A food allergy is when your body’s immune system reacts to a food protein because it has mistaken that food protein as a threat. Symptoms can range from mild to life-threatening.
Food allergy is sometimes confused with food intolerance. Food allergies involve your immune system and can be lifethreatening. An intolerance is when your body has trouble digesting a food. It can make you feel badly, usually with an upset stomach, but it is not life-threatening. The most common intolerance is to lactose—which is a natural sugar found in milk.