Food Allergies vs. Food Intolerances: Knowing the Difference

Food allergies and food intolerances both cause unpleasant symptoms after eating, but they involve fundamentally different biological mechanisms. Understanding the distinction is important for safety and management. A food allergy involves the immune system. When someone with a food allergy eats the trigger food, their immune system overreacts, producing IgE antibodies. This can cause symptoms ranging from hives, swelling, and vomiting to life-threatening anaphylaxis. Canada\'s most common food allergens include peanuts, tree nuts, milk, eggs, wheat, soy, fish, shellfish, sesame, and mustard. A food intolerance does not involve the immune system. It is typically a digestive issue - for example, lactose intolerance occurs when the body lacks the enzyme to digest lactose. Symptoms include bloating, gas, diarrhea, and stomach cramps. While uncomfortable, food intolerances are not life-threatening. Key differences: food allergies can cause anaphylaxis (food intolerances cannot), even tiny amounts can trigger allergic reactions, while intolerances are usually dose-dependent, and food allergy testing involves skin prick tests or blood tests (IgE), while intolerances are diagnosed through elimination diets. If you suspect a food allergy, consult your physician for proper testing. Anaphylaxis requires an epinephrine auto-injector (EpiPen). *This article is for informational purposes only.*

This article is for informational purposes only and does not constitute medical advice. Content reviewed by licensed Canadian physicians. Last updated February 2026.