Overall, 80% of study participants report a 95% level of permanent hair removal. Numerous studies have been conducted on the degree of permanent hair reduction. Plus, if a follicle wasn’t fully disabled, it may return to growing hair. Second, damaged follicles can rebuild with hormonal changes. The darkness of the hair can also play a part (laser hair removal isn’t as effective on lighter hair due to the lower amount of melanin). So, laser hair removal needs to be repeated in a series of treatments to catch the hairs in the anagen cycle. Every hair on the human body is independent and works alone. And the laser energy can’t get into the follicle to damage it. That’s why lasers don’t affect hair in these phases they’re already on their way out.
The catagen and telogen phases involve stopping nourishment to the hair, shedding it, and restarting a new hair shaft. But hairs can also be in the catagen (transitional phase between growth and rest) or the telogen phase (rest).
First, lasers only damage hair in the anagen (growth) cycle. FDA approval is for “permanent hair reduction.” What does that mean? It means that no laser can permanently remove all of the unwanted hair.