Epilation by laser was performed experimentally for about 20 years before it became commercially available in the mid 1990s. Intense Pulsed Light (IPL) epilators, though technically not a laser, use xenon flash lamps that emit full spectrum light. Laser and light-based methods, sometimes called phototricholysis or photoepilation, are now most commonly referred to collectively as "laser hair removal". One of the first published articles describing laser hair removal was authored by the group at Massachusetts General Hospital in 1998.^[1][2]

The efficacy of laser hair removal is now generally accepted in the dermatology community, and laser hair removal is widely practiced. Many reviews of laser hair removal methods, safety, and efficacy have been published in the dermatology literature.^[3]

Contents 1 Mechanism of action 2 Comparison with electrolysis 3 Laser parameters that affect results 4 Number of sessions 5 Intervals between sessions 6 Other uses 7 Side Effects & Risks 8 See also 9 References 10 Notes 11 External links

[edit] Mechanism of action

The primary principle behind laser hair removal is selective photothermolysis (SPTL).^[4] Lasers can cause localized damage by selectively heating dark target matter, (melanin), in the area that causes hair growth, (the follicle), 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 melanin:

• 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.

Both men and women seek laser hair removal services to have superfluous or unwanted hair removed. Hair removal is commonly done on lip, chin, ear lobe, shoulders, back, underarm, abdomen, buttocks, pubic area, bikini lines, thighs, face, neck, cleavage, chest, arms, legs, hands, and toes.

Laser works best with dark coarse hair. Light skin and dark hair are an ideal combination, but new lasers are now able to target dark black hair even in patients with dark skin.^{[citation needed]}

Hair removal lasers have been in use since 1997 and has been approved for "permanent hair reduction" in the United States by the Food and Drug Administration (FDA).^{[citation needed]} Laser hair removal has become extremely popular because of its speed and efficacy, although some of the efficacy is dependent upon the skill and experience of the laser operator, and the choice and availability of different laser technology at the clinic which is performing the procedure. Some will need touch-up treatments, especially on large areas, after the initial set of 3-8 treatments. It has also been observed that some people seem to be non-responders – this is not confirmed and reasons are not known, and may in fact be due to lack of skill on the part of many laser operators and/or the type of machine and settings they are using.^{[citation needed]}

[edit] Comparison with electrolysis

Electrolysis is another hair removal method that has been used for over 135 years.^[5] At this time, it is the only permanent option for very fine and light-colored hair. The FDA currently allows the term "Permanent Hair Removal" for electrolysis only. Unlike laser epilation, electrolysis is effective on all hair colors.

A study conducted in 2000 at the ASVAK Laser Center in Ankara, Turkey comparing alexandrite laser and electrolysis for hair removal on 12 patients concluded that laser hair removal was 60 times faster, less painful and more reliable than electrolysis.^[6]

[edit] Laser parameters that affect results

Several wavelengths of laser energy have been used for hair removal, from visible light to near-infrared radiation. These lasers are usually defined by the lasing medium used to create the wavelength (measured in nanometers (nm)):

• Argon: 488 or 514.5 nm (no longer used for hair removal)
• Ruby: 694 nm (no longer used for hair removal; not safe on most skin types as it frequently produces side effects such as pigmentary changes (lightening or darkening of the skin) or worse for patients of all but white skin.^{[citation needed]}
• Alexandrite: 755 nm (most effective, but safest on light skin)
• Pulsed diode array: 810 nm (for light to medium type skin)
• Nd:YAG: 1064 nm (for darker skin; Yag is capable of treating all six skin colors. However, there is not sufficient evidence that this laser can produce effective long-term hair removal)

Pulsewidth is an important consideration. It has been observed in some published studies that longer pulse widths may be safer for darker skin. Shorter wavelengths may be more effective in removing hair.

Spot size, or the width of the laser beam, affects treatment. Theoretically, the width of the ideal beam is about four times as wide as the target is deep. Hair removal lasers have a round spot about the size of your finger (8-18 mm). Larger spot sizes help make treatments faster and more effective.

Fluence or energy level is another important consideration. Fluence is measured in joules per square centimeter (J/cm²). It's important to get treated at high enough settings to cause permanent damage to the hair follicles.

Repetition rate is believed to have a cumulative effect, based on the concept of thermal relaxation time. Shooting two or three pulses at the same target with a specific delay between pulses can cause a slight improvement in the heating of an area. This may increase the "kill rate" for each treatment slightly.

Epidermal cooling has been determined to allow higher fluences and reduce pain and side effects, especially in darker skin. Four types of cooling have been developed:

• Clear gel: usually chilled
• Contact cooling: through a window cooled by circulating water or internal cryogen.
• Cryogen spray: immediately before/after the laser pulse
• Air cooling: forced cold air at -34 degrees C (Zimmer Cryo 5 unit)

[edit] Number of sessions

Multiple treatments, usually 5-7, but as many as 12, depending on the type of hair and skin color have been shown in practice to provide long-term reduction of hair. Current parameters suggest a series of treatments spaced at 4–6 weeks apart for most areas, although the timing of treatments has still not been standardized.^[7]

The number of sessions depends on various parameters, including the area of the body treated, skin color, coarseness of hair, and sex. Coarse dark hair on light skin is easiest to treat. Finer hair and hair on darker skin is harder to treat and may require more treatments. Certain areas (notably men's and women's faces) may require considerably more treatments to achieve desired results. In addition, since hair grows in several phases, (anagen, telogen, catagen), and laser can only affect the currently active growing follicles, (anagen), several sessions are needed to kill hair in all phases of growth.

