As hair goes through its growth cycle, it moves through three distinct phases: anagen, catagen, and telogen. Understanding these phases can help you better understand how laser hair removal works and why multiple treatments may be necessary to achieve desired results.
Anagen phase is the active growth phase where the hair follicle produces new hair cells. During this phase, laser hair removal is most effective as the energy from the laser targets the melanin in the hair follicle, damaging it and preventing regrowth. Catagen phase is a transitional phase where growth stops and the hair follicle shrinks. Laser hair removal during this stage may not be as effective since there is less melanin for the laser to target. Finally, in the telogen phase, the old hairs fall out to make room for new hairs to grow during anagen. At any given time, different hairs on our body are in various stages of these phases.