Gastroenteritis (tummy bug) gives you diarrhoea and vomiting, and is usually caused by viral or bacterial infections.

The main symptoms of gastroenteritis are frequent diarrhoea or vomiting or both. These symptoms have different causes, but are usually viral or bacterial infections. With gastroenteritis, your stomach and intestines become irritated and inflamed.

The most common causes of viral gastroenteritis are norovirus and rotavirus. Campylobacter, E. coli, and salmonella are common causes of bacterial gastroenteritis. Parasitic gastroenteritis is usually caused by giardia or cryptosporidium organisms.

Infants and young children, older people, and people with a weakened immune system are most at risk of getting a severe bout of gastroenteritis.

The illnesses below can all result in gastroenteritis. You can find out more about their causes and treatments on this website:

If you are concerned about gastroenteritis, call Healthline on 0800 611 116 or see your doctor or practice nurse.

Viral gastroenteritis is highly infectious, and large numbers of people can be affected in a short amount of time. It spreads very easily from person to person, by contact with the vomit or faeces (poo) of an infected person. This could be from shaking hands with someone who has been sick and has the virus on their hands, or from contaminated (unsafe) objects like door handles and cutlery, and food and drink.

People usually get bacterial gastroenteritis by eating or drinking food or water that is contaminated with the bacteria. Bacterial gastroenteritis is less easily passed from person to person, but large numbers of people may become affected from contaminated food or water.

The main symptoms are diarrhoea and vomiting, but you might also have stomach pain, cramping, fever, nausea, loss of appetite, and a headache.

Depending on the cause, symptoms may appear within a few hours to a couple of weeks after infection. The illness can range from mild to severe. Symptoms usually last one or two days, but can occasionally last for up to 10 days.

Diarrhoea and vomiting can easily cause dehydration - meaning your body doesn’t have enough fluid to function properly. Signs of dehydration include dry skin/dry mouth, feeling lightheaded, and being really thirsty. Make sure you drink plenty of fluids if you experience these symptoms.

Most people with gastroenteritis recover within a few days without needing medical treatment, as long as they don’t become dehydrated. To prevent dehydration, drink plenty of water and other fluids. Clear fluids, such as water and diluted cordials are best. Ice blocks are a good way of getting fluids into children.

Some people with severe gastroenteritis caused by bacteria may be given antibiotics. Only the symptoms can be treated with viral gastroenteritis.

If you are concerned, call Healthline on 0800 611 116 or see your doctor or practice nurse.

Keep children with gastroenteritis out of day care and school until at least 48 hours after their symptoms have gone. Adults should stay away from work for 48 hours after their symptoms have gone.

To reduce the risk of spreading acute gastroenteritis, wash and dry your hands thoroughly, especially before eating or preparing food, and after going to the toilet, changing nappies, or after contact with an infected person.

Auckland Regional Public Health Service is notified of acute gastroenteritis in some cases – for example, where there is a known causative organism, suspected common source, or where the person is in a high-risk occupation, such as a food handler or an early childcare worker. We can then monitor the number of people who have the disease and give health professionals advice on how to reduce its spread in the community.


There are specific requirements for notifiable diseases in the Auckland region.

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Last updated 26.2.2021

For health advice call Healthline for free anytime on 0800 611 116
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