Everyone loses hair, but some people lose more and some people lose less. Hair has its own life span, and when it reaches a certain length, it will die of old age and fall out naturally. If you lose more than 100 hairs a day, it may be abnormal hair loss. Unusual hair loss is due to the fact that hair growth is affected, making the whole hair look thin. In recent years, more and more people are losing their hair, and some even lose it piece by piece, eventually becoming bald. Common pathological hair loss include seborrheic alopecia, androgenic alopecia, baldness and scarring alopecia. Alopecia areata is commonly known as “ghost shaving”. Patients with alopecia areata often have circular hair loss areas on their heads, the boundaries of which are obvious, with varying numbers and sizes, and the hair at the edges of the areas is easy to pull. If the symptoms of baldness continue to develop, all the hair will be lost, which is called total baldness. If hair loss is noticeable on the top of the head, it is called baldness. There are many reasons for abnormal hair loss, mainly related to overuse of the brain, or frequent preoccupation, boredom, or encountering something, mental tension and stress, followed by genetic, immune and neuroendocrine changes, nutritional excess or malnutrition, changes in living habits, shampoo for dyeing and perming, air pollutants, harmful radiation, lack of trace elements, acute infectious diseases, long-term use of certain The factors are also related. Baldness is generally seen in men because of the excessive secretion of androgens in their bodies. The sebaceous glands are mainly controlled by androgens, and if androgens are secreted excessively, the top of the head will secrete too much oil. When the pores on the top of the head are blocked by oil, the supply of nutrients to the hair will be impaired, which will eventually lead to gradual hair loss and eventually baldness.