The possible causes of hair fall in winter include resting hair loss, endocrine disorders, and folliculitis alopecia. 1. Resting hair loss: The hair growth cycle includes three periods: the growth period, the degeneration period and the resting period. Cold and dry weather in winter, the body’s metabolic rate slows down and other factors may cause changes in the regulation of the hair growth cycle, so that a certain proportion of the growth period of the hair quickly to the transition to the resting period, thus causing hair loss, showing that the winter hair loss is very strong. 2. Endocrine disorders: winter weather is cold, everything is depressed, if the patient at the same time there is too much mental stress, a long time to stay up all night and other situations, may lead to patients with endocrine disorders, thus causing the scalp sebum secretion exuberant. In severe cases, sebum clogs the pores, causing the destruction of the hair root and hair loss. 3. Folliculitis alopecia: some patients do not pay attention to good scalp cleaning in winter, scalp hygiene is poor. This may lead to bacterial infection, triggering scalp folliculitis. When the follicle inflammation involves the hair root is heavy, it may cause folliculitis alopecia, manifested as winter hair loss. To summarize, it is recommended that patients with severe hair loss in winter go to the hospital to clarify the cause of the disease and receive timely treatment to avoid further aggravation of the condition.