This can occur on many people and is related to diet, lifestyle habits, and autoimmunity. Only one very long white hair grows out, no other uncomfortable symptoms is normal, do not worry too much. This is due to a certain hair follicle melanin deficiency, there is no impact on health, usually can eat appropriate melanin content of food, such as black sesame, black beans, etc., pay attention to observation. If the skin is white in addition to white hairs, and the number of white hairs is gradually increasing, consider vitiligo or leukoplakia, due to the lack of melanin in the affected area, poor blood circulation, can not supply the nutrients required by the hair, it is recommended to do skin CT or Wood’s lamp examination at the hospital to confirm the diagnosis and treat the symptoms. The original disease will be cured after the black hair grows, usually do local massage properly, it will help the disease recovery.