There are more and more people with hair loss, both men and women, and seborrheic alopecia is the main cause of all kinds of hair loss. What are the factors that cause hair loss? Normal people on average lose about 50-80 hairs per day, which is a normal metabolism, and the number of hairs shed per day is roughly the same as the number of new hairs, so it does not become thinner. If the number of hair loss exceeds this number, and the hair is significantly thinner than before that is pathological hair loss, if the usual hair loss is not much, but the hair growth is very slow, hair thinning, this also belongs to pathological hair loss. Hair growth is divided into 3 phases, anagen phase, regression phase and resting phase, generally anagen phase 2-5 years, regression phase a few days, resting phase about 3 months. Hair loss causes the following points 1, endocrine disorders: hair loss is related to the increase of androgens in the human body. Dihydrotestosterone is one of the main androgens in the human body, mainly in the blood, because the nutrition of the hair to provide through the blood, so the increase of dihydrotestosterone in the blood will continue to affect the hair follicles, so that the hair follicles gradually atrophy, apoptosis, our hair will become more and more thin and soft, the formation of seborrheic alopecia. Another scholar found that there are many patients suffering from thyroid disease combined with hair loss, so hair loss is also related to thyroxine. 2, mental, nervous disorders: some young people work, life stress or long-term mental tension, depression and hair loss. 3, genetic: hair loss patients with a family history of 20%. In heredity, it is dominant for men and recessive for women, which is one of the reasons why there are more men than women with hair loss. 4, immune dysfunction: clinically, it is found that people with immune system disorders such as lupus erythematosus and ulcerative colitis are often accompanied by hair loss. 5, focal infection: infection caused by microorganisms can lead to necrosis of hair follicles and produce hair loss. 6, improper diet and fat metabolism disorders: some young people excessively like to eat meat, alcohol, when the body produces a lot of cholesterol can make too much sebum, which affects the blood supply of hair follicles. Impede the normal growth of hair and cause hair loss. 7, blood deficiency and kidney deficiency: Chinese medicine believes that hair loss is the result of blood deficiency and kidney deficiency. 8, hair damage: foreign experts have pointed out after investigation, long-term use of hair dye, hair loss can occur in 2 to 20 years. In addition, the frequent use of hair dryers, fire pliers, electric heaters perm, can also cause hair loss. In order to prevent hair loss to develop some of the following good habits: 1, do not use nylon combs and head brushes, because nylon combs and head brushes prone to static electricity, will bring adverse stimulation to the hair and scalp. The ideal is to use boxwood comb and hog bristle head brush, can remove dandruff, increase the luster of the hair, but also massage the scalp, promote blood circulation. 2, moderate shampooing, should not be too frequent, shampooing at the same time need to rub while massaging, not only to keep the scalp clean, but also to increase the blood supply of the scalp. Of course, if the hair greasy should be diligent washing. 3, do not use a strong degreasing or alkaline shampoo, this type of shampoo degreasing and dehydration are very strong, easy to make the hair dry scalp necrosis. Should use natural shampoo that is not irritating to the scalp and hair, or according to their own hair quality. 4, pay attention to nutrition, eat more vegetables and fruits, eat less stimulating food, take more vitamins Of course, if there has been hair loss, it is best to see a dermatologist in time. The first thing is to distinguish the type of hair loss, so that you can treat the symptoms.