Plastic Surgery for Laser Hair Removal

Laser hair removal is one method of treatment for unwanted body hair. Up to 22% of women in North America have excessive or unwanted facial hair, which negatively affects the quality of life for many individuals.[1] Men also feel compelled to rid themselves of unwanted body hair, as dictated by popular culture and appearance anxieties. Body hair may be undesirable to patients for cultural, social, cosmetic, or psychological reasons; unwanted hair can result in feelings of embarrassment or emotional burden that may impede patients' relationships or daily activities. This level of impairment is comparable to that experienced by patients with psoriasis and eczema and eclipses that experienced by patients with acne.[2]

Adequate methods for hair removal have long been in demand; long-term hair removal with minimal adverse effects is the ultimate goal. Laser hair removal has become well established as an effective form of treatment for unwanted body hair.

An estimated 757,808 laser hair removal procedures were performed in the United States in 2020, according to the American Society of Plastic Surgeons, with 84% performed in females.[3]  None of the hair removal methods practiced today provides complete or permanent hair removal. This goal will likely be reached with a more complete understanding of anatomy, physiology, hair growth cycles, and laser-tissue interactions, and as more sophisticated technologies emerge.

For news, CME, and expert viewpoints on aesthetic procedures, visit Medscape’s Aesthetic Medicine Resource Center.

Numerous methods are successful in temporarily removing hair.[1, 4]

• Manual plucking

  • This method is an easy and practical way to remove single hairs and can be utilized by most individuals for clearing small numbers of unwanted hairs. The hair shaft must be long enough to be grasped by tweezers.

  • Plucking often induces a hair follicle into its active growth phase, or anagen, thus stimulating new hair growth. Additionally, it can create postinflammatory hyperpigmentation, true or pseudofolliculitis, and, very rarely, scarring.

• Shaving

  • Although fast and effective for clearing a large surface area of hair, shaving is the most temporary method of hair removal, as it only cuts the hair at the skin surface. As the hair continues to grow, the blunt end of the cut hair is more noticeable because it is thicker than a normal tapered end.

  • Disadvantages include skin lacerations, potential pyoderma, folliculitis, ingrown hairs, and postinflammatory hyperpigmentation. Many women may not use this method on certain areas of the body because of masculine connotations of shaving the face and neck.

• Waxing or sugaring[5]

  • Application of a warmed wax or a sugary paste to areas of hair-bearing skin and then removing it, along with the unwanted hair, is a popular method of hair removal and is commonly performed at salons and spas. This method may be used over large skin surface areas (eg, legs, arms, back) or small controlled areas (eg, face, eyebrow, bikini area). New hair growth appears more slowly than with shaving, as the hair must grow to the level of the skin surface before it appears.

  • Stripping of the wax or sugar paste from the skin is often unpleasant or painful and may cause adverse effects such as irritant dermatitis, true or pseudofolliculitis, hyperpigmentation, scarring, and thermal burns from hot wax or poor technique.

• Depilatory preparations

  • Preparations containing thioglycolates or strontium sulfide are the most widely used chemical depilatories. These agents disrupt the disulfide bonds (especially cysteine) that hold hair cells together, thus dissolving the hair. Like shaving, this method offers only a brief hair-free period, as hair continues to grow from the level of the skin surface.

  • The major adverse effect is the potential for irritant or allergic contact dermatitis, which may cause significant itching or rash.

• Chemical bleaching

  • Bleaching with hydrogen peroxide is an effective method of disguising the presence of hair but does not actually remove hair.

  • This is particularly effective for individuals with fine but dark and, therefore, noticeable hair on the arms, face, or neck.

