INVITED REVIEW ARTICLEdth_1382 94..107

Laser hair removalOmar A. Ibrahimi*,†, Mathew M. Avram‡, C. William Hanke§,Suzanne L. Kilmer† & R. Rox Anderson‡*Department of Dermatology, University of California Davis and †Laser andSkin Surgery Center of Northern California, Sacramento, California and‡Department of Dermatology, Massachusetts General Hospital, HarvardMedical School, Boston, Massachusetts and §Laser and Skin Surgery Centerof Indiana, Carmel, Indiana

ABSTRACT: The extended theory of selective photothermolysis enables the laser surgeon to target anddestroy hair follicles, thereby leading to hair removal. Today, laser hair removal (LHR) is the mostcommonly requested cosmetic procedure in the world and is routinely performed by dermatologists,other physicians, and non-physician personnel with variable efficacy. The ideal candidate for LHR is fairskinned with dark terminal hair; however, LHR can today be successfully performed in all skin types.Knowledge of hair follicle anatomy and physiology, proper patient selection and preoperative prepa-ration, principles of laser safety, familiarity with the various laser/light devices, and a thorough under-standing of laser–tissue interactions are vital to optimizing treatment efficacy while minimizingcomplications and side effects.

KEYWORDS: laser hair removal, photoepilation, selective photothermolysis

Introduction

History of laser hair removal

The ability of lasers to nonspecifically damage hairfollicles was noted nearly 50 years ago in the firstreports on the use of lasers on human skin (1,2).However, it was not until the theory of selectivephotothermolysis was proposed by Anderson andParrish at the Wellman Center for Photomedicine atHarvard Medical School, that the concept of selec-tively targeting a particular chromophore based onits absorption spectra and size was realized (3).Several years later, this group also reported the firstsuccessful use of a normal-mode ruby laser forlong-term and permanent hair removal (4,5).

Alternative methods for hair removal

Today, removing unwanted body hair is an increas-ingly prevalent trend in our society, and photoepi-lation by laser or other light-based technology isthe fastest-growing procedure in cosmetic derma-tology (6). Other methods for removing unwantedhair include bleaching, plucking, shaving, waxing,and chemical depilatories. Threading is a commonpractice in some cultures. None of these methodsprovide a permanent solution to unwanted hair,and can be inconvenient and tedious (7,8). Elec-trolysis is a method for hair removal in which a fineneedle deep into the hair follicle destroys thefollicle via electrical current, thus allowing for per-manent hair removal of both terminal and nonter-minal hair, as well as of both pigmented andnon-pigmented hair (9,10). However, this tech-nique is extremely operator dependent and efficacyin achieving permanent hair removal is variable

Address correspondence and reprint requests to: Omar A.Ibrahimi, MD, PhD, Department of Dermatology, Universityof California Davis, 3301 C Street, Suite 1400, Sacramento,California 95816, or email: omar.ibrahimi@gmail.com.

94

Dermatologic Therapy, Vol. 24, 2011, 94–107Printed in the United States · All rights reserved

© 2011 Wiley Periodicals, Inc.

DERMATOLOGIC THERAPYISSN 1396-0296

among patients (9,10). Thus, it is often impracticalin terms of treating large areas. Eflornithine is atopical inhibitor of ornithine decarboxylase thatslows the rate of hair growth and is effective forunwanted facial hair (8), and is currently indicatedfor the removal of unwanted facial hair in women.Eflornithine can be combined with lasers andintense pulsed light (IPL) for hair removal (11,12).

The hair follicle

Hair anatomy

The hair follicle is an intricate, hormonally activestructure with a programmed growth pattern(FIG. 1). It is anatomically divided into theinfundibulum (hair follicle orifice to insertion ofthe sebaceous gland), isthmus (insertion of thesebaceous gland to the insertion of the arrector pilimuscle), and inferior (insertion of the arrectorpili to the base of the hair follicle) segments. Thedermal papilla, a neurovascular structure that sup-plies the cells of the proliferating matrix at the baseof the follicle, helps form the hair shaft.

