Allergic triggers of asthma

Around two out of five Australians have allergies, including most people with asthma. Allergies tend to run in families but family members may not have the same response.

Allergies occur when a person’s immune system reacts to substances (allergens) that are harmless to most people.

These triggers can affect:

  • Breathing – asthma and hay fever
  • Skin – dermatitis, eczema and hives
  • Eyes – allergic conjunctivitis
  • Whole body – anaphylaxis (rare but very serious)

Most people are allergic to more than one trigger and sometimes the response is different, so you could get itchy eyes around cats but a runny nose during pollen season. The severity of the allergic reaction varies between people and depends on the circumstances. A reaction may not be immediate.

If you think you are allergic, speak to your doctor to help identify exactly what triggers your allergies and how you can best manage this. For example, you may have worked out you are allergic to pollen because you get hay fever in spring, but you may not know which plant is the culprit. Your GP or an allergist can do tests such as skin prick testing or serum-specific IgE (RAST) allergy tests to identify the trigger.

Common triggers

The best way to avoid an allergic reaction is to avoid the trigger that causes it, but this is not always possible. However, reducing exposure to your allergy triggers may make your symptoms easier to manage.

Bear in mind that efforts to avoid or reduce allergy exposure can be costly, time-consuming or impractical, and may not work for every person or circumstance.

If you’re keen to try, the first step is to know what triggers your allergies so you can focus your efforts in the right area.

Dust mites

They like moderate temperatures and high humidity. They are found in bedding, flooring, window coverings and furniture. Their poo is the main culprit and is small enough to become airborne when stirred up. Find out more.


Mould needs long periods of humidity to grow. Houses in tropical areas or with rising damp may be more at risk. Poor ventilation may mean a bathroom or built-in robe can produce mould, even if not in humid areas. Find out more.


Cats and dogs are the most common cause of pet allergies. Guinea pigs, rabbits, birds, mice and rats can also trigger asthma or allergies in some people. Find out more.


Trees, grasses and other wind-pollenated plants are the source of the most troublesome pollens. For many people, spring is the worst time, but some plants produce pollen in other months of the year. Find out more.


Both cigarette and wood smoke can cause or worsen asthma symptoms. Find out more.

Chemicals (VOCs/PGEs)

Volatile organic compounds (VOCs) may not be good for your lungs and are best avoided. Propylene glycol and glycol ethers (PGEs) may also be harmful. VOCs and PGEs are usually found in paint and cleaning chemicals. The main risk occurs when contents are wet or drying. Find out more.

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