One of the problems with hair is—it doesn’t always grow in places where you want it to grow. So what do you do about unwanted hair?

There are two general categories of treatments for unwanted hair:

• Temporary—Shaving, plucking, waxing, bleaching, and removal of hair with a chemical depilating agent.
• Long-term or permanent—Laser thermolysis to destroy hair follicles and make them incapable of growing new hair or electronic destruction of hair follicles (electrolysis).

Long-Term and Permanent Hair Removal by Laser

Laser hair removal has been in use less than ten years and new applications are still being developed by researchers. Both men and women have found benefit from laser hair removal. Women most commonly seek hair removal in facial areas, and on the legs or arms. Men have increasingly found laser hair removal beneficial for excessive hair on the chest, shoulders and back. Lasers are well adapted to treating large surface areas, making laser treatment an excellent and more permanent alternative to waxing and other conventional removal methods.

A dermatologist or dermatologic surgeon trained and experienced in laser hair removal is best qualified to select and apply the correct laser wavelength in the individual patient. (Click on Choosing a Dermatologist for criteria to use and questions to ask when selecting a dermatologist). Today, many non-physicians are performing various cosmetic procedures outside their scope of training in spas, shopping malls and walk-in clinics. While these locations may offer some convenience to consumers, the supervision of the person performing the procedure, as well as the training and equipment available to handle complications or medical emergencies, can jeopardize the health and appearance of the patient.

The principle of laser hair removal is photothermolysis—using laser energy to generate heat inside a hair follicle to destroy its ability to grow new hair. Two responses are believed to occur in the hair follicle after a laser treatment: (1) immediate inhibition in growth of hair that is in active growth phase, and (2) long-term inhibition of new hair growth.

Lasers of various wavelengths are used to accomplish photothermolysis at chosen depths in the skin and in skin of various colors. After careful evaluation, the dermatologic surgeon selects the type of laser, laser energy, and duration of laser pulses to be used for the individual patient.

Laser energy is absorbed by the pigment that gives hair its color—eumelanin for brown and black hair, pheomelanin for red hair. Red and near-infrared laser light, for example, is strongly absorbed by brown or black hair, while red hair absorbs very little infrared light. The energy of the absorbed laser light is released as heat inside the hair follicle, creating the photothermal contact that damages or destroys the target tissue in the follicle. It is important that the correct laser is used for hair removal -- for example, the excimer laser produces a beam of very short wavelength that has very little skin penetration but is an excellent instrument to treat "surface" conditions such as atopic dermatitis, while the Nd:YAG laser produces a beam with very great skin penetration that can reach deep skin structures such as hair follicles.

Skin color also influences the absorption of laser light—e.g., pigmented skin tends to absorb more of the red to infrared laser wavelengths, while fair skin absorbs less of these laser wavelengths. As such, skin color must be taken into consideration when lasers are used in hair removal. Newer lasers such as the diode laser and Nd:YAG laser penetrate skin with little surface scattering of the laser beam, thus targeting the hair follicle more precisely and avoiding interaction with melanin in the skin. This is especially important in treatment of people with darker-colored skin, in whom some pigment changes may be noted after laser treatment.

Studies by dermatologic researchers indicate that laser hair removal is a procedure of choice for selected patients. Some studies have shown significant hair reduction after three to six laser treatments.

Side effects of laser treatment may include a feeling of stinging and burning pain similar to sunburn, and post-treatment redness and swelling in treated areas of skin. When laser energy is absorbed, the energy is released under the skin as heat. This heat is the source of sunburn-like stinging, and the tissue damaged by heat (thermolysis) reacts with redness and swelling. Some darker-colored skin has had temporary changes in pigmentation after laser treatment. Reports of post-treatment scarring are rare when performed by a dermatologic surgeon. However, there are increasing reports of scars from laser hair removal by non-physicians.

The patient’s eyes must be shielded during laser treatment to prevent any accidental direct or reflected laser energy from damaging the eyes.

While the laser methods of hair reduction discussed here are highly effective, no method, including older methods like electrolysis, is 100 percent effective in permanently removing all unwanted hair. There may be some hair regrowth and retreatments may be necessary in some patients.

References

Dierickx CC. Hair removal by lasers and intense pulsed sources. Semin Cutan Med Surg 2000; 19:267-275.

Hobbs L, Ort R, Dover J. Synopsis of laser assisted hair removal systems. Skin Therapy Lett 2000; 5:1-5.

Lou WW, Quintana AT, Geronemus RG, Grossman MC. Prospective study of hair reduction by diode laser (800 nm) with long-term follow-up. Dermatol Surg 2000; 26:428-432.