As allergens (allergens) of many substances, according to the route of entry into the following categories: 1, inhalants: house dust, pollen, mold, mites, feathers, animal dander, cotton wool, cosmetics, etc.. 2, ingested substances: such as eggs, milk, fish, wheat, etc. Salicylic acid, barbiturate, sulfonamide, etc. in drugs. 3.Injectables: there are serums and antibiotics, etc. Intravenous injection is faster and more severe than subcutaneous injection reaction. 4, contact material: topical drugs, paints, plants, cosmetics, etc., often caused by allergies to contact dermatitis. 5, bacteria: Some allergic reactions are caused by foci, the main foci are tonsils, nasal. Sinus, teeth and periodontal tissue, vagina, prostate, gallbladder, etc. 6, endogenous allergens (allergens): the body’s internal self-generated allergens, such as certain metabolites, or denatured tissue proteins, etc..