Hair growth

Each hair follicle consists of a permanent (upper)and nonpermanent (lower) part, with the follicularbulge forming the lowermost aspect of the perma-nent part. In periods of active growth (anagen) therapidly developing bulbar matrix cells differentiateinto the hair shaft and the hair lengthens. A transi-tion period follows in which the bulbar part of thehair follicle undergoes degradation through apop-tosis (catagen). A resting period (telogen) phaseensues, and regrowth is started once again in earlyanagen. Stem cells within the hair follicle regener-ate the follicle within or near the hair bulb matrix.Slow-cycling stem cells have also been found in thefollicular bulge arising off the outer root sheathat the site of arrector pili muscle attachment.The duration of each growth phase is body sitedependent.

Hair types

There are three main types of hair: lanugo, vellus,and terminal hairs. Lanugo hairs are fine hairs thatcover a fetus and are shed in the neonatal period.Vellus hairs are nonpigmented, and have a diam-eter of roughly 30 mm. Terminal hair shafts rangefrom 150 to 300 mm in cross-sectional diameter.The type of hair produced by an individual follicle

is capable of change (e.g., vellus to terminal hair atpuberty or terminal to vellus hair in androgenicalopecia).

Hair color

Hair color is determined by the amount of pigmentin the hair shaft. Melanocytes produce two typesof melanin: eumelanin, a brown-black pigment;and pheomelanin, a red pigment. Melanocytes arelocated in the upper portion of the hair bulb andouter root sheath of the infundibulum.

Classification of excess hair

Excessive and unwanted body hair ranges in sever-ity, depending on cultural mores, and can usually

FIG. 1. Hair follicle anatomy (reproduced from Tsao SS andHruza GJ. Laser hair removal. In: Robinson JK, Hanke CW,Sengelmann RD, and Siegel DM, eds. Surgery of The Skin.Philadelphia: Elsevier Mosby, 2005: 575–588).

Laser hair removal

95

be classified as either hypertrichosis or hirsutism(13). Hirsutism is defined as the abnormal growthof terminal hair in women in male-pattern(androgen-dependent) sites, such as the faceand chest. Hypertrichosis refers to excess hairgrowth at any body site that is not androgen-dependent (13).

Mechanism of LHR

The theory of selective photothermolysis enablesone to selectively target pigmented hair follicles byusing the melanin of the hair shaft as a chro-mophore (3). Melanin is capable of functioning as achromophore for wavelengths in the red and near-infrared portion of the electromagnetic spectrum(14). However, to achieve permanent hair removal,the biological “target” is likely the follicular stemcells located in the bulge region and/or dermalpapilla. Based on the slight spatial separation of thechromophore and desired target, an extendedtheory of selective photothermolysis was proposedwhich requires diffusion of heat from the chro-mophore to the desired target for destruction (15).This requires a laser pulse duration that is longerin duration than if the actual chromophore anddesired target were identical. Temporary LHR canresult when the follicular stem cells are not com-pletely destroyed, primarily through induction of acatagen-like state in pigmented hair follicles. Tem-porary LHR is much easier to achieve than perma-nent removal, using lower fluences. Long-term hairremoval depends on hair color, skin color, and tol-erated fluence. Roughly 15–30% long-term hairloss may be observed with each treatment whenoptimal treatment parameters are used (16). A listof laser and light devices that are commerciallyavailable at the time of this publication for hairremoval are summarized in Table 1.

Key factors in optimizing treatment

The ability to selectively target hair follicles withlasers and light sources has revolutionized theability to eliminate unwanted hair temporarily andpermanently in many individuals. As laser technol-ogy advances, the ability to treat individuals ofall skin types and all hair colors broadens.Proper patient selection, preoperative preparation,informed consent, understanding of the principlesof laser safety, and laser and light source selectionare key to the success of laser treatment. An under-standing of hair anatomy, growth and physiology,together with a thorough understanding of laser–

tissue interaction, in particular within the contextof choosing optimal laser parameters for effectiveLHR, should be acquired before using lasers forhair removal.

