The principle of selective photothermolysis relies on the presence of what substance in the follicle?

The principle of selective photothermolysis is fundamentally based on the absorption of specific wavelengths of light by targeted chromophores, which are substances that absorb light. In the context of hair removal, the key chromophore of interest is melanin, found within the hair follicle.

Melanin is the pigment that gives hair its color and is highly effective at absorbing the energy emitted by lasers or intense pulsed light (IPL). When these light sources are directed at the hair, the melanin absorbs the energy, which leads to the thermal destruction of the hair follicle. This process effectively disables the hair’s ability to grow without damaging the surrounding skin.

While other substances like collagen, oxygen, and keratin play important roles in skin structure and function, they do not serve as primary targets in the mechanism of selective photothermolysis for hair removal. Therefore, the presence of melanin in the follicle is crucial for the effectiveness of laser and light-based hair removal treatments. Its targeted absorption ability is what makes selective photothermolysis a successful method for achieving permanent hair reduction.