB Last reviewed: 05 May 2017