Most areas require 3-6 treatments. However, the number of CoolGlide treatments required for optimal long-term benefits depends on multiple factors - hair thickness, the area treated and your hair's growth cycle. Interestingly, not all hairs are actively growing at the same time and actually go through three distinct phases: growth, regression, and resting. CoolGlide treatments work by disabling the hair that is principally in the active growth phase at the time of treatment. Since other hairs will enter this active growth phase at different times, additional treatments may be necessary to disable all of the hair follicles in a given area.