Allergy and Asthma (PDF)
This information sheet outlines the process by which an asthma attack can be triggered by an allergic reaction.
An individual exposed to a substance and over a period of time can become sensitised to it and future exposure will trigger an allergic reaction. This could be in the form of eczema, hives, hay fever, a runny nose or an asthma attack.
An allergen is a substance that generates an allergic reaction. There are a number of different allergens that can trigger asthma in different people. These are usually inhaled but may be swallowed, injected or applied to the skin. Sometimes more than one part of the body can be affected at one time. This is why many people with asthma also experience hay fever and eczema.
Allergens include:
· dust / dust mites
· pollens
· animal dander (dead skin flakes)
· moulds
· some foods
True allergic reactions differ between people. Some people have mild reactions while others have severe or even fatal reactions. Some reactions start within minutes and wear off within hours. Other reactions start hours after exposure and go on for days.
An allergic reaction occurs when an allergen is inhaled into the lungs of a sensitised person and it sets off a series of chemical reactions that lead to inflammation (swelling, redness) muscle contraction and narrowing of the airways resulting in an asthma attack.
It is important to try and identify the allergen if possible. This is usually done by association between exposure and an attack or aggravation of asthma. Skin prick tests or blood tests can indicate the likelihood of a substance as a trigger. However, a reaction to these tests does not necessarily mean the substance reacts in the lungs. Identification of an allergen as a trigger might enable an individual to avoid it.
Further information on allergies, anaphylaxis, hay fever and eczema can be found at
www.allergy.org.au.