Cosmetics in direct contact with human body surface during use may cause serious consequences including skin reactions if the product has problems. Therefore, a number of tests must be carried out to ensure the safety of cosmetics before they are put on the market. Among them, patch test is a commonly used cosmetic safety test, which can detect the potential possibility of adverse skin reactions caused by the tested substance.

Common types of skin patch test include closed patch test, repeated open patch test and repeated injury patch test.

Generally, the skin sealing patch test is widely used in cosmetics.

Under special circumstances, such as freckle removing cosmetics and powdered (such as powder and foundation make-up) sunscreen cosmetics, when the human skin patch test shows irritating results or the results are difficult to judge, the skin repeated open application test should be increased. The skin repeatability open test is also applicable to rinsing products, hair dyes, hair removal products, etc.