Patient selection

Despite the seemingly cosmetic nature of LHR, acomplete medical history, physical examinationand informed consent, including setting realisticpatient expectations and potentials risks, shouldbe preformed prior to any laser treatment. Anypatient with evidence for endocrine or menstrualdysfunction should be appropriately worked up.Similarly, patients with an explosive onset of hyper-trichosis should be evaluated for paraneoplasticetiologies. Treatment of a pregnant woman fornonurgent conditions is discouraged, althoughthere is no evidence suggesting a potential riskto pregnant women undergoing LHR. The pastmedical history should be reviewed to identifypatients with photosensitive conditions, such asthe autoimmune connective tissue disorders, ordisorders prone to the Koebner phenomenon. Ahistory of recurrent cutaneous infections at or inthe vicinity of treatment area might warrant the useof prophylactic medications. Any past history ofkeloid or hypertrophic scar formation should beelicited as well. Previous methods for hair removal,including any past laser treatments, should bereviewed. Any methods of epilation, such aswaxing or tweezing, that entirely remove the targetchromophore, render LHR ineffective for at least 2weeks. Although there is little evidence for the timeframe a patient must wait after complete epilationof the hair shaft and laser treatment, we recom-mend a minimum of 6 weeks. Shaving and depila-tory creams can be used up to the day of the lasertreatment as they do not remove the entire hairshaft.

A thorough medication history should beobtained. Any history of gold intake is a contrain-dication for laser therapy. The use of any photo-sensitizing medications or over-the-countersupplements should also delay treatment untilthese medications can be safely discontinued.There is controversy as to whether patients onisotretinoin should be treated with laser, althoughconventionally most practitioners recommend a6-month to 1-year washout period prior to lasertreatment (17–19). Topical retinoids used in thetreatment area should be discontinued 1–2 daysprior to treatment.

The physical exam should evaluate thepatient’s Fitzpatrick skin phototype. This will help

Ibrahimi et al.

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determine which lasers and light sources are safe touse for that patient (Table 1), because epidermalmelanin in darkly pigmented patients can competewith the melanin within hair follicles as the targetchromophore. Importantly, every patient shouldalways be evaluated for the presence of a tan, and ifpresent, laser treatment should be delayed or thetreatment parameters appropriately adjusted untilthe tan has faded. Finally, the patient’s hair colorshould be noted as the chromophore for LHR ismelanin. Black and brown hair contain sufficientamounts of melanin to serve as a chromophore forLHR. In contrast, the lack of melanin, paucity ofmelanin, or presence of eumelanin in the hair fol-licle, which clinically correlates to white, gray, orred/blonde hair, is predictive of a poor response tolaser hair removal. For patients with little to nomelanin in their hair follicles, attempts have beenmade to use an exogenous chromophore that canbe topically delivered to the hair follicles, therebymaking the removal of white, gray, red, and blondehair hypothetically possible. This concept wasfirst demonstrated with a topical carbon solutiondissolved in mineral oil (20). However, we havenoticed very little efficacy of topical chromophoresin our vast experience.

Informed consent

An explanation of the potential risks of LHRshould be reviewed as part of the informedconsent process. The risks include but are notlimited to temporary and permanent hypo/hyperpigmentation, blister formation, scar forma-tion, ulceration, hive-like response, bruising,infection, acne flare, and folliculitis. For thosepatients with Fitzpatrick skin type IV or greater orof Mediterranean, Middle Eastern, Asian or SouthAsian descent, the low risk of paradoxical hyper-trichosis (conversion of vellus hairs to terminalhairs), especially when treating the lateral faceand jaw, should be reviewed (21–24). Patientsshould be counseled that permanent and com-plete hair removal is not likely but that with mul-tiple treatments, significant long-term reductioncan be achieved. Hirsute women with hormonalabnormalities may require continued mainte-nance therapy and should be advised of this pos-sibility. Procedural pain is expected with LHRbut can be minimized with topical anesthetics.Erythema and edema are also expected withtreatment and may last up to 1 week. Patientsshould be aware of the need for strict sun avoid-ance for a minimum of 6 weeks before and aftereach treatment.

