•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)
•Insect bites or stings
•Exposure to heat, cold, or sunshine.