Food allergy or hypersensitivity refers to an abnormal immunologic reaction in which the body's immune system produces an allergic antibody, called immunoglobulin E (IgE) antibody, to usually harmless foods, such as milk or egg protein, resulting in allergy symptoms such as wheezing, diarrhea or vomiting.

Food allergy is different from food intolerance. The term "food allergy" is sometimes used in a vague, all-encompassing way, muddying the waters for people who want to understand what a real...