Laser hair removal is to destroy the hair follicle structure by laser, so as to achieve the effect of hair removal. Therefore, laser hair removal is closely related to the growth cycle of hair. The current laser hair removal can not completely destroy the hair follicle at one time, but through multiple laser hair follicle destruction.
Generally, the growth of hair is divided into growth period, degenerative period and quiescent period. The hair in the growth stage contains the most melanin and is extremely sensitive to laser, while the hair in the degenerative and quiescent stage is not sensitive to laser energy. Therefore, laser hair removal will choose to treat in the growth period of hair. Each course of laser hair removal is generally required to be separated by about 4-8 weeks. After new hair grows, laser hair removal treatment is carried out again. Because different individuals, different parts and different hairs have different requirements for laser hair removal treatment, the number of courses is different. However, after 3-5 courses of treatment, the best effect of depilation can be achieved. Permanent laser hair removal does not mean that hair will never grow. The understanding of the U.S. Food and Drug Administration for permanent hair removal is that hair will no longer grow in a hair growth cycle after laser or strong light treatment. Even if there is hair regeneration, the color is very light, thin and short.