The CoolGlide laser uses heat to disable the hair follicle, preventing regrowth. It directly targets the bulb and bulge of the hair follicle. These are the areas responsible for regrowth.
Multiple treatments are required to achieve sufficient reduction in hair growth because each hair goes through three growth phases (anagen, catagen, telogen). The hair follicle can only be disabled during the anagen phase. Each hair passes through these growth phases at different times, thus multiple treatments are required.