• Electrolytic therapy

  • Successful electrolysis can achieve permanent hair follicle destruction to some degree in 15-80% of patients. Galvanic electrolysis employs a weak direct current that passes through a negative electrode (anode) inserted in the hair follicle and a positive electrode (cathode) in the form of a wet pad in the patient's hand. Follicular destruction is achieved via the formation of toxic sodium hydroxide (a free radical). Electrothermolysis uses an alternating current that causes direct thermal destruction of the hair follicle. A combination or blend technique of both galvanic electrolysis and electrothermolysis may be used, which is considered by many users to be more effective, more rapidly performed, and with less discomfort.[6]

  • Each hair must be treated individually and the process is slow and may be painful. Adverse effects include pain, scarring and hypo- or hyperpigmentation.

• Medicated treatment with eflornithine

  • Available by prescription only, eflornithine 13.9% cream was approved for topical use by the Food and Drug Administration (FDA) on July 31, 2000. Topical eflornithine may irreversibly inhibit skin ornithine decarboxylase activity, resulting in a reduction in the rate of hair growth.[1] The onset of action may take 4-8 weeks of using the topical cream for unwanted facial hair on the mustache and chin area.

  • The most common adverse effects of topical eflornithine cream include, but are not limited to, acne, pseudofolliculitis barbae, skin irritation, and rash.

• Laser hair removal

  • Since 1996, when photoepilation-using laser technology first became available for use, numerous advances have occurred in laser hair removal, resulting in different types of lasers now available for treatment of excessive hair. Laser hair removal is based on the theory of selective photothermolysis, or selective destruction of the follicular unit, resulting in significant hair reduction in treated areas.

  • Adverse effects are primarily related to epidermal damage by partial absorption of laser energy by the surrounding skin. This effect has been more pronounced in darker-skinned individuals whose increased skin melanin concentration places them at a higher risk of adverse effects. These adverse effects include blistering, hypo- or hyperpigmentation (see image below), scabbing, or, very rarely, permanent scarring.

    Hyperpigmentation and hypopigmentation following use of inappropriate parameters on a patient with Fitzpatrick phototype IV.

Excessive hair growth in men or women may be classified into either hirsutism or hypertrichosis, depending upon the distribution on the body. Other disorders, such as pseudofolliculitis barbae or acne keloidalis nuchae, may be caused by the hair itself, causing ingrown hairs and localized inflammatory reactions that may result in pigmentary disorders, hair loss, and scarring.

Hirsutism

Hirsutism is defined as an excess of thicker darker hairs in a male pattern of distribution where they are normally thin or absent in the female.[7] Affected areas are those that are stimulated by circulating androgens and include the face, chest, arms, and areolae. This disorder may be caused by several types of endocrine disorders that lead to excessively high androgen levels or by hair follicles that are particularly sensitive to normal levels of androgens. The latter accounts for approximately 95% of all reported cases. An estimated 1 in 20 women of reproductive age are affected by this disorder.

Treatment for excessive hair in hirsutism is not generally required if no clear etiology of the disorder exists and the patient does not find the excessive hair growth objectionable. However, treatment generally relies upon antiandrogen to inhibit the effects of androgens on the skin, such as 5-alpha-reductase inhibitors, spironolactone, or flutamide.[8] Whether choosing to treat medically or with any of the aforementioned methods of hair removal, patients must understand that treatment is long-term and must be continued to maintain low levels of visible hair.

Hypertrichosis

A hair growth pattern in a nonandrogen-dependent pattern is termed hypertrichosis and may involve vellus, terminal, or lanugo type hair. This may be associated with a number of congenital syndromes or occur as an isolated finding. What is considered a normal amount and appearance of body hair can vary widely among different ethnic groups, and treatment should be tailored to the needs or desires of the individual patient. Hypertrichosis may be an unwanted adverse effect of medications such as cyclosporine, minoxidil, and oral and topical corticosteroids that are used to treat other disorders.

Pseudofolliculitis barbae

When hair grows in a curly and tightly coiled pattern, patients may be afflicted with numerous ingrown hairs that may cause skin irritation, papules, and pustules. These may eventually lead to changes in pigmentation and even scarring. Pseudofolliculitis barbae occurs most commonly in the underarm or bikini area with shaving, or, in men, at the lower neck, where coarse facial hair grows. Laser hair removal is effective in treating this disorder by temporarily or permanently removing the hair from the chronically inflamed lesion. Laser treatment leads to resolution and healing of the papular and pustular lesions, dramatically improving skin texture and the associated postinflammatory hyperpigmentation.

