Hair has 3 phases of growth: growing, sleeping and shedding. At any given point in time, some hairs in any given area are growing, while others are shedding or sleeping. The laser sends out a beam of light that is attracted to the dark colour in your hair root when it is in the growing phase at the time of your treatment. Once the growing hair root attracts the laser energy, the growth of the hair is stopped; the hair follicle is disabled and killed.
The killed hair follicle will push its way to the surface and will fall out approximately 2-4 weeks after the treatment, and does not grow back. The hairs that are sleeping or shedding at the time of your treatment, will eventually enter the growing phase at different times. Since the laser does not kill hair follicles that are in the sleeping or shedding phases, you will require more than one treatment to disable and kill all of the hairs in a given area.
It is important for the laser machine to see the root of your hair so that it can work properly, so it is not advisable to wax or tweeze the hairs in between your treatments, since this will remove the root. You may shave in between treatments, however. The laser beam is attracted to dark colours, and so laser hair removal will not work if your hairs are white or red. At your consultation with Dr. Zakhary, she will advise you of other options that may be available for you in this case.