What is norovirus?

Norovirus is a virus that causes gastroenteritis ('gastro') — inflammation of the stomach and intestines.

It is sometimes known as 'winter vomiting', as it is more common in colder weather. Norovirus is one of the main causes of stomach and intestinal illness worldwide.

Norovirus is also sometimes referred to as 'gastrointestinal flu' (gastro flu).

What are the symptoms of norovirus?

If you have norovirus, you may develop symptoms soon after being exposed, usually within 1 to 2 days. Common symptoms include:

• nausea and vomiting
• watery diarrhoea
• crampy stomach pain
• slight fever
• muscle aches
• feeling tired and unwell

Most people recover quickly and symptoms resolve within 1 to 3 days.

Severe symptoms

Symptoms can be more severe and longer-lasting in some groups of people, such as:

• older adults
• young children
• people with a weakened immune system

Severe symptoms may include:

• high fever
• seizures in children and newborn babies
• frequent vomiting
• bloody diarrhoea
• severe abdominal (tummy) pain

If you or someone you care for has a severe gastroenteritis infection, seek medical or hospital care.

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What causes norovirus?

Norovirus is caused by a virus that affects the stomach and intestines. It is highly contagious. This means it spreads easily from person to person.

Person to person spread

Norovirus usually spreads through contact with the poo of an infected person. It can also spread through contaminated air droplets. This means you can get it by touching contaminated surfaces or through direct contact with an infected person, for example if you:

• touch their vomit or faeces (poo)
• touch their unwashed hands
• breathe in virus particles that are in the air after they vomit
• eat food or drink water that has been contaminated by them

The virus can live on surfaces touched by the infected person, such as:

• handrails
• doorknobs
• chair arms

Crowded places

Norovirus often causes gastro outbreaks in places where a lot of people live, work or spend time together. These include:

• aged care facilities
• childcare centres
• schools
• cruise ships
• restaurants

When should I see my doctor?

You should see your doctor if:

• your diarrhoea lasts for more than a few days
• you are vomiting for more than a few days
• you haven't been able to drink any fluids for several hours

When should I seek urgent care?

Seek urgent care if you have severe symptoms. Also, see your doctor urgently if you have a young child, you are an older adult or have a weakened immune system and:

• you or your child has any severe symptoms
• you or your child are unable to keep any fluids down
• you or your child have signs of dehydration, such as thirst, feeling drowsy or weeing less than usual

Your child may be dehydrated if they have severe or ongoing diarrhoea. Read more on diarrhoea in babies and children.

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How is norovirus diagnosed?

Norovirus infection is usually diagnosed based on your symptoms. Your doctor may suspect norovirus if you suddenly experience vomiting and watery diarrhoea, especially in the winter months.

To confirm the diagnosis, your doctor may ask you for a stool (poo) sample for testing in a laboratory. This may be needed if:

• your symptoms are severe or last a long time
• you have a weakened immune system
• the diagnosis is needed to help check and manage a norovirus outbreak

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How is norovirus treated?

Norovirus usually gets better on its own. There are steps you can take to feel better and avoid complications. In some cases, your doctor may recommend medicines to help relieve your symptoms.

Self-care at home

It is important to stay hydrated to avoid dehydration.

• Drink plenty of fluids to replace fluids lost through vomiting and diarrhoea.
• Sip small amounts every 15 to 30 minutes and gradually drink more as you feel better.
• Choose fluids with some salt, such as oral rehydration solutions or broth.
• Avoid sugary drinks, such as juice or soda, and stay away from alcohol.

When you are ready to eat, choose lean meats, fruits, vegetables and whole grains. Avoid fatty or sugary foods as they can make your symptoms worse.

Medicines

There is no medicine or antibiotic available to treat norovirus. Only use antiemetics (anti-vomiting) or anti-diarrhoeal medicines if your doctor has told you to use them.

If you are living with diabetes, make sure to monitor your blood sugar levels more often. Ask your doctor for advice if needed.

Other treatment options

Severe dehydration may require hospital treatment. Treatment may include receiving fluids directly into a vein via an intravenous (IV) line ('drip').

What are the complications of norovirus?

Norovirus is usually mild, but it can sometimes lead to complications, especially in children.

Some children with norovirus may have seizures. In rare situations, norovirus can lead to brain swelling (encephalitis) in children.

How is norovirus prevented?

Norovirus is easily spread to other people. Preventing norovirus involves good hygiene, cleaning practices and staying away from others when you are sick. There is no vaccine to prevent norovirus.

To help prevent infection:

• Wash your hands with soap and running water after using the toilet or changing nappies.
• Wash your hands with soap and water before eating or handling food.
• Alcohol-based hand sanitisers do not kill norovirus, so use soap and water.
• Wipe down household surfaces and disinfect with a diluted bleach-based cleaner.
• Wear gloves, a mask and a gown when cleaning areas contaminated by vomit or diarrhoea.
• Avoid preparing food for others for at least 2 days after your symptoms stop.
• Healthcare workers should stay home for 48 to 72 hours after their symptoms stop.

Resources and support

• NSW Health has a norovirus fact sheet.
• Communicable Diseases Network Australia provides guidelines for the public health management of norovirus outbreaks in Australia.
• NSW Government Food Authority offers a video and information about food poisoning.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

Other languages

• Multicultural Health Communication Service provides translated information about viral gastroenteritis.
• HealthTranslations Victoria offers translated information on gastroenteritis.
• The Food Safety Information Council provides translated videos on food safety.

Looking for information for Aboriginal and/or Torres Strait Islander people?

• HealthInfoNet provides a research article about the associations between housing and gastrointestinal infection in Aboriginal children.
• The Food Safety Information Council has information on food safety for Aboriginal and/or Torres Strait Islander people.