Your hair is not in your skin¦technically. The dead hair shaft which we see comes through the skin but the hair follicle or bulb, the live part of hair, sits below the deepest part of the skin. This bulb is what laser hair treatments target. Specific wavelengths of laser light are geared towards the dark color of the hair bulb to heat it up and destroy it. The darker the hair color, the better attraction for the laser light. Lighter hair colors attract less of the laser light, decreasing its effectiveness. In addition, the laser light must pass through the skin to get to the hair bulb, which is why all laser hair treatments pose some risk for skin burns. Lasers are designed to try and get the most energy deep down to the hair bulb which not injuring the skin along the way. This is why darker pigments in the skin, either from natural skin pigments or having a tan, pose both challenges and increased risk of skin burns. For these reasons, the best laser hair treatment results occur in those with dark hair and light colored skin.
Dr. Barry Eppley