The causes of facial hair include physiological and pathological, and the causes of pathological facial hair include adrenal diseases such as cortisolism and ovarian diseases such as polycystic ovary syndrome. 1. Physiological reasons: Sweat hair will appear on the face of normal people, which is a normal phenomenon. This is a normal phenomenon. The amount of sweat hair on the face varies from person to person due to the different physique of each person and the different sensitivity of the body to hormones. 2. Pathological reasons: adrenal diseases such as hypercortisolism or increased levels of androgens, resulting in exuberant hair. Ovarian diseases such as polycystic ovary syndrome is a common cause of increased sweating, not only on the face increased sweating, arms, legs and other parts of the body will also appear hairy phenomenon. Other diseases: malignant tumors such as lung cancer and anorexia nervosa can cause excessive hair growth. When hair grows on the face, accompanied by obvious physical discomfort, it is recommended to go to the hospital immediately.