Salicylic acid needs to be applied for 2 to 3 minutes or 3 to 5 minutes at a time depending on its concentration and the user’s own skin type, tolerance, and severity of the condition. Salicylic acid needs to be used on a case-by-case basis, and no generalizations can be made. Salicylic acid is a fat-soluble organic acid, can stimulate the skin, mucous membranes, because it can react with the proteins in the tissues of the body, so it has a corrosive effect, and it can make the cornea proliferate and then peel off. Many people plagued by acne choose to buy skin care products containing salicylic acid to improve their skin. Generally speaking, depending on the concentration of salicylic acid in different skin care products, as well as the user’s own skin condition and tolerance, each time you need to leave it on for anywhere from 3 to 5 minutes. Before using salicylic acid products for the first time, it is necessary to test them by applying them behind the ears for about 5 minutes to see if they cause any allergies. If there is no discomfort, after the face is clean, you can put the salicylic acid products on the face, if the first time to use, acne is not too serious or intolerance of patients can be applied for 2 to 3 minutes, if the acne is more serious or has established tolerance can be applied for about 5 minutes. After applying, simply wash with water and apply moisturizing products. Salicylic acid products irritation, contraindications are not clear, there may be irritation or contact dermatitis, large area absorption can have systemic toxicity symptoms such as dizziness, confusion. It is recommended to use under the guidance of a doctor after a formal dermatology consultation, and not blindly use on their own.