The common causes of armpit hair in women include heredity, polycystic ovary syndrome, medication and so on. 1. Genetic factors: Under normal circumstances, if the parents or grandparents in the family have more hair, axillary hair growth is exuberant, then it belongs to the genetic factors, the phenomenon of armpit hair in the offspring of the children, and will not affect the health of the body. 2. Polycystic ovary syndrome: women with polycystic ovary syndrome, will lead to the body androgen exuberant, hormone level changes, will stimulate the growth of hair, the phenomenon of armpit hair. 3. Drug factors:If long-term use of hormonal drugs, such as prednisone, hydrocortisone, etc., prone to armpit hairy side effects. It is recommended that patients according to their own situation, if suspected of disease, timely to the regular hospital dermatology consultation, follow the doctor’s instructions reasonable treatment.