laser was performed experimentally for about 20 years before it became commercially available in the mid 1990s. Laser and light-based methods are sometimes called phototricholysis or photoepilation.

In addition to lasers, some light-based epilators use a xenon flash lamp which emits full-spectrum intense pulsed light (IPL) . Treatment with this device is sometimes popularly referred to as laser hair removal, though the device is not a laser per se.

Mechanism of action

The primary principle behind laser hair removal is selective photothermolysis. Lasers can cause localized damage by selectively heating dark target matter in the area that causes hair growth while not heating the rest of the skin. Light is absorbed by dark objects, so laser energy can be absorbed by dark material in the skin (but with much more speed and intensity). This dark target matter, or chromophore, can be naturally-occurring or artificially introduced.

Hair removal lasers selectively target one of three chromophores:

• Carbon, which is introduced into the hair follicle by rubbing a carbon-based lotion into the skin following waxing (this lotion is an "exogenous chromophore"). When irradiated by a Q-switched Nd:YAG laser, the carbon causes a shock wave capable of mechanically damaging nearby cells. This method has been abandoned since it does not cause permanent loss. (It has been replaced with the long-pulsed Nd:YAG laser which targets endogenous melanin in the follicle.)
  
• Hemoglobin, which occurs naturally in blood (it gives blood its red color). It preferentially absorbs wavelengths from argons, and to a lesser extent from rubies, alexandrites, and diodes. It minimally absorbs the Nd:YAG laser wavelength. Hemoglobin is not a primary target for laser hair removal.
  
• Melanin is considered the primary chromophore for all hair removal lasers currently on the market. Melanin occurs naturally in the skin (it gives skin and hair its color). There are two types of melanin in hair: eumelanin (which gives hair brown or black color) and pheomelanin (which gives hair blonde or red color). Because of the selective absorption of photons of laser light, only black or brown hair can be removed.
  

Any laser light beam intended for topical use can only penetrate skin tissue two millimeters deep. As such, there has been great controversy surrounding the laser industry claims to what most people think of when they hear the word "permanent".

The dermal papilla is the only appropriate target of destruction, as it is the only substructure of the hair shaft which can reproduce a new root system, and therefore a new hair shaft. The dermal papilla is located at a depth of 7-8 millimeters for coarse hair, and so is beyond the reach of laser.

For a short list of approved lasers, the Food and Drug Administration permits the use of the phrase "permanent reduction." The use of the phrase "permanent removal" is not permitted for any laser whatsoever. Clinics performing laser hair removal usually recommend at least six treatments. For this reason treatments are often sold in packages.

Laser hair removal costs

The costs of laser hair removal vary by region. The US average price for laser treatments is $429.00 according to the American Society of Plastic Surgeons.