Asthma explained

Asthma is a long-term (chronic) disease of the airways that can make breathing difficult. The exact cause of asthma is not known, but a proper treatment plan can help each individual manage their asthma and continue leading a healthy, active life.


What is asthma?

Asthma is a long-term (chronic) disease of the airways – the tubes that carry air in and out of the lungs.

A person with asthma has sensitive airways that narrow when exposed to certain triggers, which makes breathing difficult. This is called an asthma flare-up.

Each person with asthma has individual triggers that can lead to an asthma flare-up, but there are some common substances, like pollen, dust and smoke, that will usually irritate the airways of a person with asthma. When someone with asthma is exposed to these triggers, their airways become smaller, which limits the amount of air that can flow in and out of their lungs. This is because:

  • the layer of muscle around the airways tightens up
  • the lining of the airways becomes swollen and inflamed
  • the airways become blocked with mucus.

What are the symptoms of asthma?

Asthma symptoms vary from person to person. They are caused and intensified by certain triggers.

The most common asthma symptoms are:

  • shortness of breath
  • wheezing – a high-pitched raspy sound when breathing
  • tightness in the chest
  • persistent cough, especially at night, in the early morning, or with exercise or activity.

Some people with asthma may have all these symptoms, or only a wheeze or a cough. A person can still be diagnosed with asthma even if they don’t have these common asthma symptoms. 

When people with asthma are having difficulty with their breathing, it’s called an asthma flare-up. The sensation of an asthma flare-up has been described as feeling like you are breathing through a thin straw.

If a child is wheezing, does that mean they have asthma?

Wheezing is very common in children younger than 6 years old, particularly after a viral chest infection.

Most young children grow out of their wheeze but for 1 of every 3 children who wheeze, it is a sign of asthma.

In adults and children 6 years or older, asthma can be confirmed with a breathing test called spirometry. This test is not easy for younger children to do as it requires strength and coordination, which is why confirming asthma in this age group is tricky.

Don’t worry if your child is given asthma medication for their wheeze. The medicines used to treat asthma and wheeze are often the same, because they have the same purpose: to open the airways and help your child breathe more easily.

There are several conditions that may cause a young child to wheeze. It’s best to speak to a health professional to gain a better understanding of their symptoms.

What causes asthma?

More than 2.5 million Australians have been diagnosed with asthma. The exact cause of the condition is not known.

We do know that asthma is:

  • not contagious: you can’t ‘catch’ asthma or ‘spread’ it from person to person
  • related to a few risk factors, including genetics and the environment.

Some people are more likely to develop asthma than others. Some risk factors are:

  • a history of asthma in their family
  • a history of viral respiratory infections during childhood
  • conditions such as eczema or allergies like hay fever
  • exposure to tobacco smoke during childhood, especially if the person’s mother smoked during pregnancy
  • exposure to certain substances such as mould, air pollution or particular chemicals
  • being born prematurely or with a low birth weight (less than 2 kg)
  • obesity.

How is asthma diagnosed?

To diagnose asthma, a doctor will need to understand:

  • the type of symptoms experienced
  • how often symptoms occur
  • the times of day that symptoms occur.

The doctor will also ask if certain triggers make the symptoms appear or make them worse.

The doctor may also need information about the patient’s:

  • family history of asthma, eczema, or hay fever
  • current medicines
  • smoking status, or exposure to second-hand smoke
  • work, school and home environments.

After the doctor has this information, they are likely to listen to the patient’s lungs, airways and breathing, using a stethoscope.

They may also need to perform some tests to measure how well the lungs are working (lung function tests) in different scenarios.

Doctors usually confirm asthma using a lung function test called spirometry. This test measures how much air can move in and out of the lungs, and how quickly the air is travelling.

Spirometry may not be suitable for diagnosing asthma in some children, so if that is the case your doctor will use other information to make a diagnosis.

Having a proper asthma diagnosis makes it easier for a doctor to create an asthma treatment plan.

During the COVID-19 pandemic, you should not perform spirometry if you have a fever or an acute respiratory infection that is getting worse

Common asthma triggers

An asthma trigger is a substance, activity or environmental factor that makes breathing difficult for a person with asthma. When a person with asthma is exposed to a trigger, their airways become narrow and inflamed. Asthma triggers vary from person to person, and most people with asthma will have more than one trigger.

