Melasma, also known as liver spots, is a yellowish-brown pigmentation on the face. It is mostly distributed on the cheeks in a symmetrical butterfly shape. It is mostly seen in women, and the high level of estrogen in blood is the main cause. Its onset is related to pregnancy, long-term oral contraceptive use and menstrual disorders. The etiology is unknown. It is mostly seen in women, and high blood estrogen levels are the main cause. Its onset is related to pregnancy, long-term oral contraceptive use, and menstrual disorders. It is also seen in some patients with female reproductive system disorders, tuberculosis, cancer, chronic ethanol poisoning, liver disease, etc. Sunlight can contribute to the onset of the disease. Male patients account for about 10% of cases, and some studies suggest that male onset is genetically related. The lesions are yellowish brown or dark brown patches, often symmetrically distributed on the zygomatic cheeks, but may also involve the periorbital area, forehead, upper lip and nose, with generally distinct margins. There are no subjective symptoms and general discomfort. The shades of pigmentation are related to season, sunlight and endocrine factors. Mental stress, staying up late and exertion may aggravate the lesions. Most of the melasma is caused by the blockage of microcirculation between tissue cells and the increase of melanin to form pigmentation. The epidermis of the face is the thinnest layer and the capillaries are the most abundant, so the pigmentation area is mainly in the basal layer of epidermis. Most of the chloasma is caused by the following aspects: 1, imbalance of yin and yang in human body: one because of liver qi stagnation, resulting in blood stasis on the face; two because of spleen and stomach weakness, qi and blood cannot moisten the face, damp heat rises to the face to form spots; three because of kidney yang deficiency, yang diffusion, blood stasis on the face to form chloasma. 2. After pregnancy, the placenta secretes more androgen and progesterone, so symmetrical distribution of chloasma is common on the cheeks of women during pregnancy, but after the secretion of androgen and progesterone in the body returns to normal, most people’s spots will naturally reduce or disappear. 3.Drug factor: 9%-20% of women who take oral contraceptives for a long time are prone to chloasma, and some people even have facial spots after taking oral contraceptives for one month: in addition, taking high blood pressure and diabetes medicine and eating more food with stronger light sensitivity, such as celery, parsley and carrot, are also prone to chloasma. 4, other factors: some chronic diseases such as chronic hepatitis, tuberculosis, etc. will lead to the enhancement of tyrosinase activity and increase of melanin production, while the body’s own ability to exclude melanin is weakened, once melanin can not be discharged from the body in time, chloasma will be produced on the face over time; in addition, improper use of cosmetics will also aggravate and accelerate the formation of chloasma, many causes of pigmentation.