Permanent hair removal mainly refers to laser hair removal, which mainly uses selective photothermal action to make the abundant melanin in the hair follicle and hair shaft absorb laser energy into heat, which rapidly increases the local temperature, destroys the hair follicle tissue, removes the hair so that it will not grow again, and does not damage other surrounding tissues. In theory, laser hair removal is permanent. However, in practice, it is difficult to achieve absolute no hair growth and there may be a very small amount of residual hair, usually in a very fine and soft, light-colored state, with better final results. It is important to note that hair growth is cyclical. The laser is only effective on the hair in the anagen phase, but not on the hair in the regressive and resting phases, and the hair growth cycle is different in different parts of the body, so the treatment interval is different. In addition, different parts of the hair color, density, the number of treatment required and the final effect is different, such as armpit hair, trunk limbs hair do about 3-6 times, you can achieve better results, while the female lip hair treatment effect is worse, the number of treatment required more.