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Laser Hair Removal

Laser Hair Removal

Article Author:
Tanvi Vaidya
Article Author:
Marc Hohman
Article Editor:
Dinesh Kumar D
8/23/2020 9:07:58 PM
For CME on this topic:
Laser Hair Removal CME
PubMed Link:
Laser Hair Removal


The demand for safe, long-lasting, and effective hair reduction for aesthetic as well as medical indications is on the rise. A variety of options for hair removal are available, such as epilation by plucking or waxing, depilation by shaving, chemical depilatories, electrolysis, eflornithine cream, and laser and intense pulsed light (IPL) systems. A variety of lasers and IPL systems are available and are the most effective options for long-term hair reduction.[1] The mechanism of action of these systems is the targeting melanin in the hair shaft, follicular epithelium, and hair matrix by emitting light with wavelengths ranging from 600 to 1200 nanometers (nm), because those wavelengths are selectively absorbed by melanin.[2]

Anatomy and Physiology

Selective Photothermolysis

Lasers for skin treatment work on the theory of "selective photothermolysis." This term implies a site-specific, thermally mediated injury of microscopic tissue targets by the selective absorption of pulses of radiation by the targets and the chromophores. The natural or artificial chromophores absorb monochromatic or broadband electromagnetic radiation of specific wavelengths. The chromophore employed in laser hair reduction is melanin. Melanin absorbs light in the range of 300 to 1200 nm, and lasers in this range of wavelengths can be effectively used for hair reduction.[3][4]

An Extended Theory of Selective Photothermolysis

Target absorption may not always be uniform. In these cases, the weakly absorbing parts may have to be destroyed by heat diffusion from the highly absorbing parts. This is the "extended theory of selective photothermolysis." This principle is applied to laser photoablation. Melanin content is much higher in melanin-bearing structures like the hair shaft and matrix cells than in the hair follicle. Thus melanin captures energy from the laser and distributes it to the surrounding follicular structures. This results in the destruction of the hair matrix and hair bulge stem cells.[5]


  1. Hirsutism and hypertrichosis
  2. Aesthetic purposes
  3. Medical indications like pseudofolliculitis barbae, pilonidal sinus, and acne keloidalis nuchae.[6]


Lasers for hair reduction include the following:

  1. Ruby Laser (694 nm) - Red light is delivered through synthetic ruby crystals, more effective for lighter skin types with dark hair (skin types I-III*)[7]
  2. Alexandrite Laser (755 nm) - Greater penetrance, good for lighter hair (skin types I-III)[8]
  3. Diode Laser (810 nm) - Penetrates deeper, delivers better fluence, less epidermal damage, safer in darker skin (skin types I-V)[9]
  4. Neodymium-doped Yttrium-Aluminium-Garnet (Nd: YAG) Laser (1064 nm) - Better penetration, less epidermal damage, relatively less melanin absorption (skin types I-VI)[10]
  5. Intense Pulse Light (IPL) or Broadband Light (BBL) (500-1200 nm) - High-intensity pulses of polychromatic, non-coherent light are delivered by a flash-lamp; various filters allow the narrowing of the emitted wavelength band, can be used on darker skin, larger areas can be covered due to its larger spot size, less expensive than a true laser but not as effective[11][12][13]

* Fitzpatrick Skin Types[10]

  • I- Pale white skin, blue/green eyes, blond/red hair; always burns, does not tan
  • II- Fair skin, blue eyes; burns easily, tans poorly
  • III- Darker white skin; tans after the initial burn
  • IV- Light brown skin; burns minimally, tans easily
  • V- Brown skin; rarely burns, tans darkly easily
  • VI- Dark brown or black skin; never burns, always tans darkly


  1. Detailed clinical history to rule out infections, drug intake, etc.
  2. Hormonal evaluation to assess causes of hirsutism.
  3. Counsel the patient to manage expectations. It must be stressed that the procedure provides permanent hair reduction rather than removal.
  4. Evaluate skin and hair types to choose the right laser and parameters.
  5. Avoid hair epilation by plucking or waxing for 6 weeks before the procedure.
  6. Sunscreens may be prescribed 4 to 6 weeks before the procedure, especially on exposed areas.
  7. Pre-procedure photographs, with due consent, to maintain a record for evaluation of treatment response.
  8. Shave the area long enough before the procedure to allow a slight stubble to develop; this will provide enough of a target for the laser without absorbing too much energy in the hair shaft itself.
  9. Obtain an informed consent.
  10. If need be, a topical anesthetic cream may be applied one-half to one hour before the procedure.[14][15]


