Vitamin B12 does not treat hair loss. Vitamin B12, also known as cobalamin, is the only vitamin in the B vitamin group that contains metal elements and has a very important role in the development of brain tissue and the nervous system. Therefore, it is commonly used in the treatment of neurological disorders such as cerebral leukodystrophy, Alzheimer’s disease and Parkinson’s disease, and has no role in treating hair loss. Hair loss is often related to a variety of factors such as sleep, diet, mental state, genetics, metabolism and disease, etc. A common type of hair loss is androgenetic alopecia. The hair follicles in the hair loss area are shortened in the anagen phase and prolonged in the resting phase, accompanied by atrophy of the hair follicles. Therefore, the hair growth process may show the characteristics of thin and short, easy to fall off, or even enter the regression phase before the hair reaches the skin surface, resulting in no hair growth in the hair loss area. Usually androgenetic alopecia can be regulated by oral finasteride to regulate the hormone level and enhance the quality of hair, but this drug is only for androgenetic alopecia. Topical medication, commonly Minoxidil, can stimulate the differentiation and proliferation of hair follicle epithelial cells, enhance local blood circulation, shorten the resting period of hair growth, and prolong the anagen phase. Hair transplantation is the most effective, long-lasting and ideal way to treat hair loss, and there are also acupuncture, laser and other treatment methods, patients can choose the appropriate treatment after the doctor’s diagnosis. In addition to the medication prescribed by the doctor, patients should also avoid staying up late, drinking alcohol, smoking, as well as greasy and spicy diet to reduce the stimulation of hair follicles. Choose a soothing and mild shampoo with little irritation, and massage with fingertips while washing hair, do not scratch with fingertips to reduce damage, and blow dry hair before going to bed or leaving home.