1.Inhalation allergens: dust mites. Spring and summer pollen. Fungi. Animal dander. Cockroaches, etc. 2, food allergens: a variety of food, seafood, fruit, nuts are common. 3, contact allergens: metal. Hair dyes. Cosmetics, etc. 4, drug allergens: penicillin. Cephalosporins. Sulfonamides, insulin, etc. 5, injected allergens: insects, mosquito bites, etc..