Laser hair removal is simple and effective. The goal is to eliminate the hair root by targeting melanin. This concept is known as “selective photothermolysis.” The laser emits infrared rays that focus on the melanin concentrated within the hair and are converted to heat that destroys the entire follicle. Laser destruction is selective since it only targets very dark colors, like dark hair, leaving fair skin undamaged. The wavelength of the light beam is configured according to skin phototype and hair color.
Laser hair removal is particularly effective when hair is in the growth phase (anagen), since this is when melanin is present in the highest concentrations. Since it isn’t possible to determine the growth phase of each individual hair, it’s important to undergo several sessions to ensure all hairs are eliminated. Follicles in the resting phase (catagen) are completely transparent, containing no melanin at all, which is why lasers are not effective at that stage. In sum, the thicker and darker the hair, the more quickly it will be eliminated. Similarly, to remove downy hair, many more sessions must be completed because downy hair also tends to thicken rather than thin out at the start of treatment.
Over time, laser hair removal makes individual hairs thinner and slows down growth little by little until it stops completely, after 5 to 6 sessions.
Laser hair removal is not effective against white, blond, or red hair, which contains little to no melanin. As for skin color, hair removal lasers such as the Nd Yag laser now exist and are specifically designed for black and brown skin (which have higher levels of melanin) to avoid burns. For fair skin, the laser technician generally uses the Alexandrite laser.
The success of laser hair removal is evidenced by:
- Hair growing in thinner and thinner
- Hair taking longer and longer to grow back
- Fewer and fewer hairs growing back
- Hair getting lighter and lighter in color