Many patients wonder why they experience hair regrowth after their laser treatment.
Laser hair removal permanently reduces the number of hairs. Only hairs that are in the active growth phase (ANAGEN) respond most effectively to laser treatment. Also because dark hairs contain more melanin, these would also respond better to lasers compared to light hairs. Melanin is necessary to absorb the laser light so that it can affect the follicle. .
Since up to half of the hair at any given time can be in the resting phase (TELOGEN), almost half of the hair would not respond.
That is why serial and multiple treatments are necessary. Also, hair growth cycles are different for different patients. This is usually governed by genetics.