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Severe allergy triggers

A severe allergic reaction is a reaction your body has to a particular trigger or ‘allergen’.

The most common triggers that can lead to a severe allergic reaction include:

Video: Triggers of a severe allergic reaction

Learn about the most common triggers of a severe allergic reaction and useful tips for avoiding your triggers.

Food Triggers

Food Triggers

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Health Canada and the Canadian Food Inspection Agency (CFIA) have identified ten substances that are most frequently associated with food allergies and allergic-type reactions. These substances are often referred to as the ten priority food allergens.

The top ten food allergens in Canada include:
  • Peanuts
  • Eggs
  • Milk
  • Tree Nuts
  • Wheat
  • Soy
  • Sesame Seed
  • Seafood (e.g., fish, crustaceans and shellfish)
  • Sulphites
  • Mustard

Health Canada and the CFIA recommend these items be included on all product labels when used as an ingredient or part of an ingredient.

People have been known to outgrow allergies to milk, soy and eggs after childhood. But peanut, tree nut and shellfish allergies tend to be lifelong.

Visit the Health Canada website to find patient brochures on food allergies.

Insect Stings

Insect Stings

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The insects most likely to trigger severe allergic reactions belong to the Hymenoptera order of insects, also known as stinging insects. Stinging insects inject venom when they sting the skin. This venom can cause a severe allergic reaction.

Stinging insects include:

  • Bees
  • Wasps
  • Yellow jackets
  • Hornets
  • Ants, including the fire ant

Biting insects (e.g., mosquitoes and black flies) may also trigger severe allergic reactions.

It is important to note that insect repellent does not protect against stinging insects.

Latex Triggers

Latex Allergy

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A latex allergy is an allergic sensitivity to the proteins in natural rubber latex (NRL). This reaction affects several systems throughout the body and often worsens with each exposure, potentially resulting in a severe allergic reaction.

Unlike synthetic latex, which rarely causes allergic reactions, NRL comes from the milky sap of rubber trees. Using various processing methods, NRL is used alone or in combination with other materials to make thousands of products including:

  • Gloves
  • Condoms, diaphragms, and dental dams
  • Adhesive bandages
  • Medical equipment such as stethoscopes, blood pressure cuffs, and tourniquets
  • Elastic
  • Spandex
  • Party balloons

It is important to recognize that there is an association between reactions to latex and some foods. If you are allergic to latex, you may also notice a reaction to banana, avocado, kiwi, or chestnut. Tell your healthcare provider about any bad reactions you may have had to fruits and vegetables.

Medication Triggers


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Both prescription and non-prescription drugs may cause an allergic reaction.

Medications that most often cause a severe allergic reaction include:

  • Penicillin and related antibiotics are the most common cause of drug allergies. Other allergy-causing drugs include:
    • Aspirin and non-steroidal anti-inflammatory drugs
    • Sulfa antibiotics
    • Insulin, especially those from animal sources
    • Anticonvulsants
    • Local anaesthetics such as Novocain
Exercise-Induced Anaphylaxis

Exercise-Induced Anaphylaxis

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Some people experience an allergic reaction after they exercise. A severe reaction is known as exercise-induced anaphylaxis and is a form of physical allergy.

Why exercise causes a reaction is unknown. However, it appears that some medications [such as aspirin or non-steroidal anti-inflammatory drugs (NSAIDs)] or food consumed before and after exercise are factors that have been associated with experiencing exercise-induced anaphylaxis.

The reaction usually starts with skin symptoms such as itchiness, redness, or hives. If left untreated, it can lead to more serious gastrointestinal symptoms as well as swelling of the throat.

Idiopathic Anaphylaxis

Unknown Causes: Idiopathic Anaphylaxis

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Sometimes a severe allergic reaction can occur without a known cause. This is called idiopathic anaphylaxis.

As with other types of severe allergic reactions, symptoms of idiopathic anaphylaxis include hives or skin swelling, wheezing, difficulty breathing, nausea, light-headedness, and fainting. However, most people don’t experience all of these symptoms at once.

A healthcare provider should try to rule out all other causes before making the diagnosis of idiopathic anaphylaxis.

Your trigger may have different names.

Download the MyEpiPen Canada app to check the different names for allergy triggers.