WHAT EXACTLY ARE ALLERGIES?
We’ve all heard the term “allergies.” It’s common knowledge that people can be allergic to a range of things: pollen, dust mites, molds, pet dander… the list goes on. But what is the definition of an allergy? What happens inside our bodies to cause allergy symptoms? What are common allergy symptoms? Are there different allergy seasons in Canada?
OUR IMMUNE SYSTEM AT WORK
Our immune system is designed to protect us from harmful invaders called “pathogens” [PATH-oh-jenz] such as viruses, bacteria, and fungi. To help protect against these invaders, our immune system produces highly specialized proteins called “antibodies” [ANN-tee-BAWD-eez]. The antibodies recognize harmful invaders by attaching to them and signal the immune system to send substances to destroy them.
An allergic reaction occurs when the immune system overreacts to a normally harmless substance, such as grass, pollen, pet dander or dust mites—known as an allergen. Your immune system reacts by producing antibodies. This is called “sensitization.” The next time your immune system encounters the pollen/pet dander/dust mites, the antibodies recognize it and tag it as an invader. The antibodies travel to certain cells that release chemicals, called histamines, causing allergy symptoms often found in the nose, throat ears, eyes, and skin. The result? Allergy symptoms.
WHAT ARE HISTAMINES AND WHAT DO THEY DO?
Histamines are always present in the body in small amounts but more get released when an allergen is present. The histamine reaction serves two main functions: 1. It causes “vasodilation” which is when the walls that surround blood vessels are relaxed, causing the interior of the blood vessel to widen. 2. It causes fluid to be released. The widening of the blood vessels allows white blood cells (infection fighters) to move easily to the site of the infection and fluid secretion helps the body get rid of the allergens. However, this release of fluids and vasodilation is what causes some of the more common allergy symptoms.
WHAT ARE COMMON ALLERGY SYMPTOMS?
Common allergy symptoms may appear in the eyes, skin, nose, throat and ears.
COMMON ALLERGENS
Allergies can be year-round or seasonal. Seasonal allergies tend to be due to pollen from trees, grass and ragweed. Mold allergy sufferers may notice their symptoms are worse in damp or humid weather.
Animal dander, the dead skin and hair from a pet, is a common year-round allergen. Another common year-round allergen is dust. What most people are allergic to in dust, is not the dust itself, which is made up of pet and human dander, but dust mite feces. Dust mites are tiny bugs that feed off the pet and human dander.
WHEN IS ALLERGY SEASON IN CANADA?
Spring (Late-April and May): tree pollen
Summer (Late-May to mid-July): grass pollen
Fall (mid-August to October): ragweed pollen
ALLERGY DEFINITIONS
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Allergy |
A chronic condition involving an abnormal reaction to an ordinarily harmless substance called an allergen. |
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Allergen |
A foreign substance that causes an allergic reaction. |
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Allergy symptoms |
When the body overreacts when exposed to a foreign substance which are mostly harmless in other people. |
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Antibodies |
Highly specialized proteins the body produces to recognize harmful invaders by attaching to them and signalling them to send substances to destroy them. |
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Histamine |
A naturally occurring chemical that causes many of the common allergy symptoms. |
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Immune system |
The body’s protection from outside invaders such as viruses, bacteria, fungi, and toxins. |
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Sensitization |
The body's first reaction to foreign substances with the production of antibodies. |
