The antigenic substances that trigger outbreaks of allergic diseases are medically referred to as allergens. Since there are thousands of species, each allergic patient may be caused by a different antigenic substance. Nowadays, common allergens are clinically classified into the following categories: 1. Allergenic substances that cause allergy through breathing – inhalation allergens: such as pollen, willow wool, dust, insect mites, cold air, animal dander, oil smoke, various spices, car exhaust, gas, cigarettes, etc. 2, allergic allergens through diet – ingested allergens: such as seafood, fish and shrimp, allogeneic proteins, dairy products, soy products, chicken and duck, beef and mutton, rice, flour, sesame oil, toon, onion, ginger, garlic, animal fat, alcohol, as well as peaches, pears and other fruits, dried fruits, vegetables, preserves, some antibacterial agents The anti-inflammatory drugs, anti-inflammatory drugs, antipyretic and analgesic drugs, etc. 3, by touching the allergic antigenic substances – contact allergens: such as cosmetics, hair dyes, paints, cold air, hot air, ultraviolet light, radiation, cosmetics, shampoo, detergent, hair dye, soap, chemical fiber products, plastic, metal jewelry (necklaces, bracelets, watch bands, rings, earrings), bacteria, mold, viruses, parasites, etc. viruses, parasites, etc. 4, other allergens: such as injection of pharmaceutical penicillin, streptomycin, xenogeneic serum, etc., mental tension, work stress, etc., and many patients simply can not identify the specific allergens.