Preoperative preparation and laser safety

The need for topical anesthesia is variable amongpatients and particular anatomic sites. Varioustopical anesthetics including lidocaine, lidocaine/prilocaine, and other amide/ester anesthetic com-binations can be used to diminish the proceduraldiscomfort, and should be applied 30 minutes to1 hour before treatment under occlusion. Careshould be taken when using lidocaine or prilocaineto apply these medications to a limited area todiminish the risk of lidocaine toxicity or methemo-globulinemia, respectively.

Patients should be placed in a room with atreatment chair that makes the desired treatmentarea easily accessible. The room should beadequately cooled to keep the laser device fromoverheating and be free of any hanging mirrors oruncovered windows. A fire extinguisher should bereadily available, especially if oxygen is beingused. Having a vacuum device on hand duringtreatment can minimize the plume and unpleas-ant odor created by each laser pulse. Because theretina contains melanin which can be damagedby all LHR devices, proper eye protection is abso-lutely critical for both the patient and lasersurgeon. Each device requires the use of protec-tive goggles that are unique to the device’s par-ticular wavelengths. Goggles can not beinterchangeably used with laser or IPL devices ofother wavelengths. Furthermore, because of therisk of retinal damage, it is the authors’ strongopinion that one should never treat a patient forLHR within the bony orbit.

Device variables

Wavelength. The chromophore for laser hairremoval is melanin. Within the hair follicle,melanin is principally located within the hair shaft,although the outer root sheath and matrix area alsocontain melanin. Melanin is capable of functioningas a chromophore for wavelengths in the red andnear-infrared portion of the electromagnetic spec-trum (14), and can be targeted by ruby, alexandrite,diode, and Nd : Yag lasers, as well as IPL devices.

The long-pulsed ruby laser (694 nm) was thefirst device used to selectively target hair follicles(5), and result in long-term (follow-up at 2 years)hair loss (6 mm spot size, 270 ms pulse durationand fluences 30–60 J/cm2) (4). The long-pulsedruby laser can be safely used in Fitzpatrick skinphototypes I–III. A large multicenter trial of nearly200 patients showed that the majority of patientshad >75% hair loss on 6-month follow-up after an

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average of four treatments (25). At the time of press,there are no long-pulsed ruby lasers that are com-mercially available in the United States (Table 1).

The long-pulsed alexandrite (755 nm) laser hasbeen shown to be effective for hair removal in mul-tiple studies (26). The long-pulsed alexandrite lasercan be safely used in Fitzpatrick skin phototypesI–IV; although some experts limit the use of thelong-pulsed alexandrite laser to Fitzpatrick skinphototypes I–III. A few studies have demonstratedthe safety of the long-pulsed alexandrite laser ina large cohort of patients with Fitzpatrick skinphototypes IV–VI (27,28). A recent randomized,investigator-blinded clinical trial of subjects withFitzpatrick skin phototypes III–IV treated with along-pulsed alexandrite laser (12 and 18 mm spotsize, 1.5 ms pulse duration and fluences of 20 or40 J/cm2) for four sessions at 8-week intervalsshowed 76–84% hair reduction 18 months after thelast treatment (29) provides the best evidence forlong-term hair removal efficacy with the alexan-drite laser. A randomized controlled trial of 144Asian subjects with Fitzpatrick skin types III–V witha long-pulsed alexandrite laser (12.5 mm spot size,pulse duration of 40 ms, fluences of 16–24 J/cm2)found that subjects with three treatments had a55% hair reduction compared with subjects treatedtwice with a 44% hair reduction and subjectstreated once had a 32% hair reduction at 9 monthsfollow-up (30). Combination treatment of alexan-drite and Nd : Yag lasers provide no added benefitover the alexandrite laser alone (31). The commer-cially available long-pulsed alexandrite devices aresummarized in Table 1.

