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Flu (influenza)

Key facts

  • Influenza (the flu) is a viral infection that causes fever and chills, sneezing, coughing and a sore throat.
  • The flu can be serious for some people, but if you are otherwise fit and healthy you usually do not need to see a doctor.
  • The best way to prevent the flu is to have a flu vaccination every year.
  • Influenza can be diagnosed with a PCR test or a rapid antigen test (RAT).
  • You can treat the symptoms of mild flu by resting and drinking plenty of water.

What is the flu?

Influenza (the flu) is a very contagious viral infection. It is a respiratory (relating to breathing) illness that can affect your nose, throat and sometimes your lungs.

There are 2 main types of influenza viruses:

  • influenza type A
  • influenza type B

There are also many subtypes and strains.

The virus that causes COVID-19 is different from the virus that causes influenza.

Influenza infections are more serious than the common cold. They can cause major outbreaks and severe disease.

The flu is the most common vaccine-preventable disease in Australia.

Is it the cold or flu? infographic promotional tile

See this comparison of cold and flu symptoms.

The flu is also different from illness caused by human parainfluenza viruses (HPIVs).

While the flu affects people of all ages, HPIVs more commonly affect children. HPIVs can also cause mild to severe illnesses.

Some strains of the influenza virus can also infect other animals. Animal influenza viruses are different from human seasonal influenza viruses and do not easily pass between people and animals. If you want health advice on bird flu (avian influenza), read the healthdirect bird flu blog.

When is the flu season?

Influenza infections are generally most common during the winter months, from June to September. There is often more than one strain of influenza in the community at that time.

You should get your annual flu vaccine any time from April, before the flu season begins. Each year the vaccine is made to match the most common strains of flu.

What are the symptoms of the flu?

The symptoms of the flu may include:

Sometimes you may also have:

These symptoms are more common in children with the flu.

It is possible to get the flu even if you have been vaccinated. This may be due to your illness being caused by a flu strain not covered by the year's vaccine.

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What causes the flu?

There are 4 types of influenza viruses:

  1. influenza A virus
  2. influenza B virus
  3. influenza C virus
  4. influenza D virus

Influenza types A and B are usually the cause of seasonal flu.

How is influenza spread?

Influenza is spread through:

  • breathing in virus droplets that stay in the air after a person with the flu coughs or sneezes
  • touching surfaces contaminated with the virus droplets and then touching your mouth or nose

When should I see my doctor?

Warning:

If your baby is younger than 3 months old and has the flu and a fever above 38°C, take them to the nearest hospital emergency department immediately, or call triple zero (000) and ask for an ambulance.

You should see your doctor if:

  • your symptoms are getting worse
  • you are experiencing shortness of breath or difficulty breathing
  • you have symptoms of possible dehydration — dizziness when you stand up, passing less urine (wee) than usual
  • you are vomiting so much you cannot keep any liquids down
  • you are confused

If you have the flu, you should wear a mask to your medical appointment to help lower the spread of viruses to other people.

When should I visit an urgent care clinic?

If you need to see your doctor but cannot wait for an appointment, you may be able to get treatment at a Medicare Urgent Care Clinic. Use the Service Finder to find your nearest one.

When should I call an ambulance or go to an emergency department?

You should call for an ambulance or go to an emergency department if you are having trouble breathing.

You should call an ambulance or go to an emergency department if your child has the flu and:

  • has a fever and is less than 3 months old
  • is having trouble breathing
  • can't stop vomiting, isn't drinking or feeding
  • is difficult to wake up — they seem floppy, sleepy and are less responsive
  • cannot be comforted
  • is not passing urine (wee) — has not had a wet nappy for a few hours
  • their skin has a rash that does not fade when you press on it, or is blue or grey

If your child has any of these symptoms, or if you feel worried, you should call an ambulance or go to an emergency department. See Fever in children and Symptoms of serious illness in babies and children for more information.

If you have mild symptoms and are otherwise fit and healthy, there is usually no need to see a doctor.

Am I in a high-risk group for influenza?

