The common causes of hair suddenly white a lot include physiological factors and pathological factors (including pernicious anemia, vitiligo, etc.). 1. physiological factors: usually with age, the human body tissues and organs gradually aging, tyrosinase activity is reduced, melanin synthesis is reduced, prone to the phenomenon of hair whitening, in the intense mental stimulation, depression, long-term stay up all night, etc., easy to accelerate the speed of hair whitening, resulting in a lot of hair suddenly white. 2. Pathological factors (1) pernicious anemia: this disease is mainly due to gastric mucosal atrophy, the lack of internal factors, resulting in vitamin B12 absorption disorders, the pathogenesis is still unclear, may be related to race, heredity and so on. Due to pernicious anemia in the body, pigment cell synthesis of melanin is insufficient, prone to sudden white hair phenomenon, often accompanied by fatigue, dizziness, shortness of breath after activity, palpitations and other anemia manifestations. (2) Vitiligo:The etiology of this disease is unknown, may be related to autoimmunity, oxidative stress, melanocyte self-destruction, heredity, neurochemical factors, etc., manifested as a large number of white patches of skin and mucous membranes, when the lesions invade the scalp, it will lead to the symptoms of the head of the skin white patches, hair suddenly turned white. It is recommended that patients combine their own situation, if you suspect that the disease is caused by the need to go to the regular hospital dermatology department in a timely manner, after a clear diagnosis, timely treatment, to avoid delaying the condition.