Alopecia areata can be divided into the following categories according to the severity of hair loss and the etiology of hair loss (1) Pseudo-baldness: Most of the baldness has one or several hair loss areas, and the disease lasts for several months. It is a type of chronic progressive scarring baldness with no obvious causative agent, as opposed to pemphigus vulgaris. The bald spots are round, oval or irregular in shape, and scarring is formed due to local skin atrophy. (2) Total baldness: All the hair is lost. (3) General baldness: In addition to the loss of all hair, eyebrows, beard, armpit hair, body hair, etc. all begin to fall out. 2.There are four types of hair loss according to their causes: hereditary, prehypertensive, autoimmune, and the most common type, common baldness. (1) Hereditary baldness: Familial inheritance is also a major factor in the development of baldness, which can be treated by skin expansion repair or hair transplantation. (2) Pre-hypertensive baldness: It is caused by people with high blood pressure, and the first step in treatment is to control high blood pressure. Autoimmune baldness and the common type generally require long-term treatment, which can be combined with the use of traditional Chinese medicine.