Melanosis, also known as melanosis, is a group of skin diseases characterized by diffuse pigmentation mainly on the face and neck, and whether melanosis can restore the previous skin is related to the cause of the disease. If the cause is clear, active treatment of the cause can generally be restored, but the length of recovery time varies from person to person. If the cause of melanosis is not clear, then targeted treatment is not possible, and therefore the skin is generally difficult to restore to normal. Most patients have a history of exposure to photosensitive substances, which can also be caused by topical application of poor quality cosmetics. Workers who have been exposed to lead substances for a long time and those who work around tar can also suffer from black skin changes due to the deposition of tar volatile gases on the skin, which usually disappears within a few weeks when removed from the exposure environment. Patients should also avoid contact with suspected allergens and take measures such as avoiding light in daily life, pay attention to sun protection especially in spring and summer when it is advisable to use sunscreen, avoid using poor quality cosmetics, after the above treatment for the cause can generally restore the previous skin, but may take longer. Some drugs can also cause melanosis, such as hydroxychloroquine, tetracycline, isotretinoin, etc. can appear pigmentation adverse reactions, usually drug-induced melanosis can slowly recover after discontinuation of the drug, the length of this process varies from person to person.