Allergens

  • Canola allergen - large There is a close link between asthma and allergy and around 40% of Australians have some form of allergy, while more than 80% of people who have asthma also have an allergy.

    Our immune system is a major part of the body’s defence mechanism against foreign “invaders” (especially bacteria, viruses, parasites and other harmful things) that are present in the air we breathe, the food we eat and the things we touch.

    An allergy is your body’s response to a substance that it decides is harmful. This is an abnormal response. It  may cause inflammation in a specific area of the body such as the nose, eyes, skin or lungs. Common allergens include the house dust mite and pollen.

    Something that is an allergen for one person may not be for another, and everyone reacts differently.

    What is an allergic reaction?

    An allergic reaction is a complex chain of events that involves many cells, chemicals and tissues in your body.  It results in inflammation in the skin, lungs, gut, nose and/or eyes. This may cause symptoms such as swelling, redness and itch in the skin; watery, itchy nose with sneezing and blockage; watery, red itchy eyes; wheezing, coughing and mucus production in the lungs. This reaction begins when a person who is allergic comes into contact with the allergen “invader” to which they are sensitive.

    Asthma symptoms can occur when an allergen is breathed into the lungs of a sensitive person. This leads to swelling of the lining of the airways and tightening of the muscles around the airway which causes narrowing of the airway and so difficulty in breathing.

    Note: Allergens are common asthma triggers, however not all asthma is caused by allergy, and not all allergies lead to asthma.

    For information on hayfever and skin conditions see hayfever and eczema.

    Lungs allergens - smallAllergy tests

    The most common ways of allergy testing are skin tests, blood tests and diet-control tests.

    • Skin tests

    Skin prick testing is usually done on the forearm. The arm is cleaned and then a drop of allergen is put on the skin. A small prick into the skin is made to allow a small drop of allergen to enter the skin. If you are allergic, a small lump (like a mosquito bite) will appear over 15-20 minutes. Skin prick testing should only be performed by a trained health professional who knows how to interpret the results.

    • Blood tests

    Blood testing may be performed if skin testing is not possible or is inconvenient. This involves taking some blood and checking for antibodies to specific allergens.

    • Diet control tests

    Elimination diets may be used to investigate possible food-related symptoms. For possible adverse food reactions, the foods that are suspected to be causing symptoms are removed from the diet for a time, and then slowly re-introduced one at a time to check your response.

    Such diets are rarely needed for investigation of true food allergies, although occasionally in people with atopic dermatitis this approach may be used. 

    Allergy test results

    If allergy test results are negative (i.e. you don’t respond to the allergen) it means you are not allergic. If you have a positive result, it means you reacted to an allergen. Usually the stronger the response, the more sensitive you are to that substance. However, people can have a positive response to skin prick testing but not have any reaction to the substance in their normal life. So test results should be considered along with whether you have experienced a significant reaction to those substances in the past.

    Other allergy tests

    Be cautious about the many different allergy tests you may see advertised. The tests mentioned above (specific IgE blood tests, skin prick testing) have been scientifically validated and should be carried out by a health professional who knows how to perform the test and interpret the results. They also know how to treat any allergic reactions that may occur immediately.

    Other methods that claim to test for allergic responses that have not been scientifically evaluated include:

    • reflexology
    • kinesiology
    • Vega testing
    • pulse testing and
    • hair analysis
    Managing asthma and allergy

    Before you make any changes to your home or lifestyle, you should check if you really do have an allergy by seeing your doctor for allergy testing. If you do have an allergic response, you can talk with your doctor about how to manage the allergen. Your doctor may prescribe medication and advise how to reduce your exposure to your allergen triggers if appropriate. They may also update your Asthma Action Plan.

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