Acne is a chronic inflammatory skin disease concerning the sebaceous glands, with a prevalence of 70% to 87%, and has a psychological and social impact on adolescents that exceeds that of asthma and epilepsy. Local treatment of acne] Local washing: Care should be taken to wash the face with water to remove the oil and the mixture of dander and bacteria from the skin surface. However, excessive washing should not be done. Do not squeeze or scratch the acne with your hands. In addition, avoid using oily, fatty, powdered skin care cosmetics and ointments and creams containing hormonal ingredients. (1) 0.025% to 0.1% retinoic acid (all-trans retinoic acid) cream or gel: This agent can regulate the differentiation of epidermal keratin-forming cells and make acne dissolve and be discharged. The skin is mildly irritated at the beginning of 5~12 days, such as local flushing, flaking and tightness or burning sensation, but it can gradually disappear. Therefore, it should be applied once a day at night starting from low concentration to avoid increasing drug irritation after light exposure, and topical application once a week after symptoms improve. (2) 13-cis-retinoic acid gel: regulates the differentiation of epidermal keratin-forming cells and reduces sebum secretion, once or twice daily. (3) Third-generation retinoids: 0.1% adapalene gel, once a night, has good efficacy in treating mild and moderate acne. 0.1% tazarotene cream or gel, used once every other night to reduce local irritation. 2. Benzoyl peroxide: This drug is a peroxide, which can slowly release neo-oxygen and benzoic acid after topical application, which can kill Propionibacterium acnes, dissolve acne and have an astringent effect. It can be formulated into 2.5%, 5% and 10% different concentrations of lotion, emulsion or gel, and should be used from low concentrations. Gel containing 5% benzoyl peroxide and 3% erythromycin can improve the therapeutic effect. 3, antibiotics: erythromycin, chloramphenicol or clindamycin, prepared with alcohol or propylene glycol at 1% to 2% concentration, is more effective. 1% chloramphenicol phosphate solution is a water-soluble lotion that does not contain oil and alcohol and is suitable for acne patients with dry and sensitive skin. 1% chloramphenicol hydrochloride solution is equally effective. 4. Azelaic acid: It can reduce the flora on the skin surface, in the hair follicles and sebaceous glands, especially has an inhibitory effect on Propionibacterium acnes and acne lysis effect, and is effective for different types of acne. Can be formulated into 15%-20% cream for external use, the side effects of local erythema and tingling. 5, selenium disulfide: 2.5% selenium disulfide lotion has the effect of inhibiting fungi, parasites and bacteria, and can reduce the free fatty acid content of the skin. Use for clean skin, slightly diluted with the solution, evenly coated in the seborrhea obvious parts, about 20min and then wash with water. 6%~10% sulfur lotion: It has the function of regulating the differentiation of keratin-forming cells and reducing the free fatty acid of the skin, and also has a certain inhibitory effect on Propionibacterium acnes.