The causes of forehead whitening include physiological factors, vitiligo and so on. 1. physiological factors: if the patient age, at this time due to the weakening of the function of the enzyme, so there will be the phenomenon of forehead white, this is a physiological phenomenon, do not need to worry too much. 2. Vitiligo: with heredity, autoimmune, mental factors, etc., when a variety of factors triggered by the reduction of melanin production, then there will be the phenomenon of local hair white.