Food Allergy or Intolerance?


In North America, approximately 5% of children and 1-2% of adults have allergies to food, although many more individuals believe that they suffer from food allergies and restrict their diet accordingly.

Some of these individuals have food intolerances; others may have food aversions, and some may have potentially life threatening food allergies.

So how do you differentiate food allergies from food intolerance?

A food allergy is caused by a reaction of the immune system to a food protein.

Even very small amounts of food can be dangerous to people with severe allergies. Food intolerance is any food reaction not caused by the immune system.

The best known is lactose intolerance, which means that a person cannot digest milk sugar.

Usually the symptoms relate to the gastrointestinal tract and although they may be unpleasant, they are not life threatening.

The most common allergy-causing foods include:

  • milk, eggs, peanuts, tree nuts, soy, fish, and seafood.
  • Milk, soy, and egg allergy a • re usually outgrown by school age
  • Peanut, tree nut, fish, and seafood allergies usually persist indefinitely

Symptoms of food allergies

Allergic reactions to foods typically begin within 30 minutes of eating the food.

  • Itching and burning of the mouth
  • Hives (an itchy, raised rash and swelling) or skin redness
  • Stomach pain, vomiting, diarrhea
  • Difficulty breathing, swallowing or speaking
  • Cough
  • Hoarse voice
  • A drop in blood pressure with weakness, loss of consciousness or confusion

How are food allergies diagnosed?

If you suspect your child has a food allergy, you should speak to your family doctor or pediatrician. If the doctor agrees, he will refer you to an allergist, who will take a history of the reaction, examine your child, and usually do skin tests and/or a blood test. If the diagnosis is still not clear, a food challenge may be necessary to determine if your child is truly allergic to the food.

How to avoid foods that cause an allergic reaction

  • Read all labels carefully
  • Know the different product names
  • Teach your children to eat only things from home, or to ask a responsible adult if the food is safe
  • Inform your friends and relatives and when eating out, tell restaurant staff
  • Be aware of potential sites for cross contamination (e.g. shared utensils at restaurants).

What to do if your child eats a food he is allergic to?

For mild hives or swelling, watch your child closely and consider giving an antihistamine (e.g. Benadryl).

For severe swelling, hives or any internal symptoms, the best medication is an injection of epinephrine (adrenaline). If required, your doctor will prescribe an Epi-Pen or Twinject, devices that allow for
self administration of adrenaline.

If your child has a serious allergic reaction, he must be taken to the hospital immediately. Childrenprescribed adrenalin should carry it at all times!

Do children outgrow allergies?

Most children allergic to eggs and milk will outgrow their allergies by ages 3 to 5. A small number can outgrow allergies to nuts, fish and peanuts so it is important to have regular follow-ups with your allergist.

Where to get help?

The doctors and nurses at the Montreal Children’s Hospital Allergy Clinic are available for consultation.

Allergy and immunology

  • Room A 02.2227
  • 514-412-4040 (phone)
  • 514-412-4288 (fax)