The causes of hair loss include physiological factors, androgenetic alopecia, spot baldness, scarring alopecia, etc. 1. Physiological factors: Generally speaking, it is a normal physiological phenomenon to lose 70~100 hairs per day. When hair growth enters into the resting phase, the old hairs will fall off and be replaced by newborn hairs. If a large number of hairs enter the resting phase at the same time, there may be a temporary large number of hair loss performance, and recent malnutrition, mental stress, seasonal changes, etc. Related. 2. Androgenetic alopecia: It is mainly related to genetic factors, increased individual androgen levels, increased individual sensitivity to androgens, scalp microcirculation disorders or fungal infections, excessive mental stress, irregular work and rest, etc., all of which can lead to androgenetic alopecia. 3. Patchy baldness: closely related to immune system disorders, such as excessive stress, or suffering from atopic dermatitis, autoimmune thyroid disease, dry syndrome and other diseases; also has a certain relationship with the family genetics, patchy alopecia can occur. 4. Scarring alopecia: related to scalp trauma, repeated scalp infections, scalp tumors, immune dysfunction, progressive necrosis of lipoid, tuberculosis and other reasons, can also lead to the phenomenon of total hair loss. If the hair loss is more and the performance is abnormal, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease, and follow the doctor’s instructions to standardize the treatment.