In order to prevent the occurrence of cosmetic allergies, especially in allergic people, it is recommended to conduct a skin patch experiment by yourself before using new cosmetics. The patch experiment method is simple: first put the cosmetics to be used on four layers of 1 cm2 gauze, paste it on the inside of the left forearm, while using saline on the inside of the right forearm as a control, and cover the two pieces of gauze with a plastic film of wax paper slightly larger than the gauze. Finally, the gauze was fixed with adhesive tape, and the gauze was removed when 24-48 hours old. If erythema, papule, blister with itching appeared on the patch of skin, it was positive, or less than 24 hours after patching, the skin had reacted and the experiment should be terminated immediately. If the above situation indicates an allergy to such cosmetics, the cosmetics should not be used; if the skin does not react, it means that the cosmetics may not be allergic and can be used. Usually we have to be careful when buying cosmetics, it is best to choose a well-known brand and check the outer packaging of the product carefully. It is best to choose a well-known brand and check the packaging of the product carefully. The outer packaging of a legitimate cosmetic should be marked with the health license number, production license number and the manufacturer’s executive standard number to determine whether the nature, composition and use of the cosmetic is suitable for you before purchasing it. At the same time, it is important to keep the invoices, packaging, and instructions to help defend your rights in case of injury. At the same time, it is important to know that there are no regulations that clearly define the division of responsibility and compensation for cosmetic allergies. Merchants generally make the promise that within 7 days of purchase, if an allergic reaction occurs, consumers with patch test test results, the consumer can be returned for the procedures.