To prevent melasma, it is important to take strict sun protection and prevent sun exposure, and to inform that the course of treatment is relatively long and requires persistent medication for improvement. After the appearance of melasma, you should avoid the external use of irritating cosmetics and keep your mood happy, and give topical application of 3% hydroquinone cream and 0.05% retinoic acid cream in time. It is also necessary to apply oral vitamin C capsules, Liu Wei Di Huang Wan or Jin Kui Ren Qi Wan as a preventive medicine. After the appearance of melasma, you can also actively apply 20% glycolic acid fruit acid for application treatment as early as possible, which usually needs to be treated once a month, and usually takes about 3 months of treatment.