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ARCHIVED - Allergies
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What Are Allergies?
Allergies are unpleasant at the very least, but they can also trigger dangerous reactions in certain people. Scientists use the word "allergy" to mean any kind of altered state of the immune system when it reacts differently to a substance as a result of previous contact.
There are two broad types of allergies:
- Immediate hypersensitivity is the common kind of allergy that causes hay fever, allergic asthma, food allergies and some drug allergies. People with this condition have a reaction within minutes of exposure to the allergen in question.
- Delayed hypersensitivity is a peeling eczema-like rash called "contact dermatitis" and is triggered when an allergen comes into contact with the skin. This type of reaction is much slower and usually takes two days to become obvious.
What Causes Allergies?
- People are not born with allergies, but become allergic as a result of contact with the things that cause them. You can't have an allergy to grass pollen, for example, unless you have been exposed to grass pollen in the past;
- There are a number of different inherited genes which can cause a person to become "atopic", the term used for people who have a tendency to develop allergies;
- People who develop one allergy are more likely to develop others;
- House dust mites, which grow in warm, humid and dusty environments, are the source of one of the most powerful biological allergens; and some mould species also contain allergens.
Photo: King Wan Wu, Agriculture and Agri-Food Canada
Symptoms of Allergies
The following symptoms generally occur quickly after exposure and reactions vary in severity, depending on the person, their overall state of health, age, and the length and intensity of the exposure:
- Coughing;
- Wheezing;
- Shortness of breath;
- Sneezing;
- Red, itchy and swollen eyes; and
- Flushed face.
How Do I Prevent or Fix the Problem?
If you suspect you may be allergic to one or more substances, contact your doctor to assess the severity of your condition. You may require medicine to control your reactions.
General Tips for Reducing Exposure to Potential Indoor Allergens:
- Regularly vacuum-clean your floors and carpets
- Keep your home mould-free
Where Can I Get More Information?
Health Canada Resources
Other Resources
People who develop one allergy are more likely to develop other allergies.
