The skin becomes itchy with air masses after scraping on the one hand is due to skin damage caused by gua sha, on the other hand is due to allergic reaction. 1. skin damage: when scraping gua sha, local skin may appear mechanical damage, even with subcutaneous bleeding. Mechanical damage often secondary inflammatory reaction, stimulate peripheral tissue peripheral nerves, inflammatory reaction and local skin bruising reaction will make the patient self-conscious itchy. 2. Allergic reaction: in Gua Sha, usually need to be in the skin coated with some drugs and skin care products, and then repeatedly rubbed with the Gua Sha board, part of the patient will be coated with the material or scraping piece of the material to produce an allergic reaction, and thus the skin itching as well as the air masses. Therefore, if the skin becomes itchy after scraping Gua Sha, you need to go to the hospital in time to seek professional doctor’s help, and it is not recommended to scrape Gua Sha for a long time or frequently.