Food intolerance refers to a physical response to a food or food additive that is not an allergic reaction. It differs from a food allergy in that it does not involve the immune system and it is much more common.

Food intolerances are often mistaken as food allergies. Some common food intolerances include food additives like MSG and sulfites; lactose; gluten; food poisoning; histamine toxicity; and ulcers and cancers of the digestive tract. Food intolerances do not usually cause as severe a reaction as food allergies, but they can cause nausea, vomiting, painful cramping, and diarrhea.