Foods (commonly eggs, shellfish, nuts, berries, dyes, or other additives)
•Drugs (any drug can touch off an allergic reaction, although allergies to penicillin, sulfa, and aspirin are especially common)
•Pollens and plants (nettles, poison ivy, poison oak, and so on)
Drug treatment is typically in the form of Antihistamines such as
diphenhydramine, hydroxyzine,
cetirizine. Non-sedating ones are Loratidine, though it will require a day or two to build up to effective levels.