Acne keloidalis nuchae

Acne keloidalis nuchae is most commonly seen in African Americans and is characterized by follicular papules and chronic plaques on the occipital area of the scalp. It may often lead to keloidal thickening of the skin and permanent scarring. In early lesions, an entrapped hair is usually in evidence, and early treatment with laser hair removal is most effective at this stage. The entrapped hair acts as a foreign body in the skin and, when chronic, can cause skin changes, decreased hair growth, and scarring of the affected area. The treatment goals with laser hair removal for this disorder are to destroy the impacted hair and cause a delay in new hair growth, thus decreasing further scarring.[9]

In order to gain a more comprehensive understanding of how laser hair removal procedures work, one must have knowledge of relevant hair microanatomy, physiology, and growth cycles associated with growth of hair on the body.

Hair follicles are found over almost the entire body surface, with the exceptions of the palms of the hands and soles of the feet. Each person has approximately 5 million individual hair follicles. Hair follicles may be straight, wavy, helical, or spiral, and the morphologic features of follicles vary among different anatomic locations and racial backgrounds. White persons typically have thinner hair shafts than persons of Asian or African American backgrounds. The density of hair follicles in a given skin surface area also varies widely among individuals. Hair shape is also highly variable; on cross-section, straight hair tends to be round and wavy or spiral hair is oval. Keep in mind the variations in color, texture, and amount of hair on a given body surface area when deciding upon the need for hair removal procedures.

Types of hair

Adult hair has 2 primary types. Vellus hair can be found over the entire body and appears as soft, fine, short hairs that are nonpigmented or very lightly pigmented and can be all but invisible. Terminal hair is the longer, coarser, and more darkly pigmented hair found on the scalp, underarm area, and groin. Subgroups of terminal hair include those on the scalp, pubic region, and eyebrows. Terminal hair is also found on the androgen-sensitive areas of the body, such as the beard and chest area in males. Although greatly outnumbered by vellus hairs, terminal hairs are more important, as they are responsible for the appearance of hair on the body. They may aid in enhancing a person's image, or they can cause great anguish and distress due to their distribution, length, or texture.

Hair follicle anatomy

Hair follicles are associated with other structures within the skin. As the hair follicles develop, they become associated with developing sebaceous glands, apocrine glands, and erector pili muscles. Together, these structures form the folliculosebaceous-apocrine unit.

Each hair follicle may be divided into 4 histologic divisions, which are (from superficial to deep) the infundibulum, isthmus, stem, and bulb.

• The infundibulum is the most distal portion of the hair in the follicle, extending from the surface of the skin down to the entrance of the apocrine gland into the follicle.

• The isthmus of the hair then extends from the apocrine gland entrance to the connection to the sebaceous gland.

• Still deeper, the stem extends from the sebaceous gland opening to the erector pili muscle attachment. The action of this muscle makes the hair stand erect, causing goose bumps.

• The bulb of the hair follicle is deep to the attachment of the erector pili muscle and is the site of the follicular matrix. This is the principal site responsible for hair growth and development.

Hair phases

Adult hair has 3 distinct phases of development: anagen, catagen, and telogen. As hairs progress through these phases, they are affected differently by treatment with laser-assisted hair removal.

• Anagen is the phase in which active hair growth occurs. Follicular matrix cells are actively producing cells that will make up the growing hair. The growing hair consists of all 4 histologic divisions in anagen.

• In catagen (the regression phase), matrix cells degenerate and the bulb begins to atrophy, causing the hair follicle to shrink.

• Telogen is the final resting phase of the hair follicle. Growth of the hair has stopped, and the follicle becomes inactive. Now the follicle contains only the superficial components, the infundibulum and the isthmus. During telogen, the hair is released from its attachment to the skin and sloughs away. The process begins again in anagen to form a new hair.

