Allergens 101

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Index of Common Allergy Conditions

There are several different types of allergic conditions, each with its own set of symptoms. One or more of the common allergens — including dust/dust mite allergens, pollen allergens, pet allergens, and mold/mildew allergens — can cause these conditions

Allergic Asthma

Asthma is a chronic lung disease that is characterized by asthma attacks. During an asthma attack, or "flare," inflamed airways become narrowed — making it harder to breathe. There are two types of asthma: allergic and non-allergic ("intrinsic"). According to the Public Health Agency of Canada, asthma is a major public health problem in Canada.

To learn more about allergies and asthma, visit the Allergy/Asthma Information Association (AAIA) website at: and the Canadian Allergy, Asthma and Immunology Foundation at:


Getting vaccinated is the best protection against contracting the flu.

  • Coughing, which is sometimes uncontrollable
  • Chest tightness
  • Shortness of breath
  • Wheezing

For more on asthma, visit the Public Health Agency of Canada website at:

To learn more about common triggers for non-allergic asthma (inflammatory triggers), visit the Asthma Society of Canada website at: .

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Eye Allergy (Allergic conjunctivitis)

This condition occurs when eyes are exposed to an allergen — usually pollen. With conjunctivitis, the membrane (whites) of the eye and the inside of the eyelid become irritated and inflamed. Eye allergy can happen alone or in conjunction with hay fever (seasonal rhinitis).


  • Red eyes
  • Itchy eyes
  • Watery eyes
  • Swollen eyes
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Allergic Rhinitis

Rhinitis actually means inflammation of the nasal passages. This general term is used to describe the nasal congestion, sneezing and runny nose you can get due to allergies. Dust/dust mite allergens, pollen allergens, pet allergens, and mold allergens can cause rhinitis.

The allergic rhinitis caused by pollen is seasonal, and is often called "hay fever." But indoor allergens like dust mite allergens, pet allergens and mold allergens can cause rhinitis year-round. In addition, rhinitis is sometimes complicated by sinusitis, which is inflammation of the sinus cavities. Rhinitis can also trigger ear infections.


  • Sneezing
  • Stuffy or runny nose
  • Itchy nose or eyes
  • Itching on the roof of the mouth
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Food, medications, insect stings and exposure to latex can trigger anaphylaxis — a serious allergic reaction that happens quickly. Airborne allergens do not cause anaphylaxis.

People with food allergies, in particular, may have severe and even life-threatening reactions if they eat a food they are allergic to. The most common food triggers are milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts


  • A feeling of warmth/flushing
  • Tingling in the mouth
  • A red, itchy rash
  • Light-headedness and/or shortness of breath
  • Throat tightness
  • Stomach pain/cramps and/or vomiting and diarrhea.
  • In severe cases: drop in blood pressure that leads to unconsciousness and shock.

Anaphylaxis should be treated immediately with an injection of epinephrine (adrenalin). If you (or anyone you are with) begin to have an allergic reaction that could signal anaphylaxis, go to the closest emergency room immediately.

For more on this extremely serious allergic disease, visit the Anaphylaxis Canada website at: .

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Dermatitis: Eczema (Atopic) and Contact

Atopic dermatitis is also called eczema. This common allergic condition is caused by allergen exposure to the skin. Eczema is an itchy rash that often occurs on the hands, arms, legs and neck, although it can cover the entire body. It can be triggered by airborne allergens like pet dander and dust mites. Contact dermatitis, on the other hand, is caused by direct contact with a substance that is causes a skin reaction (like latex or poison ivy), but not by common airborne allergens.


  • Itchy, red and flaky skin
  • Peeling of the skin

For more on this extremely serious allergic disease, visit the Eczema Society of Canada at: and the Canadian Dermatology Association at:

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Hay Fever (Seasonal Rhinitis)

Seasonal allergic rhinitis is more commonly known as "hay fever." It's usually caused by an allergy to the pollen of plants, trees, or grasses. Depending on where you live and the pollen(s) you are allergic to, hay fever can happen in the spring, summer and/or fall — and could last until the first frost. Seasonal allergies also can trigger allergic asthma.


  • Sneezing
  • Itchy and/or runny nose
  • Itching and watery eyes
  • Burning or itching on the roof of your mouth and/or your throat
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Hives (Urticaria)

Urticaria, or "hives," can be caused by exposure to a allergen like food, medication or latex. Hives are not triggered by airborne allergens. Hives can be of any size and appear anywhere on the body. According to the Allergy/Asthma Information Association, approximately 25% of the Canadian population will have hives at least once in their lives.


  • Itchy red bumps or swollen areas, often in clumps

For more on hives, visit the Allergy/Asthma Information Association at:

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Sinus Infection (Allergic Sinusitis)

This condition is caused by the swelling of the sinus cavities. The sinus cavities are the hollow spaces located behind the cheekbones, which is why your face can feel sore or tender to the touch if you have sinusitis.

A sinus infection can start as a cold but it is also often triggered by allergic rhinitis caused by allergens like pet dander.

Symptoms of Sinus Infection:

  • Pain in the forehead, teeth or face
  • Coughing
  • Dark yellow or green nasal discharge
  • Itchy eyes and sneezing

Read more about Colds and Flu.

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Cold versus Allergies

Some allergic conditions, especially seasonal hay fever and allergic rhinitis, are easily confused with the common cold. That's because the symptoms are quite similar.

However, there are some general guidelines for determining "which is which," to allow you to take proper steps to relieve your condition and symptoms.


  • Symptoms last up to several weeks
  • Occurs in a "pattern," cropping up at the same time each year or after exposure to certain settings/situations
  • Often includes "itchiness" in the nose or eyes
  • Often include frequent sneezing and/or watery eyes
  • Membranes inside nose may be swollen and pale or bluish in color
  • Nasal discharge is clear and watery


  • Lasts for only 7-14 days.
  • Mucus is greenish/yellow.
  • A fever is possible, but is rare.

For more on cold symptoms and prevention, visit Colds and Flu..

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