The condition of sweaty hair on the arms of girls is often called hirsutism. The reasons for this are as follows: First, there is a family heredity, which is more common in the clinic. Secondly, it is related to the body’s hormone level, especially the androgen level is increased, or endocrine abnormalities. Third, it may also be related to some endocrine-related diseases, or some other internal diseases taking certain drugs, such as cyclosporine, these drugs may also lead to the situation of increased sweat hair. There are many reasons for the increase in sweat hair on the arms of girls, and it is advisable to clarify the possible causes as much as possible under the guidance of a regular professional doctor, and to take appropriate methods for treatment according to the situation.