Usually, hair loss caused by physiological factors can grow back; hair loss caused by pathological factors may be difficult to grow back. Hair is divided into anagen, regression and resting phases, and more hair is lost during the regression and resting phases. If the hair loss is caused by normal metabolism, the hair follicle is not damaged, and the hair will grow again after the anagen phase. However, if it is pathological hair loss, such as acute and chronic infectious diseases, skin diseases, endocrine disorders, etc., the lesion will destroy the scalp hair follicles, and permanent hair loss will be formed, and it will be difficult to grow again. Under normal circumstances, the number of hair loss is around 70-100 per day. If the number of hair loss is large, it is mostly pathological hair loss, which requires timely consultation to the dermatology department to treat the suitable treatment plan according to the cause to avoid the increasing aggravation of hair loss. In addition, the usual mental tension or sudden mental stimulation can also cause serious hair loss, it is recommended to maintain a calm state of mind, ensure good sleep, eat more fresh fruits and vegetables, and pay attention to hair care.