We use an alexandrite laser for hair reduction.

We have always thought that the laser cosmetic procedure for hair reduction was the best option as it more precisely targets the pigment in the hair follicle.

The Alex laser targets pigment in a large structure so the laser mostly targets pigment in the follicle which is like a bulb/root under the surface of the skin from where the hair shaft grows.

The laser light passes through the skin till it finds the pigment in the large structure /follicle and converts to heat.

So if enough laser light finds enough pigment in the follicle to convert to enough heat to destroy the follicle completely, then that follicle is gone and its hair is removed permanently.

If a fragment remains, it may regenerate into a new follicle which is usually smaller and would produce a finer lighter hair.

So most of the hairs are removed and some are miniaturised.

Also there is only pigment in the follicle during anagen or growth phase so only those hairs in the growth phase are treated in this cosmetic procedure.

And those hairs in dormant or resting phase will need to come into growth phase to be treated.

Therefore multiple laser treatments are needed.

Also as pigment is the target, so lighter hairs (grey, white, blond, and very fine hairs) may not have enough pigment in their follicle to convert to enough heat to be treated.

For the same reason if the skin is tanned or otherwise pigmented (even with fake tan or makeup), then the laser light may heat up the skin causing side effects like crusting scabbing or pigment change.. 

Also it is important not to wax for a few days as if wax or pluck, then the hair is pulled out of follicle and the laser loses its target. So better to cut or shave hair as this removes hair above surface of the skin leaving target hair and pigment for the laser to hit in the follicle below.

If you have dark skin you may need revlite laser as this laser targets water in a large structure not pigment and is a safer laser in darker skin types, but only works on larger thicker hairs.