What are the symptoms of influenza A?

If you have influenza A, you will have some or all of these symptoms: fever and chills headache and muscle aches feeling tired and weak sneezing, and stuffy or runny nose sore throat and cough Children may also have abdominal pain, nausea and vomiting. Influenza A is a bit like a very bad cold, but a cold doesn't usually cause aches and pains or a high fever. If your symptoms get worse instead of better, it's best to see a doctor. You should also get help straight away if you feel chest pain, you are short of breath, dizzy or confused, or you are vomiting a lot.

How is influenza A treated?

If you have influenza, you are likely to get better within a week or so by: resting in bed taking mild pain relief to reduce your pain drinking plenty of liquids eating light foods when you are hungry In some people, the flu can be severe and lead to serious complications such as pneumonia. This is mostly likely to affect the very young, the elderly, pregnant women, Aboriginal and Torres Strait Islander people, and people with chronic health problems. If this sounds like you, your doctor might give you antiviral treatment to reduce your symptoms and prevent complications. These treatments are most effective when started within 2 days of flu symptoms appearing, so it’s important to ask your doctor whether this type of treatment is right for you. Antibiotics only work for bacterial infections, so they won't work for the flu, which is caused by viruses.

Can influenza A be prevented?

Influenza spreads very easily from one person to another. If you have influenza, you should stay at home while you're sick, cover your face when you sneeze or cough, and regularly wash your hands. If you are around someone with influenza, you can help avoid getting sick yourself by regularly wiping surfaces they touch, using a cleaning cloth with detergent, and washing your hands. Getting vaccinated each year before winter arrives is the best way to protect against influenza A. A new vaccine is needed every year because influenza viruses change constantly. Flu vaccine is available for everyone aged over 6 months. The vaccine is particularly recommended if you are at risk of complications of influenza, or if you live or work with people at high risk of getting the flu. Should I keep my child home from school? Here’s a list of common childhood illnesses, including Influenza A, and their recommended exclusion periods.

Influenza A

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Key facts

Influenza A is a type of virus that causes the flu. Most people who have flu are infected with the influenza type A virus.
Symptoms of Influenza A include fever and chills, sneezing, coughing and a sore throat.
As well as infecting people, the influenza A virus can infect animals, including birds and pigs.

What is influenza A?

Influenza A is a type of virus that causes influenza (the flu), a highly contagious respiratory illness. If you get it, you will need to rest at home and avoid infecting others. Vaccination can protect you against influenza A.

The other types of influenza virus are type B and type C.

Influenza types A and B are the most common causes of flu in Australia and can cause major outbreaks and severe disease. Influenza type C can cause an illness in children that is similar to the common cold.

Most people who have flu are infected with the influenza type A virus. This virus has caused flu pandemics — the worldwide spread of a new disease. Influenza A has also caused most epidemics — the widespread occurrence of an infectious disease within a community at a particular time.

Although coronavirus (COVID-19), is a viral illness that has developed into a pandemic, the virus that causes COVID-19 is different from the one that causes influenza.

Both the influenza A and influenza B viruses circulate in the community and change continually, with new strains coming out each winter. This is why yearly vaccination is recommended.

What are the types of influenza A?

As well as infecting people, the influenza A virus can infect animals, including birds (causing avian flu) and pigs (causing swine flu). In some cases, these types of influenza can be passed on to humans.

Bird flu

Avian influenza — also known as 'bird flu' — is a subtype of influenza virus A (H5N1) that mainly affects birds. The virus has caused serious infections and even deaths in humans but has not been found in Australia.

Although bird flu can be severe, the number of cases found in humans has been small. Most people diagnosed with bird flu have caught it from infected birds — so far, there is no evidence that bird flu can pass from human to human.

Swine flu

Swine flu is a type of influenza A virus found in pigs. In 2009, a strain of flu virus known as H1N1 caused a respiratory infection in humans which spread rapidly around the world and became a pandemic. The World Health Organisation (WHO) declared the swine flu pandemic over in August 2010.

The 1918 flu pandemic was also caused by an influenza A H1N1 virus.

Swine flu is mild in most people but can be severe for some high risk groups such as people with chronic conditions, pregnant people and Aboriginal or Torres Strait Islander people.

Symptoms, treatment and prevention

If you have influenza A, you will have some or all of these symptoms:

fever and chills
headache and muscle aches
feeling tired and weak
sneezing, and stuffy or runny nose
sore throat and cough

Children may also have abdominal pain, nausea and vomiting.

In most cases you can treat the symptoms of a mild flu yourself by resting at home. Medicines are available to treat pain and fever. Most people will get better within 7 to 10 days.

The best way to prevent catching the flu is to have a flu vaccination every year, and to practise good hygiene.

For more information on treating flu symptoms, prevention and when to see a doctor, see Flu (influenza).

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