  1. Clean the area to remove oils from the skin
  2. Position the patient comfortably.
  3. Use eye protection for both the operator and the patient.
  4. Avoid reflecting surfaces or metallic objects near the laser.
  5. Individualize the parameters to each patient's skin and hair type and the type of laser being used. 
  6. Place the handpiece perpendicular to the skin. Ensure that it is pressed down gently but firmly to bring the follicles close to the surface and temporarily decrease the blood supply to the treatment area.
  7. Perifollicular edema and erythema is an expected side effect, and this must be explained to the patient prior to the procedure.[14][15]

Post-Procedure Care

  1. Although most machines have inbuilt cooling systems, ice packs or cooling agents may be used post-procedure to minimize pain and swelling.
  2. In case of inadvertent epidermal injury, topical antibiotics may be used.
  3. Strict sun protection and the use of sunscreens is a must.
  4. Topical steroid creams may be prescribed to minimize erythema and swelling.[14][11]

The hair matrix is only sensitive to laser treatment during the anagen phase of the hair growth cycle; therefore multiple treatments will be necessary in order to address all hair follicles when they are most sensitive to treatment. In the initial phase of hair removal therapy, 4 to 6 sessions spaced 4 to 6 weeks apart are the minimum required to achieve adequate results. Subsequently, patients may need maintenance treatments once every 6 to 12 months as small vellus hair may grow back.[16]

Various factors may affect the outcome, such as:

  1. Hair location (axillary and pubic hair respond better than hair on the extremities and chest)
  2. Skin and hair color (light skin of Fitzpatrick skin types I-IV with dark hair achieve the best results due to the lack of melanin in the skin and the abundance of melanin to absorb laser energy in the hair follicles)
  3. Hair growth stage (anagen hair being most sensitive)
  4. Laser type
  5. Hormonal status
  6. Treatment plan[2]


Adjacent epidermal structures other than melanin within the hair bulb can compete for absorption, and may cause laser energy to be absorbed by pigment in the epidermis. This hampers the effectiveness of the treatment and causes adverse effects due to adjacent epithelial damage. [17]

Common adverse effects of laser or IPL-based hair removal include post-treatment erythema, pain, and burning.[18]

More severe adverse effects include blistering, crusting, dyspigmentation, purpura, and sometimes scarring.[19][20] Ocular complications due to accidental injury may be seen. Paradoxical hypertrichosis may rarely occur, more commonly in skin type III and with the use of IPL systems.[21][22][23]

Clinical Significance

Selecting the correct lasers with the appropriate parameters, individualized to each patient, is very important, particularly in patients with intrinsically dark skin. Most complications are preventable when adequate precautions are taken with adjustment of the fluence, spot size, wavelength, and the use of appropriate cooling. Thus, it is all the more important that trained personnel with a thorough knowledge of the mechanisms, techniques, and complications carry out these procedures.

Enhancing Healthcare Team Outcomes

Laser hair removal is performed by many healthcare workers including nurses, dermatologists, plastic surgeons, primary care providers and other cosmetic surgeons. Unfortunately, because of lack of oversight, complications are common during this procedure. To make matters worse, patients are often given unrealistic expectations. The key is to use the correct laser, especially in dark skinned individuals. Common adverse effects of laser or IPL-based hair removal include post-treatment erythema, pain, and burning.[18] More severe adverse effects include blistering, crusting, dyspigmentation, purpura, and sometimes, scarring.[19][20] Ocular complications due to accidental injury may be seen. Paradoxical hypertrichosis may rarely occur, more commonly in skin type III and with the use of IPL systems.[21][22][23]

Overall, lasers can remove hair but rarely does the procedure provide a permanent cure for hair growth. Touch up maintenance treatments are required for most patients in the long term.


