Melasma occurs on the face, more or less symmetrically, with well-defined borders. The lesions are light brown, coffee-colored or light black patches of variable size and irregular shape with clear borders. Pigmented spots occur only on the face, usually symmetrically distributed near the eyes, forehead, cheeks, nose, lips or near the mouth, without inflammation or other changes, and without causing conscious symptoms. The skin pigmentation of the areola and external genital area may deepen. The cause of this disease is variable, and some patients have no identifiable cause, which can be called idiopathic melasma. Some women who suffer from dysmenorrhea, chronic diseases of uterus, ovarian inflammation and other diseases of reproductive organs can have chloasma on their face at the same time, which can be called uterine chloasma. Some pregnant women have chloasma, which often appears in the third to fifth month of pregnancy and can be called gestational chloasma, which will disappear gradually after delivery. In recent years, chloasma appears after some people take birth control pills for 1 to 20 months. Some people think that the estrogen melanocytes contained in birth control pills and the progesterone contained in them make the pigmentation spots expand. In addition to sexual endocrine dysfunction, other endocrine disorders such as hypothyroidism or pituitary gland function, adrenal cortex hypertrophy, etc. can also be related to melasma. Chronic diseases can be the cause. Some melasma patients suffer from chronic gastrointestinal disease, chronic liver disease, tuberculosis, malignant lymphoma or some kind of malignant tumor in the body at the same time. Malnutrition caused by protein deficiency and vitamin deficiency may be one of the causes. The authors found that most patients were pale and malnourished, and when nutrition improved, the pigmentation often disappeared. Although there is no family history of this disease, it is thought that congenital constitution may be related to this disease. Sunlight may not be the cause of the disease, but strong sunlight can deepen the color of damage, and chloasma is more obvious in summer. It is also reported that the disease is related to cosmetics, and the authors believe that the latter should be the pigmentation type of cosmetic dermatitis, but sometimes it is difficult to distinguish between the two. Treatment of melasma should look for the cause and treat it appropriately. For example, hypothyroid patients should be treated with thyroid tablets and malnourished people should be given better nutrition. Large amounts of vitamin C are often applied. Avoiding sunlight can lighten the color of the damage, and sometimes shading agents can be applied to reduce the effect of sunlight. Hydroquinone can prevent the oxidation of tyrosine into dihydroxyphenylalanine and has a fading effect. Usually, 2% to 5% hydroquinone cream is applied 2 to 3 times a day, which can gradually make the color fade after 1 to 2 months. Hydroquinone can also be combined with other drugs to form a fading agent, for example, prescription: 0.1g of retinoic acid, 5g of hydroquinone, 0.1g of flumethasone, hydrophilic ointment or ethanol added to 100g. or 2g of salicylic acid, 5g of hydroquinone, 0.025% of flumethasone ointment added to 100g.