Influenza (the flu) is a highly contagious disease, usually prevented by vaccination and treated by managing symptoms. Spread by body fluids from infected people, symptoms include a runny nose and sore throat. Flu can affect anyone but is especially serious for babies and older people.
What is the flu?
The flu is caused by the influenza virus. There are many different strains and they can change every year.
Flu is not the same as a common cold. The flu is a serious disease because it can lead to:
- ear infections
- heart and other organ damage
- brain inflammation and brain damage
The flu is easily spread from person to person. Most infections happen in winter.
Flu symptoms include:
- runny nose or sneezing
- cough or sore throat
- fever and chills
- body aches
- vomiting and diarrhoea (more common in children).
Symptoms usually start about 1 to 3 days after catching the flu and can last for a week or more. Some people can be mildly affected, while others can become seriously ill.
A common cold is not the same as the flu, although some of the symptoms are similar:
- runny nose or sneezing
- cough or sore throat.
Who is at risk
The flu can affect people of all ages.
People at highest risk of being hospitalised with flu are:
- people more than 65 years old
- Aboriginal and Torres Strait Islander people
- pregnant women
- people with long-term medical conditions
- people who have weakened immune systems
- people who are obese
- people who smoke
- people who haven’t been vaccinated against the flu.
Long-term medical conditions that can lead to you having a serious case of the flu include:
- heart disease
- Down syndrome
- lung disease
- conditions of the nervous system (such as multiple sclerosis)
- liver disease
- kidney disease
- blood diseases
- metabolic disorders.
How it spreads
The flu spreads:
- when an infected person coughs or sneezes, and you breathe it in
- through direct contact with fluid from an infected person’s coughs or sneezes
- by touching a contaminated surface with the flu virus on it, and then touching your mouth, eyes or nose.
The flu spreads easily through families, workplaces, childcare centres and schools.
If you have the flu, you can be infectious to others from 24 hours before symptoms start until 1 week after the start of symptoms.
If you have the flu, you can help stop the disease spreading by:
- staying away from childcare, school, work or other places where they could spread the infection until you are well
- covering your coughs and sneezes
- washing your hands often.
Vaccination is the best protection against the flu.
The flu vaccines protect you from getting infected and prevent serious disease. The flu strains constantly change so you need a new vaccine every year to make sure you stay protected.
Find out more about getting vaccinated against the flu.
Your doctor can diagnose the flu by:
- checking your symptoms
- asking if you’ve been in contact with someone who has the flu
- swabbing your nose or throat or taking a blood sample to test for the virus.
If you have flu your doctor may be required to notify your state or territory health department.
Mild flu gets better on its own without any treatment.
You can relieve the symptoms by:
- drinking fluids, particularly water
- taking paracetamol to reduce pain and fever
- using decongestant medicines.
People with a serious case of the flu may need to go to hospital. Even with treatment, some people with severe flu may die.
If diagnosed, you may be given medicines which if given early can help shorten how long illness lasts.
Antibiotics should not be used to treat colds or the flu, which are viral — not bacterial — infections.