The length of time spent in each phase depends upon the location of the hair. On the scalp, hair follicles spend up to 10 years in anagen, but on the trunk, brow, and limbs, anagen lasts no longer than 6 months. Catagen lasts only 2-3 weeks, and telogen lasts from 3-4 months.

Up to 90% of hairs in a given body location can be in the anagen phase at a given time. This fact becomes important because only hairs in the anagen phase of development are susceptible to injury during a session of laser-assisted hair removal. Thus, multiple treatments are necessary to treat all hair follicles on a given body surface area.

Melanin

Melanin is a biologic pigment that is found in many cells in the body and is primarily responsible for the color of the skin and hair. The primary function of melanin in the skin is to protect it from the harmful effects of sunlight. The amount of melanin in hair and skin varies widely between individuals and races and is determined by the concentration of melanin within the skin. This variability produces a great range of hair darkness, skin color, and tone.

Melanin is the target chromophore, or light-absorbing molecule, for laser treatment and has an absorption spectrum of 250–1200 nm, which spans the entire ultraviolet, visible, and infrared light ranges. Melanin absorbs energy in the form of heat from a pulse of laser light. This heat causes thermal injury to the melanin-containing cell and its surroundings. Ideally, the laser energy is absorbed selectively by the melanocytic hair bulb and matrix, thus destroying the hair follicle and its capacity to regrow, while protecting the surrounding tissue where the melanin concentration is minimal. In persons with darker skin, however, the higher levels of melanin in heavily pigmented skin compete as a chromophore for the laser light. This light is converted to heat and can cause skin blistering or changes in skin pigmentation.

See the list below:

• Patients with hirsutism may actually have a more serious underlying endocrine disorder. Causes of hirsutism should be avidly sought and treated, if necessary.

• For patients with chronic or active herpes simplex virus infections, pretreatment with antiviral medications can be initiated, especially when lesions appear in the body area to be treated. Antiviral treatment typically begins 1 day prior to laser treatment and continues for a total of 5-7 days.

• Patients with a history of hypertrophic scarring or keloid formation should be treated judiciously because of possible problems in healing if skin damage is sustained.

• Patients taking isotretinoin (Accutane) should stop the medication for 6 months prior to laser hair removal treatment because of skin sensitivity. This issue has been addressed but has not yet been proven in a clinical trial.

• Laser hair removal may be contraindicated in patients taking photosensitizing drugs activated by ultraviolet A wavelengths. Lasers operating in the visible to infrared spectrum are generally thought to be safe for use with patients taking these medications.

• Patients with tattoos on the body surface areas selected for laser hair removal should be instructed that the appearance of the tattoo might be affected by the use of laser devices. Treatment may lighten or darken certain pigments of the tattoo.

• Effective hair removal with laser-assisted devices requires the presence of a hair follicle for photothermolysis to commence. Prior history of recent waxing, plucking, sugaring, electrolysis, or other methods of complete hair removal should be ascertained.

Laser-assisted hair removal is accomplished by destroying the follicular unit and thus inhibiting future hair growth by the follicle. The ability to accomplish this without damaging any surrounding tissue is based on the theory of selective photothermolysis. The theory states that at a particular wavelength (in nm), pulse duration, and fluence matrix, lasers or other light sources with wavelengths within the absorption spectrum of melanin are effective for hair removal. Typically the pulse duration, or length of time the pulse of light is emitted, should be shorter than or equal to the thermal relaxation time (TRT) of the target. The TRT of a hair follicle is from 10-100 milliseconds. However, pulses longer than the TRT of the hair shaft allows thermal damage to occur in the hair matrix stem cells and ensure follicular destruction. In order to minimize the risk of thermal damage to surrounding skin cells, cooling devices may be used to chill the skin before or during laser treatment.