You are more likely to get very sick and have complications from influenza if you are:

You may also be at risk of a severe influenza infection if you are living with any of these illnesses:

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How is the flu diagnosed?

During the flu season, your doctor can diagnose you with the flu by checking your symptoms and examining you.

Sometimes, your doctor may want to confirm a diagnosis of influenza and will arrange a flu test.

This involves taking a sample of cells and mucus from your nose or throat using a sterile cotton swab. This sample is then sent to a pathology laboratory for testing.

Your doctor may also test you for COVID-19.

Can I diagnose influenza at home?

You can test for the flu at home using a rapid antigen self-test (RAT) (Opens in new tab). These are like the ones used to test for COVID-19.

Some RATs can test for multiple viruses, like:

How is the flu treated?

Treatment for the flu can include self-care at home, over-the-counter or prescription medicines.

Most people get better by themselves without needing any specific treatment.

Self-care at home

Some things you can do to ease your flu symptoms are:

Medicines to manage the flu

To manage your flu symptoms, you can take:

Antiviral treatments

Your doctor may prescribe you antiviral medicines if you:

  • have been admitted to hospital to manage your symptoms
  • are pregnant or up to 2 weeks postpartum
  • are at a higher risk of severe illness or complications from influenza

Not everybody with the flu will be prescribed antivirals. Together with your doctor, you can discuss if you need them and if they will help your recovery.

Antiviral medicines help to shorten the length of your illness and reduce your risk of complications.

Antiviral treatments are most effective when given within 48 hours of you getting symptoms.

Antibiotics

Antibiotics are not generally used to treat flu. This is because antibiotics do not work for viral infections. If your doctor gives you antibiotics, it may be because you developed a bacterial infection as a complication of your flu.

Read more about medicines for colds, flu and COVID-19.

Should I stay at home?

If you are sick with the flu, stay home and avoid close contact with other people until you feel better.

If your child has the flu, keep them at home until they are free from symptoms.

Should I keep my child home from school?

If your child has an infectious condition, you may need to keep them home from day care or school to stop it from spreading.

Read the list of common childhood illnesses, including colds and flu, and their recommended exclusion periods.

What are the complications of the flu?

Influenza infections can lead to serious complications, such as:

These complications are most likely in people at higher risk of severe illness.

Can the flu be prevented?

The best way to prevent the flu is to have a flu vaccination every year.

Flu vaccine

Influenza vaccines protect against different types of influenza A and influenza B.

There are different types of influenza vaccines. Speak with your doctor about the best vaccine for you.

You should get your annual influenza vaccine before the flu season begins. This will help protect you for the peak flu season. You get the highest level of protection in the first 3 to 4 months after vaccination.

You can get the flu vaccine at the same time as you get most other vaccines.

To find out more, read Flu vaccine FAQs.

When should I get the influenza vaccine?

You should have the flu shot every year. Most people only need one injection.

Some people need 2 shots, 4 weeks apart, such as:

  • children aged 6 months to 9 years old getting the flu shot for the first time
  • people getting the flu shot for the first time after a stem cell transplant, organ transplant or treatment called 'CAR T-cell therapy'

To find out more read Flu vaccine FAQs.

Other ways to prevent influenza

Good hygiene is one of the best ways to help prevent the flu and other illnesses from spreading. These are some things you should do to help prevent the flu:

  • Wash your hands regularly.
  • Cover your mouth and nose when coughing or sneezing.
  • Throw used tissues in the bin straight away.
  • Do not share cups, plates, cutlery and towels with other people.

Wearing a face mask can help lower your chance of catching the flu. This is because influenza spreads in droplets or smaller aerosols (particles in the air) when you talk, cough or sneeze.

If you are sick, you can:

  • avoid touching your eyes, nose and mouth
  • stay at home

Resources and support

Languages other than English

  • The Australian Government Department of Health, Disability and Ageing has translated their collection of resources about the flu (Opens in new tab) into many community languages.

Information for Aboriginal and/or Torres Strait Islander peoples

Last reviewed: February 2026

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