Topical retinoids have the ability to regulate epidermal keratinocyte differentiation, improve follicular sebaceous duct keratinization, dissolve microcomedema and acne, and have anti-inflammatory effects. Topical retinoids are the first-line drugs for mild acne, the first-line drugs for moderate acne, and the drugs of choice for acne maintenance treatment. Currently, commonly used topical retinoids include first-generation retinoids such as 0.025% to 0.1% all-trans retinoic acid creams or gels and isotretinoin gels, and third-generation retinoids such as 0.1% adapalene gel. Adapalene is better than all-trans retinoic acid and isotretinoin in terms of tolerability and safety. It is more effective than all-trans retinoic acid in non-inflammatory lesions and can be used as the first-line choice of topical retinoids for acne. Topical retinoids often cause mild skin irritation, such as local erythema, flaking, tightness and burning sensation, which may gradually disappear with prolonged use. It is recommended to be used at low concentrations or in small areas, once a night, away from light. Benzoyl peroxide is a peroxide that slowly releases neo-oxygen and benzoic acid after topical application, which has the effect of killing Propionibacterium acnes, dissolving acne and astringent. It can be formulated as a lotion, emulsion or gel in different concentrations of 2.5%, 5% and 10%. A few sensitive skins may experience mild irritation and it is recommended that sensitive skins start with a low concentration and a small trial. Benzoyl peroxide can reduce the occurrence of drug resistance in Propionibacterium acnes and can be used as one of the topical antibacterial drugs of choice for inflammatory acne if tolerated by the patient. Topical antibiotics Commonly used topical antibiotics include erythromycin, lincomycin and its derivatives clindamycin, chloramphenicol or clindamycin, etc., prepared with ethanol or propylene glycol at a concentration of 1% to 2%, which are more effective. 1% chloramphenicol phosphate brew solution is a water-soluble emulsion without oil and ethanol, suitable for acne patients with dry and sensitive skin. In recent years, it has been found that topical fusidic acid cream has good killing effect and anti-inflammatory activity on Propionibacterium acnes, and it has no cross-resistance with other antibiotics, so it can also be used as one of the topical antibiotics for acne treatment. Since topical antibiotics are likely to induce resistance in Propionibacterium acnes, they are not recommended for use alone, and are recommended to be used in combination with benzoyl peroxide or topical retinoids. Disulfide Sun 2.5% Disulfide Sun lotion has the effect of inhibiting fungi, parasites and bacteria, and can reduce the free fatty acid content of the skin. After cleansing the skin, apply the solution slightly diluted evenly on the part of seborrhea, and wash with water after 3~5min. Other topical medications 5% to 10% sulfur lotion and 5% to 10% salicylic acid cream or gel can be used for acne treatment because they inhibit Propionibacterium acnes and have a slight exfoliating and antibacterial effect. Topical antibacterial and anti-inflammatory medications are generally recommended for spot application on lesions, while topical retinoids are recommended for simultaneous application on lesions and acne-prone areas due to their anti-microcomedogenic effects. Treatment usually takes 8 to 12 weeks or longer.