Since the first lasers were approved for the use of hair removal in 1996, dramatic advances have occurred in laser technology. This has led to the development of several laser types for the treatment of unwanted hair. Before the widespread use of longer wavelengths and pulse durations and more effective cooling devices, laser-assisted hair removal was best used to treat individuals with light skin and dark hair. More recently, however, long-pulsed lasers have been used to safely and effectively treat patients with darker skin types. Laser light sources currently used to destroy hair photothermally include the long-pulsed ruby (694 nm), long-pulsed alexandrite (755 nm), long-pulsed diode (810 nm), and long-pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG, 1064 nm). The efficacy of these different lasers for treatment of unwanted hair and the frequency of adverse effects encountered after treatment have been compared in various skin types.[10, 11]

The efficacy of each of the following laser systems is compared in terms of permanent hair reduction. Hair reduction, as defined by the FDA, "refers to a significant reduction in the number of terminal hairs after a given treatment, which is stable for a period of time longer than the complete growth cycle of hair follicles at the given body site."

Long-pulsed ruby

The long-pulsed ruby laser was the first widely used laser for hair removal. Its light energy has the most selective absorption by melanin and the shortest depth of penetration (wavelength of 694 nm). Use of this laser for hair removal is indicated in individuals with light skin and dark hair. Its efficacy in individuals with light skin has been demonstrated in numerous studies, ranging from 20-60% hair reduction after one treatment and up to 50-78% reduction after multiple treatments. The ruby laser penetrates the skin by only 1-2 millimeters and can cause significant absorption by epidermal melanin of thermal energy. In studies treating a wide range of skin types with the ruby laser, more adverse reactions have occurred in patients with darker skin. The use of this laser on patients with darker skin types is not recommended.

Long-pulsed alexandrite

The 755-nm alexandrite laser has now been widely used for laser hair removal and is recognized as being efficacious and generally safe. This laser is still typically used for patients with lighter skin types, but its longer wavelength allows for deeper penetration into the skin, and it can be used for patients with darker skin.[10] Studies have reported hair reduction from 4-56% after only a single treatment and from 33-95% hair reduction after multiple treatments, depending upon number of treatments and body location. The adverse effects of this laser, when used on patients with darker skin types, can include blistering, crusting, and alterations of pigment, even when skin cooling devices are used. In patients classified as having the darkest skin, residual hypo- or hyperpigmentation is the rule with the alexandrite laser.

Long-pulsed diode

Treatment of unwanted hair with the 810-nm long-pulsed diode laser has been demonstrated as comparable to those of the ruby or alexandrite lasers. After a single treatment, hair reductions of 32-34% have been reported, and up to 84% hair reduction has been reported after multiple treatments. The diode laser has a longer wavelength and adjustable pulse duration, and, when used with an efficient skin-cooling device, allows for the treatment of patients with darker skin types. The diode laser is more effective for laser-assisted hair removal in patients with dark skin because of the higher absorption by melanin than is seen with the Nd:YAG laser. Still, temporary adverse effects have been reported with the use of the diode laser in the form of postinflammatory hyperpigmentation when used on individuals with dark skin.[12]

Long-pulsed Nd:YAG

The Nd:YAG laser is the safest type used to treat unwanted hair on patients with dark skin and is most suitable for patients in this group. At 1064 nm, this laser penetrates the skin deeper than other lasers (to a level of 4-6 mm) with less absorption at the skin, but it is also less effectively absorbed by melanin. This leads to lower instances of adverse effects and better tolerance in patients with dark skin, but also lower efficacy for hair removal.[13] Permanent hair loss has been reported, however, with reported hair reductions of 27-53%, depending on the number of treatments administered and the body location.

The FDA has approved the long-pulsed diode and the long-pulsed Nd:YAG lasers for use in hair removal in patients with darker skin classifications. All FDA-approved laser systems used for hair removal must have efficient and effective epidermal cooling devices incorporated as part of the system.

