Viral gastroenteritis (gastro)

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Key points to remember

  • gastro (gastroenteritis) is a bowel infection causing diarrhoea, and sometimes vomiting
  • diarrhoea means runny, watery poo
  • children need to drink plenty of fluids if they have gastro
  • give small amounts of fluid often
  • gastro can cause dehydration, especially in babies and young children
  • watch for signs of dehydration (such as dry lips, fewer wet nappies, sunken eyes, unusual sleepiness) and take your child to see a doctor urgently if you suspect it
  • if your baby is less than six months old and has vomiting and / or diarrhoea you should see a doctor urgently - babies can become dehydrated and unwell quickly

What is it?

Gastro (gastroenteritis) is a bowel infection which causes diarrhoea (runny, watery poo) and sometimes vomiting.

What causes it?

Gastro is usually caused by a virus.

For information about non-viral causes of gastro, see the Ministry of Health pamphlets on:

How do people get the virus?

A child can catch the virus when they:

  • touch something which has been in contact with the diarrhoea or vomit of a person with the infection, and
  • they put their hand in their mouth

The virus is easily spread in day care, kindergartens and schools.

How long could it last?

The vomiting may settle quickly but the diarrhoea often lasts for up to ten days. This doesn’t matter as long as your child is drinking well and seems to be improving in themselves.

What puts my child at risk of getting it?

Gastro affects all age groups, but is more common, and can be worse in babies and young children.

What are the signs and symptoms?

The most common symptoms are:

  • feeling sick (nausea)
  • diarrhoea (runny, watery poo)
  • vomiting

Sometimes a child with gastro will have:

  • a fever
  • tummy pains

How can I care for my child at home?

If your child is over six months old and has mild gastro and is not dehydrated, you can care for them at home. The main treatment is to keep giving your child fluids:

  • small amounts of fluid often is better than giving large amounts; aim for quarter of a cup every 15 minutes or five mls on a teaspoon or in a syringe every minute
  • keep offering your child fluids even if they are vomiting

Which drinks should I give my child?

  • if you are breastfeeding, continue to feed on demand; you may need to increase the frequency of feeds and give extra fluid
  • if your child is on formula, continue to give them formula feeds
  • if your child is over one year, you may give them cow’s milk

You may also give your child the following drinks as long as your child is not dehydrated – the drinks must be diluted with water as they contain too much sugar:

  • cordial – make up to normal drinking strength then dilute one part with five parts water
  • soup – add five cups of water to one cup of soup
  • fruit juice – add five cups of water to one cup of juice
  • fizzy drinks such as lemonade – add five cups warm water to one cup of drink (warm water removes the bubbles)

You can give your child electrolyte solutions such as Gastrolyte or Pedialyte if they are dehydrated; you can buy these from your chemist - prepare them according to the instructions on the packet.

What drinks shouldn’t I give my child?

Do not give infants or children with diarrhoea:

  • undiluted soft drinks, fruit juices, Lucozade, Ribena, sports drinks (such as Powerade or Gatorade) – these contain too much sugar and can make your child’s diarrhoea worse
  • coffee and tea – these can make your child become dehydrated

Should I continue to give my child their normal food?

  • children should be offered food if they are hungry, even if diarrhoea continues; continuing to feed your child can speed up recovery and can reduce the length of time your child has diarrhoea
  • your child may refuse food at first – this is not a problem as long as fluids are taken
  • if possible do not stop food for more than 24 hours
  • starchy simple foods are best – try and offer foods such as bread or toast, porridge, rice, potatoes, plain biscuits, yoghurt, milk pudding

What foods should I avoid?

Do not give your child fatty or sugary foods such as:

  • takeaways
  • chippies, sweets, cakes, chocolate, ice cream, cream, coconut cream

Will my child need any medicines?

Do not give medicines to reduce your child’s vomiting or diarrhoea. They do not work and may be harmful or make the diarrhoea worse.

Viral gastro can not be treated with antibiotics. The body will clear out the virus on its own without treatment.

What can I do for my baby’s sore bottom?

Diarrhoea can cause a rash; after each bowel motion wash and dry your child’s bottom well and then apply a protective cream or ointment (such as zinc and castor oil cream or Vaseline).

How can I tell if my child is dehydrated?

Dehydration is the loss of fluid, due to vomiting and diarrhoea. The younger the child, the easier it is for them to become dehydrated.

Watch for signs of dehydration:

  • dry mouth and tongue
  • sunken eyes
  • cold hands and feet
  • unusual sleepiness or lack of energy
  • fewer wet nappies or not passing as much urine as usual

If your child has any of these signs, you need to take them to see a doctor urgently.

When should I seek help?

You should see your doctor if:

  • your child’s diarrhoea continues for more than ten days

You should see your doctor or after hours medical centre urgently if:

  • your child has vomiting and / or diarrhoea and is less than six months old – babies can become dehydrated and unwell quickly
  • your child is drowsy and difficult to rouse
  • your child has a lot of diarrhoea (eight to ten watery motions per day)
  • there is blood or mucus in your child’s poo
  • vomiting is increasing or your child is unable to keep fluids down
  • your child develops severe stomach pains
  • your child shows signs of dehydration (see How can I tell if my child is dehydrated?)
  • you are concerned for any other reason

Dial 111 within New Zealand for urgent medical help (use the appropriate emergency number in other countries) if you are very concerned about your child.

How can I help prevent the spread of gastroenteritis?

Gastro spreads very easily to others. You can help prevent spreading the disease by:

  • thorough handwashing – especially after going to the toilet, after nappy changing and before handling food; encourage your child to wash and dry their hands after using the toilet
  • thorough cleaning of your toilet and bathroom areas
  • washing dirty clothing, in hot water preferably, and rinsing separately from the rest of the family laundry
  • avoiding sharing food and drinks
  • keeping your child away from friends and other children until vomiting and diarrhoea have stopped; children with diarrhoea must stay away from daycare, kindergarten and school until the diarrhoea has stopped
This page last reviewed 02 April 2013
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Printed on 07 March 2015. Content is regularly updated so please refer to for the most up-to-date version
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