Asthma overview

What is asthma?

Asthma is a chronic (ongoing) health condition characterised by inflammation of the airways of the lungs. This inflammation makes the airways highly sensitive — known as airway hyperresponsiveness. More than 2 million Australians are affected by asthma, a condition that causes the airways in your lungs to narrow intermittently.

Because people with asthma have sensitive airways, when they are exposed to certain triggers (such as some medicines or things to which they are allergic), their over-sensitive airways narrow, reducing the airflow through them, resulting in noticeable asthma symptoms. This airway narrowing, which makes breathing difficult by reducing the amount of air that can travel in and out of the lungs, is due to:

  • inflammation and swelling of the airways;
  • excessive production of thick mucus in the airways; and
  • tightening of the bands of smooth muscle around the airways (known as bronchoconstriction).

narrowing of airways during asthma attack

Lots of factors contribute to the development of asthma — for example, a family history of asthma, or a personal or family history of eczema or allergic rhinitis (hay fever). In addition, many things can trigger asthma symptoms if a susceptible person is exposed to them. These causes and triggers of asthma vary from person to person.

Asthma symptoms

The characteristic symptoms of asthma include:

  • breathlessness;
  • wheezing (a whistling sound in the chest);
  • chest tightness; and
  • cough.

Once an episode of airway narrowing resolves (either on its own or with treatment) the airflow into and out of the lungs returns to normal, and symptoms improve.

What triggers asthma symptoms?

For many people with asthma, it is an allergy that brings on (‘triggers’) their asthma symptoms. But some people have asthma that does not involve an allergic reaction; for example, you may only have asthma after vigorous exercise — so-called exercise-induced asthma.

The table below shows some common asthma triggers — those that are allergens (substances that provoke an allergic reaction) are on the left, and those that can trigger asthma symptoms but do not involve an allergic reaction are on the right.

Common asthma triggers
(substances that produce an allergic reaction)
Other triggers
  • Dust mites and their droppings
  • Pollens (usually from grasses, trees or weeds, rather than flowers)
  • Animal or bird allergens: dander (skin scales or flakes from hair or feathers); saliva or urine
  • Moulds
  • Cockroach allergen (cockroach droppings found in the dust of houses where cockroaches are present)
  • Occupational allergens (e.g. sawdusts, flour and latex)
  • Some medicines, such as aspirin
  • Air pollution (including cigarette smoke)
  • Exercise
  • Emotions and emotional reactions such as stress, anxiety, hearty laughing or crying
  • Heartburn (reflux)
  • Viral respiratory infections (colds and flu)
  • Cold air and ambient temperature changes
  • Some food additives (sulphur dioxide is the food additive thought most likely to trigger asthma)

Diagnosing asthma

To confirm a diagnosis of asthma, your doctor will ask questions about your symptoms, perform a physical examination, and conduct some lung function (breathing) tests, such as peak flow tests and spirometry.

Peak flow tests use a peak flow meter to measure the speed of air flow out of the lungs. A spirometer can measure how much air is blown out with each breath, and how much air you can blow out in one second. It can also test the effect of asthma medicines on your breathing — if symptoms and lung function are improved with asthma medicines, then that can help to confirm a diagnosis of asthma.

Asthma treatments

Asthma treatment usually involves managing your asthma with medicines, as advised by your doctor. Medicines for asthma are divided primarily into relievers and preventers.

Relievers: these medicines are known as bronchodilators because they help to open up the airways, helping you to breathe more easily when you're having difficulty. Unless advised otherwise by your doctor, relievers should be used on an ‘as-needed’ basis for the relief of asthma symptoms.

Preventers: these work by reducing the underlying inflammation of the airways, helping to reduce the incidence and severity of episodes of asthma. Unlike reliever medicines, you should take your preventer every day, as prescribed by your doctor, to help keep your asthma under control.

Some asthma products contain a combination of a preventer and a reliever to help keep asthma under control.

Most asthma medicines are delivered by an inhaler device, although some are available in tablet form. There are also some medicines — used in specific circumstances, such as treating asthma flare-ups — that are given via injection.

There is currently insufficient evidence from clinical trials to support the use of any complementary therapies in the treatment of asthma. The National Asthma Council recommends that the use of complementary therapies should not take the place of conventional treatments for asthma.

What can you do to help control asthma?

By avoiding or treating the triggers that set off your asthma, monitoring your asthma symptoms and taking your asthma medicines, you can help prevent asthma attacks. Ask your doctor to arrange an individual asthma management plan to help you achieve good asthma control.

So, you can help keep your asthma symptoms under control by:

  • visiting your doctor regularly for check-ups to ensure that you are taking the correct medicines for your asthma, and using your inhaler correctly;
  • making sure you have an asthma action plan that is written down and readily available;
  • being aware of symptoms and signs of worsening asthma (for example, needing to use your reliever medicine more frequently, or peak flow meter scores that are lower than normal);
  • using prescribed medicines regularly, as instructed by your doctor;
  • stopping smoking; and
  • avoiding asthma triggers whenever possible.
Last Reviewed: 1 September 2014

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1. National Asthma Council Australia. Australian Asthma Handbook, Version 1.0. National Asthma Council Australia, Melbourne, 2014. Website. Available from: (accessed Aug 2014).
2. National Asthma Council Australia. Australian Asthma Handbook – Quick Reference Guide, Version 1.0. National Asthma Council Australia, Melbourne, 2014. Available from: (accessed Aug 2014).
3. National Asthma Council Australia. Asthma and lung function tests (updated Feb 2013). (accessed Aug 2014).


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