Health A to Z


Are your allergies harmless or hazardous? Find out with this breakdown.

Allergy causes symptoms treatment

If you find you’re getting one too many colds, all that sniffling and sneezing may actually be caused by allergies, which occur when your immune system overreacts to a substance that is normally harmless, called an allergen, according to the Allergy/Asthma Information Association. Common airborne allergens in the air include pollen, mould, dust and animal dander. Hay fever or seasonal allergic rhinitis, brought on by ragweed pollen, affects between two and 20 percent of North Americans. Anaphylaxis is a serious allergic reaction that can be life-threatening; about one to two percent of Canadians live with the risk of an anaphylactic reaction. The most common cause of anaphylaxis is food, such as peanuts, eggs and seafood, but insect stings, latex or exercise can also cause a reaction.

Allergy causes Allergies tend to run in families, and people who have one allergic trigger are more likely to have more than one. Certain conditions, such as asthma, sensitive skin and lung conditions, can predispose a person to have allergic reactions. Exposure to other things, such as smoke and air pollution, can worsen allergy symptoms.

Allergy symptoms The body’s reaction to the allergen causes the symptoms, such as runny nose, sneezing and itchy watery eyes. Symptoms of anaphylactic shock are much more serious and can develop quickly: they may include a rapid heartbeat, difficulty breathing and shock when blood pressure falls.

Allergy diagnosis/tests Talk to your doctor who will ask you about your signs and symptoms, examine you to determine if you have an allergy and conduct allergy testing:

Skin tests You may be referred to an allergy specialist for a skin test, where your skin is pricked and exposed to tiny amounts of the proteins from potential allergens. If you’re allergic to them, you’ll develop swelling or redness on the test spot on your skin. The allergist may also inject a small amount of an allergen into your skin to measure your sensitivity to a particular allergen. A patch test, where allergens are taped to your skin for 48 hours, may be helpful for diagnosing a food or mould allergy.

Blood tests These can help by measuring the amount of immunoglobulin (Ig) E antibodies to a specific allergen in the blood.

Elimination For food allergies, your doctor may propose that you try an elimination diet where you remove the foods that may be causing symptoms from your diet for several weeks and then slowly re-introduce them one at a time while watching for symptoms of an allergic reaction. If you have a positive result, you’ve reacted to a substance and may be allergic to it.

In the event that your physician suspects your symptoms are not due to an allergy, you may need medical tests to rule out other health issues.

Allergy treatment Most allergies can be controlled by avoiding what triggers them or by taking antihistamines or other medications to prevent an adverse reaction.

Antihistamines are over-the-counter medications that can help reduce allergy symptoms, including itchiness, sneezing and watery eyes. Non-sedating antihistamines may be less likely to cause tiredness or dry mouth: however, they may require a prescription.

Decongestants are available in pills, nose sprays and nose drops, and are effective for relieving the stuffy nose caused by allergies. Use with caution as these medications may increase blood pressure. If you have concerns, consult with your doctor before using them.

Epi-pens are used as treatment for people with anaphylaxis. People who are at risk of an anaphylactic reaction are advised to carry two epinephrine injectors at all times.

Allergy shots, also called immunotherapy, contain small amounts of allergens, which are administered on a regular schedule so that the body becomes naturalized to an allergen and no longer reacts to it.

Allergy prevention Even if you are treating your allergies, it’s a good idea to avoid your triggers, such as foods, insects, outdoor allergies or stress. If you’re not sure what’s causing them specifically, keep an allergy diary to record when your symptoms worsen, what you’re doing when this happens and then show it to your doctor to help pinpoint the triggers. Getting allergy shots (immunotherapy) can prevent allergic reactions.

More info from Chatelaine
How to allergy-proof your home

Outside resources
Allergy/Asthma Information Association

Allergy Canada