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Food allergies

Food allergies


Food allergies occur when the body’s immune system reacts to a protein in food. It is estimated that six per cent to eight per cent of children and two per cent to four per cent of adults have a food allergy.

Food allergy symptoms

The symptoms of a food allergy vary, but they can include:

  • breathing problems and wheezing
  • hives (raised, red, itchy bumps)
  • itching of the nose, mouth, throat, skin
  • swelling around the face, mouth or throat
  • a sudden drop in blood pressure
  • shock.

Common causes of food allergies

In Canada, the most common foods that cause allergies are:

Difference between a food allergy and food intolerance

Many people may believe they have a food allergy when they may only have a food intolerance.

A food allergy involves the body’s immune system reacting to a protein in a food. However, a food intolerance occurs when the body's digestive system cannot handle a specific food very well. Symptoms of food intolerance include gas, bloating, vomiting and diarrhea. 

One common substance for food intolerance is lactose, a sugar found in dairy products. A person is usually intolerant to lactose if they lack lactase, the enzyme that breaks down the sugar in the intestines.

An allergic reaction to a food usually occurs quite quickly: symptoms can appear within minutes. With food intolerance, symptoms can be delayed, sometimes appearing hours after a person eats the food. Symptoms also depend on the amount of the food the person eats.

A person with a food intolerance can usually tolerate small amounts of the food. An individual with a true food allergy must completely avoid the foods that cause the reaction.

Managing food allergies

When a child is diagnosed with a food allergy, there are many things to consider to manage it properly: from reading food product labels at the grocery store and preparing family meals to eating out or sending your child to their friend’s birthday party. This may seem difficult at first, but following some routine safety steps will soon become second nature for you and your child. It will keep your child safe from harm without restricting their enjoyment of food at home or while travelling.

Just for Kids

You cannot always be there to see what your child eats. Share these child-fr​iendly tips about food allergies​ with your child to help them learn more.


Reviewed by:
Elly Berger, BA, MD, FRCPC, FAAP, MHPE