Laser hair removal
Epilation by laser was performed experimentally for about 20 years before it became commercially available in the mid 1970s. 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.
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.
Mechanism of action
The primary principle behind laser hair removal is selective photothermolysis (SPTL). 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.
Because of the selective absorption of photons of laser light, only black or brown hair can be removed. 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.
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 nm (DeepSkyBlue) or 514.5 nm (Cyan) (no longer used for hair removal)|
|Ruby laser: 694.3 nm (OrangeRed) (no longer used for hair removal; only safe for patients with very pale skin) |
|Alexandrite: 755 nm (Red) (most effective on pale skin and not safe on darker skin at effective settings)|
|Pulsed diode array: 810 nm (Near-Infrared) (for pale to medium type skin)|
|Nd:YAG laser: 1064 nm (Near-Infrared) (made for treating darker skin types, though effective on all skin types)|
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 heat up the follicles enough to disable them from producing hair.
Epidermal cooling has been determined to allow higher fluences and reduce pain and side effects, especially in darker skin.
Number of sessions
Multiple treatments (typically 6-8 spaced 8-12 weeks apart) depending on the type of hair and skin color have been shown to provide long-term reduction of hair. Current parameters suggest a series of treatments spaced at 8-12 weeks apart for based on typical hair cycle patterns for each area.
The number of sessions depends on various parameters, including the area of the body treated, skin color, coarseness of hair, reason for hirsutism, and sex. Coarse dark hair on light skin is easiest to treat. Hair on darker skin is harder to treat. Finer hair is only sometimes affected. Certain areas (notably men'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.
Intervals between sessions
Usually treatments are spaced 8–12 weeks apart depending on the body area and the hair cycle length for that area. For example, faces usually require more frequent treatments, whereas legs require less frequent treatments.
Instead of following an arbitrary schedule, one should wait until they have experienced shedding of the treated hairs, which should complete within 2-3 weeks, and see enough hair come in after the hair-free period to have another treatment. It's advisable to do a touchup if significant amount of hair hasn't shed within 3 weeks.
Side effects and risks
Some normal side effects may occur after laser hair removal treatments, including itching, redness and swelling around the treatment area. These side effects should not last more than three days. Some level of pain should also be expected during treatments. Numbing creams are available at most clinics, usually for an additional cost. Icing the area after the treatment helps relieve the side effects faster.
Unwanted side effects such as hypo- or hyper-pigmentation or, in extreme cases, burning of the skin call for an adjustment in laser settings. Risks include the chance of burning the skin  or discoloration of the skin, hypopigmentation (white spots), flare of acne, swelling around the follicle, scab forming, purpura, and infection. These risks can be avoided when being treated at with an appropriate laser type and at appropriate settings for the individual's skin type.
Some patients may show side effects from an allergy to either the hair removal gel used with certain laser types or to a numbing cream. A physician should be consulted if an allergic reaction presents itself after the treatment.
Comparison with electrolysis
Electrolysis is another hair removal method that has been used for over 135 years. 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.
- Dierickx, C.C., et al., Permanent hair removal by normal-mode ruby laser. Arch Dermatol, 1998. 134(7): p. 837-42.
- Gold MH. Lasers and light sources for the removal of unwanted hair.Clin Dermatol. 2007 Sep-Oct;25(5):443-53.
- Eremia, S., et al., Laser hair removal: long-term results with a 755 nm alexandrite laser. Dermatol Surg, 2001. 27(11): p. 920-4.
- The matching of a specific wavelengh of light and pulse duration to obtain optimal effect on a targeted tissue with minimal effect on surrounding tissue
- Laser Hair Removal Complications
- Can I Sunbathe Before or After Laser Hair Removal?
- Michel CE. Trichiasis and distichiasis; with an improved method for radical treatment. St. Louis Clinical Record, 1875 Oct; 2:145-148
- Görgü M, Aslan G, Aköz T, Erdoğan B (January 2000). "Comparison of alexandrite laser and electrolysis for hair removal". Dermatol Surgery 26 (1): 37–41. doi:10.1046/j.1524-4725.2000.99104.x. PMID 10632684.
- 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"
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