The long-pulsed diode (800–810 nm) laser hasalso been extensively used for LHR (26,32). Thediode laser can be safely used in patients with Fitz-patrick skin phototypes I–V. Two long-term non-randomized controlled studies showing roughly40% hair reduction at a mean follow-up of 20months after one or two treatments (9-mm spotsize, pulse duration of 5–30 ms, fluences of 15–40 J/cm2) (33), and 84% hair reduction at 1-yearfollow-up after four treatments (9-mm spot size,pulse duration of 5–30 ms, fluences of 12–40 J/cm2)(34) demonstrate the efficacy of the diode laserfor long-term hair removal.

The long-pulsed Nd : Yag laser has been thoughtto offer the best combination of safety and efficacyfor Fitzpatrick skin phototype VI patients. To ourknowledge, the evidence for long-term hair reduc-tion with the Nd : Yag laser is not as convincing asother LHR devices, although a nonrandomizedtrial reported a 70–90% reduction of facial, axillary,and leg hair growth 1 year after three monthly

treatments with an Nd : Yag laser (5-mm spot size,pulse duration of 50 ms, fluences of 40–50 J/cm2)(35). A small study of axillary LHR comparing long-pulsed alexandrite, diode, and Nd : Yag lasersshowed that both the alexandrite and diode laserswere significantly more efficacious than theNd : Yag laser for LHR (36).

IPL is composed of polychromatic, noncoherentlight ranging from 400 to 1200 nm. Various filterscan be used to target particular chromophores,including melanin. Long-term (>1 year) hairremoval has not been convincingly demonstratedto date. Various reports have demonstrated someshort-term efficacy (37,38). One study of patientstreated with a single IPL session reported 75% hairremoval one year after treatment (39). Two studiesproviding a head to head comparison of IPL versuseither the long-pulsed alexandrite laser (40), orNd : Yag laser(41) both found the IPL to be inferiorto laser devices for hair removal.

Fluence. Fluence is defined as the amount ofenergy delivered per unit area and is expressed asJ/cm2. Higher fluences have been correlated withgreater permanent hair removal; (5,42) however,they are also more likely to cause untoward sideeffects. Recommended treatment fluences areoften provided with each individual laser devicefor non-experienced operators. However, a moreappropriate method of determining the optimaltreatment fluence for a given patient is to evaluatefor the desired clinical endpoint of perifollicularerythema and edema (FIG. 2). The highest possibletolerated fluence which yields this endpoint,

FIG. 2. Appropriate clinical endpoint of perifollicularerythema and edema.

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without any adverse effects, is often the bestfluence for treatment.

Pulse duration. Pulse duration is defined as theduration in seconds of laser exposure. The theoryof selective photothermolysis(3) enables the lasersurgeon to select an optimal pulse duration basedon the thermal relaxation time (TRT). Terminalhairs are roughly 300 mm in diameter, and thus thecalculated TRT of a terminal hair follicle is roughly100 ms. However, unlike many other laser applica-tions, the hair follicle is distinct in that there is aspatial separation of the chromophore (melanin)within the hair shaft and the biological “target”stem cells in the bulge and bulb areas of the follicle.The expanded theory of selective photothermoly-sis(15) takes this spatial separation into accountand proposes a thermal damage time, which isthought to be longer than the TRT. Shorter pulsewidths are also capable of removing hair, but areprobably not as effective in producing permanenthair removal. Longer pulse widths are likely moreselective for melanin within the hair follicle andcan minimize epidermal damage as the pulsewidths are greater than the TRT of the melano-somes and melanocytes within the epidermis.

