Food allergy and food intolerance are used interchangeably in everyday conversation, but the difference matters. A true allergy can trigger anaphylaxis from a trace amount of food, while an intolerance almost never does.
According to Mayo Clinic guidance, a food allergy involves the immune system and can be triggered by even small amounts of the offending food, while an intolerance mainly affects the digestive system and typically produces milder symptoms.
Roughly 33 million Americans have at least one food allergy, according to Food Allergy Research & Education. Here are eight practical differences to help you tell an allergy from an intolerance.
1. Immune system vs. digestive system
A food allergy is an immune reaction. The body mistakes a food protein for a threat and produces immunoglobulin E (IgE) antibodies, which trigger the release of histamine and other chemicals. An intolerance is a digestive problem, often caused by a missing enzyme.
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2. A trace amount vs. a small serving
Even a small amount of an allergen can trigger symptoms, sometimes severe or life-threatening. With intolerance, a small portion of the offending food is often tolerated without a reaction.
3. Speed of onset
Allergic symptoms usually appear within 30 minutes to two hours of eating the food, and often start within minutes. Intolerance symptoms build more slowly, typically over several hours.
4. Severity and anaphylaxis risk
Allergies carry the risk of anaphylaxis, a whole-body reaction that can cause breathing difficulty and a sudden drop in blood pressure. The American College of Allergy, Asthma & Immunology describes epinephrine as the first-line treatment for anaphylaxis, delivered by auto-injector. Food intolerance is not life-threatening.
5. What the symptoms look like
Allergy symptoms often affect several body systems at once, including the skin (hives, swelling), the airways (wheezing, throat tightness) and the gut (vomiting). Intolerance symptoms stay mostly in the digestive tract, with bloating, gas, diarrhea and cramps.
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6. Common triggers
Nine foods account for about 90 percent of allergic reactions in the United States. They are milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soy and sesame. Intolerance often traces to lactose, sulfites used to preserve dried fruit and wine, other food additives, or irritable bowel syndrome.
7. Whether it usually lasts for life
Peanut, tree nut and shellfish allergies tend to persist into adulthood, though some childhood allergies to milk and eggs can fade. Many intolerances are managed by portion control or an enzyme supplement, such as lactase for lactose intolerance.
8. How each is diagnosed
A food allergy is confirmed with a skin-prick test or a blood test measuring specific IgE antibodies, sometimes followed by a supervised oral food challenge. Intolerance is typically identified through a food diary and an elimination diet, where the suspected food is removed and then reintroduced.
When to see a doctor
If you get hives, swelling, wheezing or lightheadedness within two hours of eating, treat it as a possible allergy and see an allergist. Only formal allergy testing can distinguish a true IgE-mediated allergy from an intolerance, and that distinction is what decides whether you need to carry an epinephrine auto-injector such as EpiPen, Auvi-Q or Adrenaclick.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.