[1] Evidence-based review of hair removal using lasers and light sources., Haedersdal M,Wulf HC,, Journal of the European Academy of Dermatology and Venereology : JEADV, 2006 Jan     [PubMed PMID: 16405602]
[2] 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 bikini region., McDaniel DH,Lord J,Ash K,Newman J,Zukowski M,, Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 1999 Jun     [PubMed PMID: 10469087]
[3] Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation., Anderson RR,Parrish JA,, Science (New York, N.Y.), 1983 Apr 29     [PubMed PMID: 6836297]
[4] Laser-assisted hair removal by selective photothermolysis. Preliminary results., Lask G,Elman M,Slatkine M,Waldman A,Rozenberg Z,, Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 1997 Sep     [PubMed PMID: 9311365]
[5] Extended theory of selective photothermolysis., Altshuler GB,Anderson RR,Manstein D,Zenzie HH,Smirnov MZ,, Lasers in surgery and medicine, 2001     [PubMed PMID: 11891730]
[6] Laser hair removal., Goldberg DJ,, Dermatologic clinics, 2002 Jul     [PubMed PMID: 12170888]
[7] Permanent hair removal by normal-mode ruby laser., Dierickx CC,Grossman MC,Farinelli WA,Anderson RR,, Archives of dermatology, 1998 Jul     [PubMed PMID: 9681347]
[8] Alexandrite laser hair removal is safe for Fitzpatrick skin types IV-VI., Garcia C,Alamoudi H,Nakib M,Zimmo S,, Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 2000 Feb     [PubMed PMID: 10691941]
[9] Prospective study of hair reduction by diode laser (800 nm) with long-term follow-up., Lou WW,Quintana AT,Geronemus RG,Grossman MC,, Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 2000 May     [PubMed PMID: 10816229]
[10] Nd:YAG laser hair removal in Fitzpatrick skin types IV to VI., Chan CS,Dover JS,, Journal of drugs in dermatology : JDD, 2013 Mar     [PubMed PMID: 23545924]
[11] Hair removal with a non-coherent filtered flashlamp intense pulsed light source., Weiss RA,Weiss MA,Marwaha S,Harrington AC,, Lasers in surgery and medicine, 1999     [PubMed PMID: 10100650]
[12] Hair removal using a pulsed-intense light source., Tse Y,, Dermatologic clinics, 1999 Apr     [PubMed PMID: 10327304]
[13] Long-term photoepilation using a broad-spectrum intense pulsed light source., Sadick NS,Weiss RA,Shea CR,Nagel H,Nicholson J,Prieto VG,, Archives of dermatology, 2000 Nov     [PubMed PMID: 11074695]
[14] A practical review of laser-assisted hair removal using the Q-switched Nd:YAG, long-pulsed ruby, and long-pulsed alexandrite lasers., Nanni CA,Alster TS,, Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 1998 Dec     [PubMed PMID: 9865211]
[15] Lasers in dermatology: four decades of progress., Tanzi EL,Lupton JR,Alster TS,, Journal of the American Academy of Dermatology, 2003 Jul     [PubMed PMID: 12833005]
[16] Damage to hair follicles by normal-mode ruby laser pulses., Grossman MC,Dierickx C,Farinelli W,Flotte T,Anderson RR,, Journal of the American Academy of Dermatology, 1996 Dec     [PubMed PMID: 8959946]
[17] Side effects and complications of laser therapy., McBurney EI,, Dermatologic clinics, 2002 Jan     [PubMed PMID: 11859590]
[18] Hair removal by lasers and intense pulsed light sources., Dierickx CC,, Dermatologic clinics, 2002 Jan     [PubMed PMID: 11859588]
[19] Laser-assisted hair removal: side effects of Q-switched Nd:YAG, long-pulsed ruby, and alexandrite lasers., Nanni CA,Alster TS,, Journal of the American Academy of Dermatology, 1999 Aug     [PubMed PMID: 10426883]
[20] Reticulate erythema following diode laser-assisted hair removal: a new side effect of a common procedure., Lapidoth M,Shafirstein G,Ben Amitai D,Hodak E,Waner M,David M,, Journal of the American Academy of Dermatology, 2004 Nov     [PubMed PMID: 15523357]
[21] Laser-assisted hair removal in Asian skin: efficacy, complications, and the effect of single versus multiple treatments., Hussain M,Polnikorn N,Goldberg DJ,, Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 2003 Mar     [PubMed PMID: 12614418]
[22] Laser therapy on darker ethnic skin., Battle EF Jr,Hobbs LM,, Dermatologic clinics, 2003 Oct     [PubMed PMID: 14717412]
[23] Paradoxical hypertrichosis after laser epilation., Alajlan A,Shapiro J,Rivers JK,MacDonald N,Wiggin J,Lui H,, Journal of the American Academy of Dermatology, 2005 Jul     [PubMed PMID: 15965427]