Spot size. The spot size is the diameter in millime-ters of the laser beam. Larger spot sizes are prefer-able to smaller spot sizes. As photons within a laserbeam penetrate the dermis, they are scattered bycollagen fibers, and those that are scattered outsidethe area of the laser beam are essentially wasted.Photons are more likely to be scattered outside ofthe beam area for smaller spot sizes, whereas in alarger spot size, the photons are likely to remainwithin the beam area following scatter (S. Kilmerand R. Anderson, unpublished data). Using thelargest possible spot size also minimizes thenumber of pulses it takes to cover a treatment area,thereby translating to faster treatment courses. Adouble-blind, randomized control trial of a long-pulsed alexandrite device for LHR of the axillaryregion comparing 18- and a 12-mm spot sizes atotherwise identical treatment parameters showeda 10% greater reduction in hair counts with thelarger spot size (43).

Skin cooling. The presence of epidermal melanin,particularly in darker skin types, presents a compet-ing chromophore to hair follicle melanin, which canbe damaged during LHR. Cooling of the skin surfacecan be used to minimize epidermal damage, whilepermitting treatment with higher fluences (44). Allof the skin cooling methods function by acting as a

heat sink and removing heat from the skin surface.The least effective type of cooling is the use of anaqueous cold gel which passively extracts heatsfrom the skin and then is not capable of further skincooling. Alternatively, cooling with forced chilledair can provide cooling to the skin before, during,and after a laser pulse. However, today, most of thecommercially LHR devices have a built-in skincooling system, which either consists of contactcooling or dynamic cooling with a cryogen spray.Contact cooling, usually with a sapphire tip, pro-vides skin cooling just before and during a laserpulse. It is most useful for treatments with longerpulse durations (>10 ms) (45). Dynamic coolingwith cryogen liquid spray (46) precools the skin witha millisecond spray of cryogen just before the laserpulse. A second spray can be delivered just after thelaser pulse for post-cooling, but parallel coolingduring the laser pulse is not possible as the cryogenspray interferes with the laser beam. Dynamiccooling is best suited for use with pulse durationsshorter than 5 ms.

Post-procedure care

It is expected for the patient to have perifollicularerythema and edema in the treatment area follow-ing LHR. This generally persists for 2 days but canlast for up to 1 week. Ice and application of a topicalcorticosteroid can be used to shorten the durationof these desired clinical findings. Patients will oftenfind that a single treatment of LHR with shorterpulse durations results in nearly total epilation ofthe hair follicles in the treatment area. It is impor-tant to counsel the patient that a majority of thesehairs will likely regrow, and this isn’t considered atreatment failure. Generally, only about 15% ofhairs are permanently removed with each lasertreatment. On the other hand, LHR treatments withlonger pulse durations may leave behind manyhairs which appear to “grow” following treatment.It is important to reassure the patient that these“growing” hairs are dislodged from the hair follicleand require 1–2 weeks to be completely shed.Nearly any method of epilation can be used tohasten their removal.

The importance of strict sun precaution follow-ing LHR treatments can not be overemphasized.This can be achieved by the use of topical sun-screens, ultraviolet light impermeable garments,and sun avoidance.

Complications

The most common complication of LHR is pig-mentary alteration, including hyper- and hypo-

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pigmentation (FIGS 3 and 4). This may resulteither from selecting a non-optimal wavelength,pulse duration, fluence, nonfunctional epidermalcooling, or by treating a tanned patient. Pigmen-tary alterations may also occur even when optimaltreatment parameters are used. These changes areoften transient and improve with time, althoughpermanent hypopigmentation can occur (FIG. 4).Zones of untreated hairs can result from a lack ofoverlapping between laser pulses (FIG. 5). Scarringis an exceedingly rare complication but can occurwhen excessive fluences are used.

Treatment of vellus hairs, especially of the lateralcheeks and chin area, may result in the inductionof terminal hairs, a phenomenon known as para-doxical hypertrichosis (FIG. 6). This has beenreported to occur more commonly in females ofMediterranean, Middle Eastern, Asian, and SouthAsian descent (21–24).

