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ALLERGY 101:
CAUSES AND SYMPTOMS

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

Allergy

A chronic condition involving an abnormal reaction to an ordinarily harmless substance called an allergen.

Allergen

A foreign substance that causes an allergic reaction.

Allergy symptoms

When the body overreacts when exposed to a foreign substance which are mostly harmless in other people.

Antibodies

Highly specialized proteins the body produces to recognize harmful invaders by attaching to them and signalling them to send substances to destroy them.

Histamine

A naturally occurring chemical that causes many of the common allergy symptoms.

Immune system

The body’s protection from outside invaders such as viruses, bacteria, fungi, and toxins.

Sensitization

The body's first reaction to foreign substances with the production of antibodies.

Image of a Woman Sneezing Due to Allergies

What exactly are allergies?

Allergies are chronic conditions involving an abnormal reaction to an ordinarily harmless substance called an allergen.

LEARN MORE
Skin Prick Allergy Test

What are common allergy triggers?

Learn more about different potential triggers of various allergy types such as dust mites, pollen, ragweed, pet dander and mold.

LEARN MORE
Image of a Woman Suffering from Cold and Allergy Symptoms

Is it a cold or allergies?

Find out the differences between cold and allergy symptoms.

LEARN MORE
A Woman with Red Eyes Caused Due to Eye Allergies

Symptom Spotlight: Eye

A closer look at how allergies manifest in the eyes

LEARN MORE
A Woman Suffering from Itchy Skin Due to Skin Allergies

Symptom Spotlight: Skin

Allergic skin reactions can be more than skin-deep.

LEARN MORE
A Man Sneezing Due to Nasal Allergies

Symptom Spotlight: Nose

Understanding allergic nasal congestion and sneezy, runny noses.

LEARN MORE
Image of a Woman Suffering from an Ear Allergy

Symptom Spotlight: Throat & Ears

The facts on throat and ear allergy symptoms can be hard to swallow.

LEARN MORE

To be sure this product is suitable for you, always read and follow the label.

IMPORTANT NOTE

This website is intended for information purposes only and is in no way intended to substitute for professional medical advice, to contradict medical advice given, or for medical care of any kind. As with any medication, speak to your doctor before using. Please review the Conditions of Use before using this website. Your use of this website indicates your agreement to be bound by the Conditions of Use.

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