Influenza (flu) is a highly contagious respiratory illness. Flu is more serious than the common cold and severe cases can result in breathing difficulties and pneumonia. If you have flu symptoms, or have been diagnosed with flu, it is important to stay home and avoid contact with others until your symptoms have gone.​

Last updated: 04 June 2024
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​​​​​​​​​What is influenza (flu)?

Influenza (flu) is a highly contagious respiratory illness caused by influenza viruses. There are two main types of human influenza viruses: A and B. There are also many sub-types and strains. Flu is more serious than the common cold. Severe cases can result in breathing difficulties and pneumonia. People in NSW can die from flu-related illness.

Flu can occur throughout the year but is most common in autumn and winter. In most flu seasons there is more than one strain circulating in the community.

What are the symptoms of flu?

People with flu often experience some or all the following symptoms:

  • fever and chills
  • cough, sore throat and runny or stuffy nose
  • muscle aches, joint pains, headaches and fatigue (feeling very tired)
  • nausea, vomiting and diarrhoea (more common in children than adults).

Symptoms of flu may last for more than a week. Some people only have mild symptoms for a few days, particularly if they have some immunity from a previous infection or vaccination. Other people can get very sick from the flu and may have complications such as lung infection (pneumonia) or severe breathing difficulties requiring hospitalisation. These complications can occur in anyone but are most likely in those at higher risk of severe illness.

How is flu spread?

Flu is mostly spread by droplets made when people with flu cough or sneeze. It can also be spread by touching a surface or object that virus droplets have landed on from an infected person. People with influenza can spread it to others before they are sick as well as while they are sick.

If you have flu symptoms, or have been diagnosed with flu, it is important to stay home and avoid contact with others until your symptoms have gone.

How is flu diagnosed?

The only way to confirm a diagnosis of flu is to have a PCR (nose and throat swab) test.

Speak with your doctor to find out if you should get a referral to have a PCR test for influenza. There are antiviral treatments that are available for people people at higher risk of severe illness from flu.

How long are people infectious?

  • People with flu can be infectious from the day before their symptoms start.
  • Adults are most infectious in the first 3-5 days of their illness.
  • Children can remain infectious for 7-10 days.
  • Young children and people with weakened immune systems may be infectious for longer.

Who is at higher risk of severe illness?

While anyone can get flu, some people are at higher risk of severe illness (more likely to get very sick from flu, and may be at higher risk of needing hospital care), including:

  • babies and children under 5 years of age
  • people aged 65 years and older
  • Aboriginal and Torres Strait Islander people
  • pregnant women, at any stage of pregnancy
  • people with certain medical conditions including heart disease, chronic lung conditions (including severe asthma), kidney disease, liver disease, diabetes, obesity, chronic neurological conditions, blood disorders, immunocompromise, and other chronic conditions in children and adults that need regular medical follow up or hospitalisation.

If you are homeless or living in an aged care or long term care facility, you may be at increased risk of severe illness. If you are unsure of your risk, speak to a doctor.

How do I protect myself and others?

Get your annual flu vaccine

  • Everyone aged 6 months and over is recommended to get an annual flu vaccine to protect themselves from influenza.
  • People at higher risk of severe illness from flu may be eligible for a free flu vaccine under the National Immunisation Program.
  • Flu vaccination for those people who regularly come into close contact with people at higher risk of severe illness from flu (such as health and residential care workers and family members) will help protect those at higher risk.
  • A flu vaccine is needed every year as influenza virus strains change (mutate) constantly. A vaccine is prepared each year to best match the strains predicted for the coming flu season. Vaccination is very effective in preventing serious illness from the influenza virus.

Have a plan if you are at higher risk of severe illness

If you are at higher risk of severe illness, you should talk to your doctor before you get sick to make a plan for what test to do and what treatment you may need. There are antiviral medicines available to prevent and treat flu. Your doctor can fill out an antiviral pre-assessment action plan and you can discuss which treatment best suits you.

If you have influenza, your doctor will still need to provide a prescription for antiviral medicines but having a plan will help you access antiviral medicines quickly and easily.

Follow other simple steps to protect yourself and others

There are simple steps to help protect others, including: 

  • Stay home if you have cold or flu symptoms and wear a mask if you need to leave home
  • Get together outdoors or in large, well-ventilated spaces with open doors and windows
  • Avoid crowded places
  • Don't visit people who are at higher risk of severe illness if you have cold or flu symptoms
  • Practice good hand hygiene, including regular handwashing.

How can I manage flu safely?

Stay at home and reduce risk to others

If you are sick with flu, stay at home and avoid close contact with other people. Keep sick children away from school and other activities. To avoid infecting others, stay at home for at least 24 hours after your fever has resolved and until you are feeling well. This is especially important if you visit people at higher risk of severe illness, including pregnant women, infants, older people and people in hospital, residential aged or disability care.

Start antiviral medicines early if you are eligible

People at higher risk of severe illness from flu may be eligible for antiviral medicines such as oseltamivir (Tamiflu®). Antiviral medicines may reduce severe illness, hospitalisation and death from flu if taken early in the illness. It is important to contact your doctor as soon as possible to determine if you are able to take antiviral medicines. To be most effective, antivirals should be taken within 48 hours of when symptoms start.

Monitor your symptoms

Most symptoms can be managed with:

  • plenty of rest
  • regular paracetamol and ibuprofen to relieve pain and fevers as needed (children under 16 years of age must not be given aspirin-containing medications)
  • staying hydrated with regular sips of water.

Know when to get help 

If you get any of the following symptoms call Triple Zero (000) immediately and tell the ambulance staff you could have flu:

  • shortness of breath or rapid breathing​
  • chest pain or pressure lasting longer than ten minutes
  • confusion or sudden dizziness
  • persistent vomiting. ​

If you have flu and have health questions that are not a medical emergency, contact your doctor or call healthdirect on 1800 022 222. Healthdirect​​​​ is free and available 24 hours a day, 7 days a week. A registered nurse will answer your call, ask some questions and connect you with the right care.  

Further information