Laser hair removal

 

The tone or style of this article or section may not be appropriate for Wikipedia. Specific concerns may be found on the talk page. See Wikipedia's guide to writing better articles for suggestions.

Epilation performed 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. Excellent reviews of laser hair removal methods, safety, and efficacy have been published in the dermatology literature.^[3][4][5]Wanner, M., Laser hair removal. Dermatol Ther, 2005. 18(3): p. 209-16.^[6]Alexiades-Armenakas, M., Laser hair removal. J Drugs Dermatol, 2006. 5(7): p. 678-9.^{[7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18]}

^[19]

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 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, chest, arms, legs, hands, and toes.

Laser is attracted to dark pigment and therefore 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.

Hair removal lasers have been in use since 1997 and the Food and Drug Administration approved it for “permanent reduction.” They permanently disable hair follicles, however you have to remember that laser hair removal doesn’t work in the same way on everyone and doesn’t remove 100% of the hair in an area. Generally, this means that you shouldn’t expect to remove every single hair from an area, although you can remove the majority of it (given you are a good candidate with light/medium skin and dark at least somewhat coarse hair). Most people need to follow up with electrolysis treatments for any remaining hairs to achieve complete clearance, if desired, as the remaining hairs become too sparse and fine for laser to target. Some will also need touch-up treatments about once a year, especially on large areas, after the initial set of 6-8 treatments for any new growth your body may develop with age on certain areas. 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. Keep in mind that it's hard to judge whether someone’s lack of results is due to a potential underlying medical condition that causes continuous growth and makes it seem like laser isn’t working, if the treatment wasn't performed properly, or whether for some people it just doesn't work for currently unknown reasons. In essence, you can’t determine what your personal results would be like unless you try it. Results depend on many variables involved, including the tech's experience, type of laser used, how settings are set, etc. It is recommended to start with one smaller area and see how your hair reacts before committing to an expensive set of treatments on many areas at once.

Electrolysis is an alternative permanent hair removal method that has been used for over 135 years. It involves treating one hair at a time and is a good option for smaller areas (like eyebrows or upper lip) where precision is necessary. It does take considerably more treatments compared to laser to complete a large area, but is an option as well. At this time, it is as the only permanent option for very fine and light-colored hair.

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 (not used for hair removal anymore)
• Ruby: 694 nm (not used for hair removal anymore; not safe on most skin types)
• 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)

Pulsewidth is an important consideration. It has been observed in some published studies that longer pulsewidths may be safer for darker skin. However, 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.

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
• Cryogen spray: immediately before/after the laser pulse
• Air cooling: forced cold air at -34 degrees C (Zimmer Cryo 5 unit)

Multiple treatments, usually 6-8, have been shown in numerous studies to provide long-term reduction of hair. Current parameters suggest a series of treatments spaced at 8-12 weeks apart for most areas, with face requiring shortest intervals and legs and back requiring longest intervals. These parameters are based on length of hair growth cycles on various areas.

Number of sessions

The number of sessions depends on various parameters, including the area of the body treated, skin color, coarseness of hair, and gender. In addition, since hair grows in several phases and laser can only affect the currently actively growing follicles, several sessions are needed to kill hair in all phases of growth.

In general, it is necessary to foresee between 6 and 8 sessions. 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 and men's backs, upper arms, and shoulders) may require considerably more treatments to achieve desired results.

It's important to note that laser does not work on light hair and very fine and vellus hair. Electrolysis is the only permanent solution for those types of hair.

Intervals between sessions

Usually, treatments are spaced 4-12 weeks apart to start, and often can gradually move to 10-16 weeks apart after the initial 2-3 treatments, 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.

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.

Cost

The costs of laser hair removal vary by region. The US average price for laser treatments is $229.00 according to the American Society of Plastic Surgeons.

Risks

The use of large quantities of high potency topical anesthetics to large surface areas of the skin, particularly when applied under occlusion, such as under plastic wrap, may result in lidocaine toxicity and resulting arrhythmias, and is contraindicated. According to published reports, two women completely coated their legs in topical anesthetic cream while at home and then suffered a toxic reaction on their way to the laser clinics, which led to coma and then death.^[20]Risks include the chance of burning the skin or discoloring dark skin with the laser, hypopigmentation (white spots), and flare of acne. Lack of proper government regulations in many countries means that patients are at risk of being treated by not properly trained staff.^[21]

Relative contraindications

Laser hair removal should be used cautiously, if at all, by patients in the following categories: Recently acquired dark tan; fine, light hair in people of color; blonde or red hair in areas with tan skin; patients who cannot afford or do not have the time for multiple sessions, because one treatment is rarely adequate.^[22]

References

See also

• Hair removal

External links

• Laser Facts (US Food and Drug Administration)
• American Academy of Dermatology, Public Resource Center, Laser Hair Removal
• American Society for Dermatologic Surgery: search for: "Laser Hair Removal Fact Sheet"
• American Society for Laser Medicine and Surgery
• Permanent hair removal by normal-mode ruby laser, from the Archives of Dermatology

Donate to Wikimedia