Melanosis may be caused by physiological factors such as ultraviolet radiation and does not require the application of ointment. It may also be caused by post-inflammatory hyperpigmentation and melanosis. Post-inflammatory hyperpigmentation can be treated by applying azelaic acid ointment, and melanosis can be treated by applying hydroquinone cream and other medications. 1. Physiological factors: ultraviolet radiation can lead to melanocyte activation, resulting in melanin precipitation, need to do a good job of sunscreen, go out and need to apply sunscreen or umbrellas, with the passage of time, the pigment particles are metabolized and absorbed, and most of them will disappear on their own without the need to apply ointment. 2. Post-inflammatory hyperpigmentation: patients with post-inflammatory hyperpigmentation can apply azelaic acid cream, niacinamide gel for treatment, which can inhibit the proliferation of melanocytes and reduce the phenomenon of melanin deposition, and can also apply arbutin cream, hydroquinone cream for treatment. 3. Melanosis: patients with melanosis can apply hydroquinone cream, compound arbutin ointment to treat, which can aggravate the inflammation subside, improve the phenomenon of melanosis, and if necessary, can also apply dexamethasone ointment, hydrocortisone butyrate ointment to anti-inflammatory. Melanosis has more causes, after excluding physiological factors, should be admitted to the hospital for examination, according to the cause of the treatment.