Sweat hair on the legs fell off a piece may be caused by malnutrition, repeated friction, local lesions and so on. 1. Malnutrition: refers to a state in which energy or protein, vitamin and other deficiencies caused by various reasons are unable to maintain normal metabolism, resulting in the depletion of one’s own tissues. Its main manifestation is the reduction of subcutaneous fat, edema, anemia, hypoglycemia, dry skin, hair loss and other symptoms. This can lead to sweat hair on the legs fell a piece. 2. Repeated friction: If the pants are worn too tightly or often rub the legs, it can also cause local hair loss, which can lead to a piece of sweat on the legs. 3. Localized lesions: bacterial infections, fungal infections, eczema, etc., can also lead to a patch of sweaty legs. There are many other causes of sweaty legs, so you should pay attention to them, consult a doctor in time to find out the cause of the disease, and follow the doctor’s instructions for further treatment or therapy.