Gastroenteritis is a broad term used to describe infections of the gut that cause diarrhoea and vomiting.
Clinically reviewed by:
Dr Mataroria Lyndon on 28.6.2022


Also known as: Pokenga whēkau, Gastro, Intestinal flu, Viral enteritis, Stomach/tummy bug, Food poisoning, Traveller’s diarrhoea

  • Gastroenteritis is a broad term used to describe infections of the gut that cause diarrhoea and vomiting. It is most commonly caused by viruses, but can be caused by bacteria and amoebas.
  • The cause of gastroenteritis varies, but it is commonly caught through not washing your hands, or through contaminated food or water.
  • Almost all New Zealanders will experience gastroenteritis at some point in their lifetime.
  • Most people recover after a few days. Resting and staying hydrated is often all that’s required.
  • Occasionally gastroenteritis can make you very unwell - due to decreased water intake and losses by vomiting and diarrhoea - leading to dehydration. This is particularly dangerous in young children and infants.
  • Dehydration (see below), high fevers, or blood in the diarrhoea are all signs that gastroenteritis may be more serious and should be reviewed by a medical professional. This is especially important in young children or infants.

Need help?

If your child is aged 6 months or younger and is vomiting or has diarrhoea, take them to a doctor immediately as dehydration is a real danger in infants.

What causes gastroenteritis?

  • Usually gastroenteritis is transmitted ‘hand to mouth’ which is why washing your hands is so important before eating and after using the toilet. It can also be transmitted through contaminated food or water.
  • Gastroenteritis is commonly caused by a virus that is passed from one person to another.
  • Bacteria that cause gastroenteritis can also grow in food that hasn’t been cooked properly, or isn’t fresh.
  • Contaminated water can also carry bacteria or viruses that cause gastroenteritis - this is a very common cause of ‘traveller’s diarrhoea’ when travelling to countries with low quality water supply.


In Adults
  • Nausea or vomiting
  • Diarrhoea
  • Stomach cramps
  • Fatigue
  • Weakness
  • Loss of appetite
  • Headaches
  • Fever
  • Chills
In Children

Symptoms in children are much the same as in adults, however younger children are more likely to become dehydrated.

Keep an eye out for these signs:

  • Dry mouth
  • Less wet nappies than usual
  • Dark yellow urine
  • Sunken eyes
  • Lethargy / floppiness
  • Blood in diarrhoea

If you notice any of these signs, or are just worried your child is getting worse, get them reviewed by a doctor.


For Adults

  • Stay hydrated – the best way to do this is to drink small sips of water often.
  • Electrolyte drinks and oral rehydration salts can also help and can be purchased over-the-counter at a pharmacy.
  • Stay away from alcohol, tea and coffee.
  • Avoid food and drinks that are high in fat, oil or sugar.
  • Take it easy and get some rest.
  • Prevent the bug spreading by carefully washing your hands before handling food, or after going to the toilet, and staying home until you’re clear of symptoms for at least 24 hours
For Children
  • Like adults, the best thing you can do for a child is keep them hydrated. Water is usually effective, but in more severe cases you can give them oral rehydration solution.

    It’s best not to give them a big cup or liquid, as drinking too quickly can bring on more vomiting. Instead, give them a small amounts, more often.
  • If they’re hungry, let them eat, but stick to plain foods.. Appetite is a good sign, and eating can help them to recover faster.
  • Ensure your child rests and keep them at home until they have no symptoms for 24 hours.
  • Some medicines can stop or decrease vomiting and/or diarrhoea, but these aren’t always a good idea, and we recommend speaking to a doctor or pharmacist before taking anything.
  • Oral rehydration salts or electrolyte drinks can help you stay hydrated more effectively than plain water.
Proactive protection
  • Good hand hygiene is key to protecting yourself against gastroenteritis. Wash your hands often with soap and warm water. This is particularly important before and after handling food, and after going to the toilet.

Good food hygiene is also really important:

  • Don’t eat food that has passed its expiration date.
  • If it smells or looks funny, throw it out.
  • Wash anything that has been used to prepare meat, poultry and seafood with hot soapy water.
  • Spray surfaces that have been in contact with uncooked meat, poultry and seafood with cleaning spray before wiping them down.
  • Keep fresh food in the fridge and ensure meat, poultry and seafood are kept separate from everything else.
  • Make sure frozen food is wrapped properly and eaten within 6 months.
  • Don’t defrost food on your kitchen bench, instead let it defrost in the fridge or in the microwave.
  • Cook chicken thoroughly.
  • Only reheat leftovers once, and ensure they’re extremely hot.

If you’re travelling, it pays to do your research. In some places, water isn’t safe to drink, so you have to buy bottled water or water purification tablets. You should also be wary of ice, or anything that has been washed in water like salad or fruit.

Should I see a doctor?

You should see a doctor if you:

  • Find blood or pus in your poo
  • Are passing no or very little urine
  • Have a very dry tongue
  • Feel extremely weak and lethargic
  • Have high fevers
  • Have severe tummy pains
  • You should also see a doctor if any of your symptoms last longer than a week.

If your child is aged 6 months or younger and is vomiting or has diarrhoea, take them to a doctor immediately as dehydration is a real danger in infants.

If your kid is older than 6 months, you should take them to a doctor if they have:

  • Blood in their poo
  • High fevers
  • Any signs of dehydration
  • Dehydration is common in people with gastroenteritis – especially children and eldery people.

Moderate to severe dehydration often requires medical assistance. Some people will be given electrolyte solutions to drink. In more extreme cases, they may need an intravenous drip or a nasogastric tube to increase their fluids.

Which specialist should I visit?


How long does gastroenteritis last?

Most people will recover within a few days – this goes for both children and adults.