Severe hair loss may be caused by physiological factors such as high stress and late nights, or it may be caused by diseases such as androgenetic alopecia and baldness. 1. Physiological factors: if the patient is under long-term stress, or often stay up late, irregular life and routine, the symptoms of severe hair loss may occur. 2. Androgenetic alopecia: patients mainly show that their hair is thinning, thinning and falling out. The cause of the disease is related to heredity, androgen changes and other factors. 3. Patchy baldness: patients will have round or oval hair loss area, the skin at the hair loss place is smooth, and the hair at the edge of the hair loss area is loose and easy to pull out. The cause of the disease is related to immune abnormality, in addition, mental stimulation, infection and allergy will also increase the chance of the disease. There are many reasons for severe hair loss. After ruling out physiological factors, patients are advised to go to the hospital to clarify the cause of the disease.