Common causes of thinning hair include physiological factors, endocrine disorders, drug factors, scalp infectious diseases and so on. 1. Physiological factors: In general, if the long-term diet irregularities, resulting in a lack of certain nutrients, vitamins, trace elements in the body, will affect the growth of hair, can appear thinning hair phenomenon. In addition, if the family, the parents of the hair is relatively thin not long, then their offspring are prone to inherit this hair, the phenomenon of thinning hair not long. 2. Endocrine disorders: if long-term fatigue, too much pressure, mental stress, anxiety, thyroid function abnormalities, etc., can lead to endocrine abnormalities in the body, affecting the normal metabolism, can appear thinning hair phenomenon. 3. Drug factors: If long-term use of chemotherapy drugs, contraceptives, anticoagulants, etc., there will be hair thinning side effects. 4. Scalp infectious diseases: If there are infectious diseases in the scalp, such as ringworm, folliculitis, etc., the hair follicles are damaged, which will affect the normal growth of hair and may or may not appear the phenomenon of thinning hair. It is recommended that patients exclude physiological factors, need to go to the regular hospital dermatology consultation, follow the doctor’s instructions combined with the relevant examination, a clear diagnosis, active treatment.