Science of Laser Hair Removal

Growth Cycle

Lasers can only target hair when it is in the active phase of the growth cycle.  This phase is known as anagen, and it is the first of three phases.  Anywhere from 20% to 85% of hair can be in anagen at any given time. The next phase, known as catagen, is the beginning of regression.  During the final stage, known as telogen, the follicle is dormant as it prepares for the development of new hair.  Multiple laser treatments are necessary for effective hair removal, in order to target hair as it is in its active phase.

The chart below shows hair growth cycles for different areas of the body.  It charts what percentage of the hair in each area may be in the active anagen phase at any given time, compared to the percentage that may be in telogen, or the dormant phase.

Laser hair removal treatments require multiple sessions, based on intervals according to the growth cycle of the hair. The following chart shows the average duration, in months, of each phase of the growth cycle.  It may be used to estimate the necessary intervals between laser sessions.  It can be seen, therefore, how different areas of the body may need different intervals of treatment.

There are other factors which add to the need for multiple treatments and the desire for maintenance treatments, such as hormonal shifts in human physiology. The effects of laser hair removal are also dependent upon the characteristics of the hair such as coarseness, color, and depth of the follicle.  For these reasons, Dr. Goldboss evaluates all patients and individualizes all treatments.