1. Formation of black spots
(1) Ultraviolet rays are the number one killer of spots. Generally, melanin deposition caused by sun exposure will be discharged with human metabolism, but some people may have slower metabolism or be older, leaving melanin and forming dark spots.
(2) Metal poisoning caused by the use of expired or inferior cosmetics, such as lead, mercury and arsenic poisoning.
(3) When the skin is injured, foreign bodies such as dust and ink are embedded in the wound; Use iodine and purple potion; Or overeating foods containing pigments, such as soy sauce and black fungus, will cause pigment deposition and form black spots.
(4) Living habits. Bad living habits such as stress, partial eclipse and lack of sleep will also increase melanin. Therefore, the skin metabolic rate of people with unstable sleep time is poor, which will affect the production of melanin particles.
2. The formation of freckles
(1) Genetic factors are the main causes of freckles, not necessarily from parents, but possibly from several generations. Generally speaking, freckles appear on the face with whiter skin.
(2) Sunlight, ultraviolet rays in sunlight frequently stimulate the activities of subcutaneous pigment cells, producing a large number of melanin; On the other hand, it damages the normal metabolic function of skin cells, so that melanin can not be discharged smoothly and remains on the skin, even deposited in the dermis. Therefore, excessive sun exposure will aggravate and deepen freckles, but freckles will gradually fade in winter.
3. The formation of chloasma
It is because the microcirculation between tissues and cells is blocked by siltation, cells dissolve and die, and melanin increases to form pigmentation. The epidermis of the face is the thinnest, the capillaries are the richest, and pigmentation is the easiest to form. The pigmentation site is mainly in the basal layer of epidermis, and the melanin particles increase obviously. In more serious cases, there are more melanin in melanophagous cells in dermis. Compared with normal, the number of pigment cells, the formation of melanin and the activity of melanin particles have increased to varying degrees.
(1) imbalance of yin and yang in human body, one is due to stagnation of liver qi, which leads to facial blood stasis; Second, due to the weakness of the spleen and stomach, qi and blood can not moisten the face, and damp heat rises to the face to form spots; Third, due to the deficiency of kidney yang, yang disperses blood stasis, forming chloasma on the face.
(2) After pregnancy, the placenta secretes more androgens and progesterone, so chloasma symmetrically distributed on the cheeks of pregnant women is common. However, after the secretion of androgen and progesterone in postpartum body returns to normal, most people's spots will naturally fade or disappear.
(3) Drug factors: 9% ~ 20% of women who take oral contraceptives for a long time are prone to chloasma. Some people even have spots on their faces after taking oral contraceptives for a month. In addition, taking drugs for hypertension and diabetes and eating more sensitive foods, such as celery, parsley and carrots, are also prone to chloasma.
(4) Some chronic diseases, such as chronic hepatitis and pulmonary tuberculosis, will increase tyrosinase activity and melanin production, while the body's ability to eliminate melanin will be weakened. Once melanin cannot be excreted in time, it will also produce chloasma on the face over time; In addition, improper use of cosmetics will aggravate and accelerate the formation of chloasma, resulting in many spots.
4. The formation of pregnancy spots
In fact, the principle of pregnancy spots and pregnancy marks is the same, both because of the special physiological conditions during pregnancy. Hormone changes during pregnancy will promote the temporary increase of melanin in the body. Melanin is a naturally occurring substance in the human body, and the colors of hair, skin and eyes all come from it. After a few months of delivery, the pigmentation during pregnancy is likely to gradually subside and the skin should be able to return to normal color. However, some women's pregnancy spots will not completely disappear, and some safety measures can be taken to minimize the deepening of skin color.