Selenium disulfide lotion varies in use due to the different diseases it treats. Selenium disulfide lotion is mainly used for treating dandruff, combating seborrhea, seborrheic dermatitis of the scalp and lichen planus. To treat dandruff and seborrheic dermatitis of the scalp with selenium disulfide lotion, first wash the hair and scalp with soap, then take 5~10 grams of the liquid on the wet hair and scalp, and gently knead it until it foams. Wait for 3~5 minutes, then rinse with warm water and repeat if necessary. Use 2 times a week, a course of treatment in 2~4 weeks, severe symptoms can be added 1~2 courses of treatment. When using selenium disulfide lotion to treat lichen planus, first clean the affected area, and then according to the size of the affected area appropriate amount of liquid coated, generally 10~30 grams coated evenly, and then wait for 10~30 minutes, rinse with warm water. Used 2 times a week, a course of treatment in 2 ~ 4 weeks, serious symptoms can be added 1 ~ 2 courses. The specific dosage of the drug should be used according to the doctor’s instructions. Patients using selenium disulfide lotion may experience adverse reactions such as contact dermatitis, dry hair or scalp, and hair discoloration. It is contraindicated when the patient has inflammation, vesicles and oozing areas of the skin, and is contraindicated in the external genital area. Precautions: This product is for external use only and cannot be taken internally; it should not be used within two days after hair dyeing or perming; the scalp should be completely rinsed after using the drug to avoid decoloration; avoid contact with the eyes and other mucous membranes; it should be shaken well before use, and the cap of the bottle should be tightened after use. When patients need to use selenium disulfide lotion, it is recommended to use under the guidance of a doctor.