Common asthma triggers include:

  • respiratory infections such as the cold or flu – the common cold triggers around 4 in 5 asthma flare-ups
  • cigarette smoke
  • allergy-related triggers, such as pollen, dust mites, pet fur and mould
  • intense exercise (this kind of asthma is sometimes known as exercise-induced asthma)
  • changes in temperature or weather (usually cold weather)
  • work-related triggers, such as wood dust, chemicals and metal salts
  • inhaled irritants, such as perfumes or bushfire smoke
  • some medicines (eg, anti-inflammatory medicines called NSAIDs, including aspirin and ibuprofen)
  • some foods or other dietary substances such as food chemicals or additives/preservatives
  • stress, or expressions of emotion such as crying or laughing.

Knowing what triggers asthma for a person and avoiding it can help prevent symptoms. This is useful if someone is having symptoms of asthma even though they are taking their asthma medication regularly.

Some triggers can’t be completely avoided, so medicines may still be needed to help manage symptoms of asthma. Also, airways can still be inflamed when there are no triggers.

When a person with asthma has good asthma control, triggers are less likely to cause an asthma flare-up.

What is an asthma flare-up?

An asthma flare-up, sometimes known as an asthma attack, happens when asthma symptoms are worse than usual and don’t resolve on their own.

A flare-up can come on suddenly if a person with asthma is exposed to a trigger. A flare-up of asthma symptoms can also be gradual, for instance if someone with asthma is finding it increasingly harder to breathe because of a cold.

Flare-ups also vary in intensity. During a severe flare-up, a person with asthma will find it very hard to breathe but may no longer have a cough or wheeze. Other signs of a severe asthma attack include:

  • breathlessness, including being unable to do anything or even speak
  • racing pulse
  • feeling agitated or restless
  • lips or fingernails turning blue.

If someone is monitoring their peak expiratory flow (PEF) at home, a reduction in readings may happen during a severe asthma flare-up.

Call 000 for an ambulance immediately if someone is having a severe asthma flare-up and a reliever medicine isn’t helping. This is an asthma emergency.

Download a first-aid chart for an asthma attack from the National Asthma Council website

What treatments are there for asthma?

Everyone with asthma will be prescribed a reliever medicine. This is mostly used in the event of a flare-up to help making breathing easier.

Most adults with asthma will also need to take a preventer medicine on a regular (usually daily) basis, as prescribed by their doctor. Over time, preventers help make the airways in a person with asthma less sensitive and reduce the likelihood of flare-ups.

These medicines usually come in inhalers (also known as puffers) which deliver them directly into the lungs.

Children younger than 4 years will need to use a spacer and mask with an inhaler. It’s also recommended that adults and children 4 years and older use their inhalers with spacers.

There are also asthma medicines that come in nebuliser solutions or in oral tablets.

In a medical emergency, or in hospital, a person with asthma may need to be injected with asthma medicine.

It’s important to always check the expiry date on asthma medication, to make sure it’s current.

Find out more about medicines used to treat asthma

During the COVID-19 pandemic, people have been advised to avoid using a nebuliser, if possible, as this may increase the risk of spreading respiratory infections to others.

Having an asthma action plan

Everyone with asthma should have an asthma action plan written by their GP or practice nurse. This plan will help a person with asthma recognise when their symptoms are becoming worse and identify the medicine, or action, they need to take in that scenario.

Following the instructions provided in an asthma action plan can reduce the risk – or intensity – of an asthma flare-up.

The plan should include the following information:

  • a list of medicines (with doses) that the person with asthma is taking when they are feeling well
  • a list of signs that identify if a person with asthma is experiencing a flare-up
  • a list of medicines (with doses) to take during a flare-up
  • clear information on when a person with asthma needs medical attention
  • clear information on when a person with asthma needs an ambulance
  • phone numbers of emergency contacts
  • name and contact details of the person's GP and the date when the plan was written.

If your child has asthma, it’s a good idea to make extra copies of the plan and hand it out to regular carers, such as grandparents, as well as teachers and early childhood educators. It might be helpful to note the location of your child’s reliever on the plan itself, so that it can be found easily during an asthma flare-up.

If you, or your child, haven’t received an asthma action plan, ask your GP or practice nurse to fill one out for you as soon as possible. You can download a print-friendly version on the National Asthma Council website and bring it to your next appointment.

An asthma action plan should be updated if there are any changes to asthma treatment.

Having an up-to-date action plan is particularly important during this COVID-19 pandemic.