1.Western medical treatment ①Treatment principle Melasma is a common disease, and its treatment mainly starts from inhibiting the activity and proliferation of melanocytes, preventing melanin formation and accelerating melanin degradation, etc. During and after treatment, all patients should avoid sun exposure, especially avoid peak UV radiation (10:00~14:00), and use broad-spectrum sunscreen: including UVA and UVB (choose sunscreen with SPF>30 and PA++ or above). 30 and PA+++ sunscreens). Apply sunscreen 20-30 minutes before going outside, outdoors, choose SPF> 30 and PA+++, indoors SPF> 20 and PA++, 3-4 times a day, 2mg per cm2. ② Systemic medication (1) Vitamin C: This drug can stop the oxidation process of melanin and inhibit melanin formation, the general dosage is 200mg,3 times/d. Vitamin C injection, 3g/time, weekly 2 times a week. (2) Vitamin E: This drug is a strong antioxidant, which reduces lipid peroxide and thus plays the role of scavenging oxygen free radicals, and is currently a more classic and effective drug, the general dosage is 100mg, 3 times / day. (3) Glutathione: It acts as a coenzyme or participating enzyme of antioxidant enzymes, reduces the antioxidant effect of unsaturated fatty acids and eliminates oxygen free radicals. (4) Traditional Chinese medicine: those with menstrual disorders and blood stagnation can take Prosperity Pill or Tao Hong Si Wu Tang; those with deficiency of kidney water and incandescent deficiency fire can take Liu Wei Di Huang Wan, Jin Kui Kidney Qi Wan, and Ah Gao Huang Jing Wan to nourish Yin and tonify kidney, harmonize Qi and blood, dredge liver qi, and activate blood circulation and remove blood stasis to treat chloasma. (3) Topical treatment Depigmentation agent (1) 3% hydroquinone cream, which mainly blocks the process from tyrosine to dopa catalyzed by tyrosinase to affect the synthesis of melanin, is often effective when applied continuously for several months. Its adverse effects sometimes cause irritant contact dermatitis, the irritation is related to the concentration of hydroquinone. In addition, there are 5% ~ 10% mercury ointment, 10% urea cream, 3% hydrogen peroxide, after application have varying degrees of efficacy, because the drugs are easy to oxidation in the air and sunlight, should be closed and stored away from light. (2) 0.l% retinoic acid, 5% hydroquinone, 0.1% dexamethasone in hydrophilic ointment, 2 times/d, topical application, also good therapeutic effect, retinoic acid has enhanced the epidermal penetration of hydroquinone and reduce the activity of melanocytes. (3) 20% azelaic acid cream, azelaic acid is a non-toxic non-teratogenic natural straight chain saturated dicarboxylic acid, is a competitive inhibitor of tyrosinase. (4) Arbutin: It is the active ingredient extracted from the plant bearberry. It can inhibit the activity of Tyra and is commonly used in 3% cream or ion introduction therapy. 2.Exfoliation therapy Fructic acid, i.e. hydroxyacetic acid revitalization treatment: it can accelerate skin renewal, reduce epidermal adhesion at low concentration, and cause epidermal relaxation at high concentration, remove pigmentation through epidermal damage and epidermal regeneration, generally with 10% preparation. (1) The combination of vitamin C and vitamin E is significantly more effective than using it alone, probably because VitC can recirculate VitE. (2) Taylor et al. treated 641 melasma patients with 0.05% vitamin A acid, 4.0% hydroquinone and 0.01% fluorescence for a total of 8 weeks. 26.1% and 70% of patients had complete pigmentation and 75% regression, respectively, and the adverse effects were mild and tolerable. (3) Lee et al. used a mixture of 2% linoleic acid, 0.05% betamethasone valerate and 2‰ lincomycin once a night for 6 weeks to treat melasma, and obtained good efficacy without obvious adverse effects. (4) Mentel used glucocorticoids in combination with retinoic acid and hydroquinone, which not only showed early effect, but also effectively inhibited the synthesis and secretion of melanocytes and reduced melanin production. (5) Kligman first proposed the “kligmancream” with the formula of 0.1% retinoic acid, 5% hydroquinone and 0.1% dexamethasone hydrophilic ointment, which was applied topically twice/d to treat hyperpigmentation with good effect, and later there was a modified kligman formula (0.5% retinoic acid, 4.0% hydroquinone and 0.05% hydroquinone). This formula reduces the concentration of the first two drugs and increases the strength of glucocorticoids to reduce local adverse reactions and increase the efficacy. (6) Chinese medicine: At present, Chinese medicine treatment for melasma advocates both internal and external treatment and is chosen according to the evidence. There is a report that Ermiao pill combined with mucopolysaccharide ointment of polysulfonic acid and vitamin A ointment has achieved better efficacy in the treatment of melasma.