Allergens are characterized by proteins (not fat or carbohydrate) with 10-70 kD glycoproteins that are heat-resistant and acid-stable. Major allergenic foods in children are milk, egg, soy, wheat, tree nuts, and peanuts; among adults, peanuts, tree nuts, shellfish, and fish are most likely to be the culprits. Cow’s milk alone has over 30 proteins which may be antigenic (Casein, whey, lactoalbumin, etc…). Hen’s egg also has a large number of proteins (albumin, meringue, etc..). The patient also needs to be aware of other foods which contain even minimal allergic ingredients.