It's important to note that laser does not work on light hair and very fine and vellus hair ("peachfuzz"). Laser hair removal is not permanent but it is long term and can be patchy. Electrolysis is the only permanent solution for those types of hair but has shortcomings such as possible scarring, expense, and discomfort, as noted above.

[edit] Intervals between sessions

Usually, treatments are spaced 3–12 weeks apart to start, although the spacing depends upon individual response to treatment. Instead of following an arbitrary schedule, you should wait until you have experienced shedding of the treated hairs, which should complete within 2-3.5 weeks, and see enough hair come in after the hair-free period to have another treatment. Treatment spacing also depends on area treated as hair cycles vary based on the body part. For example, women’s faces usually require more frequent treatments, whereas backs and legs require less frequent treatments.

[edit] Other uses

Hair removal lasers are effective treatment for pseudofolliculitis barbae (commonly called ingrown hairs or "shaving bumps"). For darker skin patients with black hair, the long-pulsed Nd:YAG laser with a cooling tip can be safe and effective when used by an experienced practitioner.

They have recently been reported as helpful treatment for pilonidal cysts, since they eliminate the ingrown hairs that produce the troublesome foreign body reactions in this congenital malady.

[edit] Side Effects & Risks

As laser hair removal is done while causing localized damage to the skin around the follicle of the hair, it is absolutely normal that the treatment comes with some unwanted side effects. Normal side effects are itching, redness and swelling around the treatment area. Some level of pain, tingling and numbness is considered to be expected as well. ^[8] These side effects caused by the hair removal treatment should not last more than three days.

Risks include the chance of burning the skin ^[9] or discoloring dark skin with the laser, hypopigmentation (white spots), flare of acne, ^[10] swelling around the follicle, scab forming, and purpura. Another serious risk of laser hair removal is infection.

[edit] See also

• Hair removal

[edit] References

• Liew, S.H., Laser hair removal: guidelines for management. Am J Clin Dermatol, 2002. 3(2): p. 107-15.
• Aldraibi, M.S., D.J. Touma, and A. Khachemoune, Hair removal with the 3-msec alexandrite laser in patients with skin types IV-VI: efficacy, safety, and the role of topical corticosteroids in preventing side effects. J Drugs Dermatol, 2007. 6(1): p. 60-6.
• Wanner, M., Laser hair removal. Dermatol Ther, 2005. 18(3): p. 209-16.
• Goldberg, D.J., Laser- and light-based hair removal: an update. Expert Rev Med Devices, 2007. 4(2): p. 253-60.
• Alexiades-Armenakas, M., Laser hair removal. J Drugs Dermatol, 2006. 5(7): p. 678-9.
• Alexiades-Armenakas, M., Laser hair removal. J Drugs Dermatol, 2006. 5(7): p. 678-9.
• Bjerring, P., et al., Evaluation of the free-running ruby laser for hair removal. A retrospective study. Acta Derm Venereol, 1998. 78(1): p. 48-51.
• Dierickx, C.C., Grossman, M.C., Farinelli, W.A., Anderson, R.R. Permanent hair removal by normal-mode ruby laser. Arch Dermatol, 1998. 134(7): p. 837-42.
• Eremia, S., et al., Laser hair removal: long-term results with a 755 nm alexandrite laser. Dermatol Surg, 2001. 27(11): p. 920-4.
• Goldberg, D.J., Laser- and light-based hair removal: an update. Expert Rev Med Devices, 2007. 4(2): p. 253-60.
• Kelly, K.M., L.O. Svaasand, and J.S. Nelson, Further investigation of pigmentary changes after alexandrite laser hair removal in conjunction with cryogen spray cooling. Dermatol Surg, 2004. 30(4 Pt 1): p. 581-2.
• Liew, S.H., Laser hair removal: guidelines for management. Am J Clin Dermatol, 2002. 3(2): p. 107-15.
• McDaniel, D.H., et al., Laser hair removal: a review and report on the use of the long-pulsed alexandrite laser for hair reduction of the upper lip, leg, back, and pelvic region. Dermatol Surg, 1999. 25(6): p. 425-30.
• Nanni, C.A. and T.S. Alster, Long-pulsed alexandrite laser-assisted hair removal at 5, 10, and 20 millisecond pulse durations. Lasers Surg Med, 1999. 24(5): p. 332-7.
• Sadick, N.S., Laser hair removal. Facial Plast Surg Clin North Am, 2004. 12(2): p. 191-200.
• Yee, S., Laser hair removal in Fitzpatrick type IV to VI patients. Facial Plast Surg, 2005. 21(2): p. 139-44.
• Wanner, M., Laser hair removal. Dermatol Ther, 2005. 18(3): p. 209-16.
• Warner, J., M. Weiner, and K.A. Gutowski, Laser hair removal. Clin Obstet Gynecol, 2006. 49(2): p. 389-400.

[edit] Notes

[edit] External links

• Laser Facts (US Food and Drug Administration)
• Additional Information on Removing Hair Safely
• American Academy of Dermatology, Public Resource Center, Laser Hair Removal
• American Society for Dermatologic Surgery: "Laser Hair Removal Fact Sheet"
• American Society for Laser Medicine and Surgery
• Laser Hair Removal Information by Laser Clinics UK
• Laser Hair Removal Information by Laser Clinics Australia