Hair, like all living things in the world, has a certain lifespan and is constantly growing, shedding and re-growing. From the time a hair follicle grows out of the scalp to the time it falls out, it takes 2 to 7 years, up to 25 years. The hair cycle is called the hair cycle. Adult hair is 85% to 90% in the anagen phase and 10% to 15% in the resting phase. The hair in the resting phase will be shed as soon as it is slightly stimulated, such as combing, washing, etc. It is normal to shed 75~100 hairs per day. People do not need to worry about hair loss when combing or washing hair. According to the normal metabolism of hair, hair is in absolute advantage during the growth period. If the normal hair cycle is disrupted by the stimulation of various harmful factors, so that the resting hair is shed prematurely or excessively, or the hair in the growth phase is shed without going through the resting phase, and more than 100 hairs are shed every day, this is considered to be the hair loss that needs treatment. The following types of hair loss do not require treatment, namely physiological hair loss, including natural hair loss, infantile hair loss, postpartum hair loss, and senile hair loss.