The common causes of back hair growth include androgen secretion and genetic factors. 1. Excessive secretion of androgens: The secretion of sebaceous glands in hair follicles is regulated by sex hormones. Androgen is a kind of sex hormone, which promotes the growth of human muscles and the development of sex organs. If androgen secretion is exuberant and the level of hormones in the body is imbalanced, it is easy to stimulate the growth of hair, which will also lead to the abnormal growth of hair and make the phenomenon of back hair growth. 2. Hereditary factors: usually some people, parents who have heavy hair, back hair, then their offspring will also appear back hair phenomenon, if there is no other discomfort, then there is no need for treatment, usually does not affect the health of the body. It is recommended that the patient according to their own situation, if you suspect that the androgen secretion is due to the exuberant, need to go to the regular hospital in time, follow the doctor’s instructions to clarify the diagnosis, reasonable treatment, to avoid delaying the condition.