Conclusion

Future directions

Advances in pain control. A novel technique toreduce laser hair removal-associated pain is pneu-matic skin flattening (PSF) (47). PSF works by cou-pling a vacuum chamber to generate negativepressure and flatten the skin against the handpiecetreatment window. Based on the gate theory ofpain transmission, it stimulates pressure receptorsin the skin immediately prior to firing of the laserpulse, thereby blocking activation of pain fibers.PSF is just beginning to be incorporated into com-mercially available lasers (Table 1).

Home use laser and light source devices for hairremoval. In recent years, a number of devices havebeen developed that seek to provide patients with

A

C D

B

FIG. 3. (A, B, C, and D) Examples of laser hair removal-induced hyperpigmentation.

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the ability to achieve hair removal at home. Thesedevices are based on IPL, laser and thermal tech-nologies that target the hair follicle for destruction.These devices include Spa Touch (Radiancy,Orangeburg, NY, USA), Tria (SpectraGenics,Dublin, CA, USA), and no!no! (Radiancy).

The evidence behind such devices is scant andlimited to small noncontrolled studies (48–50). Inaddition, the risk for devastating eye injuries withimproper use of laser- and IPL-based devices andlack of medical training raises a dilemma of howmuch autonomy a patient should have with poten-tially harmful devices. Nonetheless, the appeal ofhaving a personal device to remove unwanted hairin the privacy of one’s home without the expenseand inconvenience of multiple dermatologist orspa visits will likely drive the development of addi-tional home-use devices.

Alternative technologies for hair removal. Photo-dynamic therapy with aminolevulinic acid hasbeen shown in a small pilot study to result in up to40% hair loss with a single treatment, although waxepilation was performed prior to treatment in thisstudy (51).

Electro-Optical Synergy (ELOS) technologycombines electrical (conducted radiofrequency(RF)) and optical (laser/light) energies (52). Ahandful of devices based on this technology have

A B

C D

FIG. 4. Permanent hypopigmentation resulting from laser hair removal. (A) Temporary hyperpigmentation in a Fitzpatrick skinphototype IV treated with an intense pulsed light device for hair removal. (B) One month later, the hyperpigmented patches werereplaced with persisting hypopigmented patches. (C) Temporary hyperpigmentation in a Fitzpatrick skin phototype VI patienttreated with an Nd : Yag device. (D) Two weeks later, the annular hyperpigmented patches were replaced with persisting hypop-igmented patches.

FIG. 5. Zones of untreated skin resulting from poor operatortechnique.

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been produced (Table 1). The theory behind ELOSis based on the optical component (laser or IPL)heating the hair shaft, which then is thought toconcentrate the bipolar RF energy to the surround-ing hair follicle. Based on this combination, lowerfluences are needed for the optical component,thereby suggesting it might be well tolerated in allFitzpatrick skin phototypes, and potentially effec-tive in the removal of white and poorly pigmentedhair. A study of 40 patients (Fitzpatrick skin pheno-types II–V) with varied facial and nonfacial haircolors were treated with combined IPL/RF ELOStechnology. An average clearance of 75% wasobserved at 18 months following four treatments.No significant adverse sequelae were noted andthere was no treatment differences betweenpatients of varying skin types or hair color (53).Pre-treatment with aminolevulinic acid prior touse of a combined IPL and RF device has beenshown to further augment the removal of terminalwhite hairs (54).

In conclusion, hair removal has made a dramaticshift from an art to a science based on the theory ofselective photothermolysis. Since the first reportsof selective hair removal in 1996 by Anderson andcolleagues (5), there has been a tremendous explo-sion in the number of devices used for LHR andmaking LHR the most commonly requested cos-metic procedure in the world. This review providesthe reader with the fundamentals of hair follicleanatomy and physiology, pearls for patient selec-tion and preoperative preparation, principles oflaser safety, an introduction to the various laser/light devices, and a discussion of laser–tissue inter-actions that are vital to optimizing treatmentefficacy while minimizing complications and sideeffects.

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