Why are multiple treatment sessions required for laser hair removal?

Multiple treatment sessions are necessary for laser hair removal primarily because hair grows in cycles. Human hair goes through three distinct phases: anagen (the active growth phase), catagen (the transitional phase), and telogen (the resting phase). The laser is most effective when hair is in the anagen phase because this is when the hair has the most pigment, allowing the laser energy to be absorbed effectively.

Since not all hair follicles are actively growing at the same time, some hair will be in the anagen phase while others will be in different stages of growth during any single treatment. Therefore, multiple sessions are required to target the hair in the anagen phase, progressively reducing the overall hair density in the treated area. This aspect of hair growth cycles is crucial for achieving optimal long-term results from laser hair removal.