Different allergy types = different reactions

Allergies manifest as a range of symptoms: they can be unnoticeable, make you miserable, or pose a life-threatening danger.


Dominique Vanier
Dominique Vanier

18 April 2016


An allergy is an abnormal immune response to a substance that either enters or contacts the body. Allergies can impact various systems in the body, affecting the skin, gastrointestinal tract, respiratory tract, cardiovascular system, or all of them concurrently.

When the body encounters an offending allergen such as pollen, milk, or peanuts, it mistakes the allergen as an “invader,” overreacts, and mounts an attack. This is also known as an IgE-mediated hypersensitivity reaction, characterized by histamine release and unpleasant symptoms.

As every immune response is different, so too is the severity of allergy symptoms. While the same class of antibodies mediates each allergic reaction, how these antibodies lead to allergic symptoms changes from person to person.

Types of allergies

The most common types of allergies include:

  • Seasonal allergies. Also referred to as hay fever or allergic rhinitis, seasonal allergies are typically a reaction to high levels of pollen released in the springtime and ragweed in the fall. Symptoms are usually limited to sneezing, a stuffy nose, and itchy, watery eyes.
  • Food allergies. Food allergies are due to an overreaction to a protein or sugar molecule found on the surface of various foods. There are 10 priority food allergens outlined by Health Canada that are most commonly associated with allergic-type reactions, which include: eggs, milk, wheat, peanuts, tree nuts, seafood, mustard, sesame, soy, and sulphites. Symptoms of food allergies can range from mild to severe, and may include: mouth tingling or itching; swelling of the lips, face, or tongue; nausea, vomiting, and diarrhea; and potentially anaphylaxis.
  • Pet allergies. Unfortunately for pet owners, dogs and cats are the most common causes of pet allergies. These allergies are in fact a reaction to a protein found in the animal’s saliva, urine, or on their skin. Symptoms of pet allergies are typically confined to nasal passage and sinuses, and may include: watery, itchy eyes; stuffy nose; sinus pain; chest tightness and wheezing; and a skin rash.
  • Environmental allergies. Environmental triggers including mould, dust mites, and outdoor plants can be the source of allergies. Symptoms often present similarly to pet allergies.
  • Drug allergies. Drug allergies are common, and may be mild or severe in nature. If an allergy to a medication is suspected, it is imperative to notify and work with your health care practitioner. Signs and symptoms of drug allergies depend on the drug and individual, and typically occur soon after taking the drug. These may include: hives; rash; itchy skin or eyes; injection site reactions; and potentially anaphylaxis.

While most allergies are non-life threatening, it is important to recognize the signs and symptoms seen in severe allergic reactions, also known as anaphylaxis. When the allergy leads to systemic symptoms including difficulty breathing, wheezing, difficulty swallowing, a large drop in blood pressure, and a fast pulse, medical attention should be sought immediately. Many allergy types have the potential of causing anaphylactic reactions.

What can be done

With mild allergies, several approaches can be taken to ease an allergic response:

  • If the source of the allergy is known, avoiding exposure to the allergen is often enough to keep symptoms at bay.
  • Purchase a HEPA filter. A high-efficiency particulate air filter removes 99% of small allergens in the home by trapping dust, dirt, and other air immunogens. HEPA filters can help reduce allergic responses to pets and pollen that has found its way inside the home.
  • Get symptomatic relief. Allergy Relief is an effective product that can reduce sneezing, an itchy nose, and burning eyes commonly caused by allergic rhinitis.
  • Try an elimination diet. If it is unclear which food is causing an allergic reaction, an elimination diet can help narrow down food culprits.
  • Re-educate your immune system. A new therapy called Sublingual Immunotherapy (SLIT) gradually exposures the immune system to the offending allergen. Under strict medical supervision, this technique can decrease the severity of the allergy over time. In a randomized controlled study, clinical desensitization to peanuts was observed in 70 per cent of participants.