Why do girls lose their hair, adults are metabolizing hair follicles every day, a certain amount of hair will fall out every day, usually no more than a hundred, if more than this amount you need to find the cause. Common causes: first, chemical damage, improper selection of shampoo products, chemical perm and the wedge method can damage hair follicles and cause hair loss; second, malnutrition, excessive dieting, resulting in protein, caloric deficiency, will affect the growth of hair follicles and cause hair loss; third, mental tension, excessive mental tension will lead to the scalp small arteries contraction, hair follicles ischemia, hypoxia and hair loss; fourth, seborrheic dermatitis. The fifth, fungal infection, when the scalp is infected by fungus, not only the itching and increased dandruff caused by fungal infection, but also affects the hair stem causing hair breakage and damage to the hair follicle and cause hair loss.