Most people with asthma have allergies. Allergies occur when a person’s immune system (the process that protects against disease) reacts to substances in the environment that are harmless to most people. These substances are known as allergens. Examples of allergens include house dust mites, pollen, mold, and pet dander. Sensitivity to allergens can often be identified via blood or skin tests.
Perfume and cigarette smoke can also trigger asthma in some people. However, these do not involve a reaction in the person’s immune system. These are called non-allergic irritant triggers. There are no skin or blood tests for non-allergic irritant triggers.
Allergy may run in families. ‘Atopy’ is the genetic or inherited tendency to develop allergic diseases. When individuals with allergic tendencies (atopy) are exposed to allergens, they can develop an immune reaction that leads to allergic inflammation (redness and swelling). This can cause symptoms in the:
- Nose and/or eyes (allergic rhinitis/conjunctivitis, hay fever)
- Skin (eczema, hives)
- Lungs (asthma)
If you have asthma that is triggered by allergens, you may have asthma symptoms when you are exposed to:
- Dust, including from a vacuum which can causes house dust mite allergens to become airborne
- Pets or a house where pets live
- Pollen, particularly during the late spring and early summer, when there are high levels of pollen in the air
- Mold
Asthma symptoms can also be triggered by workplace-related allergens, such as flour and grain dust, latex, and animal allergen (e.g. urine, dander). Due to the close link between asthma and allergy, it can be more difficult to manage asthma when an individual’s allergies are not treated.
Unlike other asthma triggers, such as colds and flu, it might be possible to avoid or reduce exposure to some allergen triggers of asthma.
Your doctor, nurse practitioner or pharmacist can help determine if allergy plays a role in your asthma (see below information on allergy tests). Once this is determined, your healthcare team will be better able to:
- Advise on how to reduce or avoid exposure to your allergies
- Prescribe appropriate medicine
- Determine if immunotherapy is suitable for you
It is important to determine which allergens trigger your asthma. Avoiding or reducing exposure to these allergens may be an important part of managing your asthma.
Allergy tests
The two main allergy tests are
skin prick tests, and
blood tests for serum specific IgE* (previously referred to as RAST** tests). These tests identify antibodies to specific allergens.
Sometimes an alternative testing method is used to test for allergy. Called scratch testing, this method is used when greater sensitivity in the testing is needed. Most doctors will not rely on allergy tests alone but will also consider an individual’s medical history. Your doctor may also refer you to an allergy/immunology specialist for further tests.
Allergy tests should only be performed by a doctor or nurse who has been trained in the procedure, and knows how to interpret the results.
Common allergic triggers of asthma
Complete allergen avoidance does not cure asthma; however, reducing exposure to allergen triggers may improve your asthma control and make your asthma symptoms easier to manage.
Efforts to reduce or avoid allergen exposure are best attempted if:
- Your doctor has advised that you have a proven allergy to the trigger
- Exposure to the trigger causes your asthma symptoms
- You are motivated to try several allergen exposure reduction measures. Following just one measure is unlikely to make a difference
Remember, allergen avoidance or reduction strategies should be used in combination with your recommended medicines. These do not replace your doctor’s advice.
