Very long white sweaty hairs on the arms may be related to heredity, vitiligo and other factors. 1. Genetic factors. Hair color has a certain genetic inheritance, for the family has white hair gene people appear white sweat hair will have a higher chance. No special treatment is needed. 2. Vitiligo. Vitiligo is a kind of acquired pigmentation deficiency disease, in the clinic will be manifested in the size of the white spots, in which the white parts of the hair can be presented as white. In the treatment of vitiligo after the effect of the hair will also become black. Because of the complexity of the cause of the disease, the specific circumstances need to ask the doctor for an interview, by the doctor to guide the use of medication.