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 6 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. Common viruses are rotavirus and adenovirus but there are many others. Because there are many viruses that cause it, a child can get gastro more than once. 

Infants younger than 15 weeks of age can have the rotavirus vaccination free of charge. This protects against one of the most common causes of gastro. 

Rarely, gastro can be caused by bacteria. This often causes blood in the poo.   

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 homes, day care, kindergartens and schools.

How long could it last?

The vomiting may settle quickly but the diarrhoea often lasts for up to 10 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 6 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. Whichever fluids your child is having, the important thing is to:

  • offer small amounts of fluid often rather than giving large amounts; aim for quarter of a cup every 15 minutes or 1 teaspoon or 5 mls in a syringe every minute
  • keep offering your child fluids even if they are vomiting 

Types of fluids 

  • 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 1 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 (which can make the diarrhoea worse):

  • cordial – make up to normal drinking strength then add 5 parts of water to 1 part of cordial
  • soup – add 5 parts of water to 1 part of soup
  • fruit juice – add 5 parts of water to 1 part of juice
  • fizzy drinks such as lemonade – add 5 parts of warm water to 1 part of drink (warm water removes the bubbles)

Your doctor or pharmacist may recommend electrolyte solutions such as Gastrolyte or Pedialyte if your child is dehydrated. You can buy these from your pharmacist - 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 your child medicines to reduce diarrhoea. They do not work and may be harmful. 

Your doctor may occasionally prescribe a medicine for vomiting. Follow the instructions given to you by your doctor. 

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 or after hours medical centre urgently if:

  • your child has vomiting and / or diarrhoea and is less than 6 months old – babies can become dehydrated and unwell quickly
  • your child is drowsy and difficult to rouse
  • your child has a lot of diarrhoea (8 to 10 watery motions in 1 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 starts vomiting green fluid (bile)
  • your child develops severe stomach pains
  • your child shows signs of dehydration (see 'How can I tell if my child is dehydrated?' above)
  • you are concerned for any other reason

You should see your doctor if:

  • your child’s diarrhoea continues for more than 10 days

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 there has been no diarrhoea for 48 hours
This page last reviewed 24 March 2015
© Paediatric Society of New Zealand and Starship Foundation 2005 – 2015
Printed on 18 April 2015. Content is regularly updated so please refer to www.kidshealth.org.nz for the most up-to-date version
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