Intense pulsed light systems

Pulsed, noncoherent broadband light sources are now accepted and widely used in the medical industry for hair removal and other applications. Intense pulsed light (IPL) systems utilize a xenon bulb as a light source, which produces polychromatic light with wavelengths from 550-1200 nm. This is in contrast to laser light sources, which produce monochromatic light of a specific wavelength. Light emitted by the bulb passes through a filter that excludes shorter wavelengths that may severely damage skin. The ability to "tune" the wavelength of light emitted by these systems gives IPL systems the advantage of versatility. Using different filters, a pulsed light system could mimic any number of laser systems, allowing the operator to treat many different conditions amenable to light therapy, including, of course, the removal of unwanted hair.

Studies have shown intense pulsed light to be an effective method of hair removal. In a study of 210 patients who underwent hair removal by IPL, a mean hair reduction of 80% was reported after 3-5 treatments. Minimal adverse effects, including transient erythema and localized edema, were reported.

The variability of light output can also be a disadvantage of IPL systems. The light spectrum may vary slightly with each pulse, and reproducibility of treatments varies between operators. The handpieces of IPL systems are typically larger than laser-based systems, which makes treatment of fine areas of the skin difficult.

A large discrepancy can exist between patient expectations of treatment with laser-assisted hair removal systems and the actual effects of such a treatment. Open communication must exist between the care provider and the patient. A body surface area does not realistically remain completely hair-free after a single laser-assisted hair removal treatment.

Expectations

See the list below:

• Approximately 80% of all patients respond well to laser hair removal therapy.

• Patients should be counseled to expect a 30% decrease in hair at the treatment area with each laser treatment.

• Patients should understand that multiple treatments are often necessary to achieve the desired reduction in hair at a given body area. A minimum of 5 treatments is often necessary to achieve optimal patient satisfaction.

• Treatments are typically spaced 1-3 months apart.

• Individual response to laser-assisted hair removal is highly variable and depends upon numerous factors, including skin color, hair color and size, laser type, fluence, wavelength, and skin preparation.

• Laser hair removal is not without risk. Some discomfort may be associated with the procedure. Patients must also understand the potential for adverse effects, adverse reactions, and complications of laser treatment for unwanted hair.

• The best candidate for laser hair removal is a patient with light skin and dark hair.

Skin preparation and safety

See the list below:

• Patients should be instructed to avoid sunlight and active tanning prior to treatment. Bleaching of the skin with retinoic acid or hydroquinone can lighten the skin prior to laser treatment.

• Patients may shave or use depilatory creams up to the day prior to treatment, leaving hairs within the follicle and below the skin surface.

• Topical anesthetic creams or cryogenic sprays may be applied to the treatment area to reduce discomfort during the procedure. Cold compresses are also effective in reducing discomfort, erythema, and edema at the treatment area.

• The skin surface must be thoroughly cleansed of all makeup, anesthetic creams, and other applicants immediately prior to laser treatment. This may be done with water, followed by alcohol swabs, and should be allowed to dry completely.

• Laser systems are dangerous hazards to the eye. The highest concentration of melanin in the body is contained in the retina, which is highly susceptible to damage by laser light. Every person in the room during laser treatment should wear protective eyewear that is certified for the wavelength of the laser in use. Because the patient usually lies supine, he or she may require full occlusive eye protection to prevent laser light from entering underneath a sunglasses or goggle type of protective eyewear.

Optimal outcomes of laser-assisted hair removal are obtained with the highest fluences, appropriate pulse duration, and the largest laser spot size. Test spots may be performed prior to treatment of larger areas to determine to highest fluence tolerated by the individual patient and the laser's effect on surrounding skin. The amount of fluence used should also depend upon the area of the body to be treated and the density of hairs at the site.

• In areas with thick, dense hairs, such as the beard area or upper back in men or the bikini area in women, a lower fluence should be used until the hair has sufficiently thinned. Epidermal damage could otherwise occur, due to the additive thermal energy absorbed by the higher density of hair follicles.

• When treating the brow area on men or women, the skin should be pulled up and away from the eyes and should overlay a flat portion of the forehead. This helps minimize the risk of laser light exposure to the eye and retina.

• A higher occurrence of adverse effects and adverse reactions has been noted at the neck region in women; higher fluences in this area should be used with caution.

• For treatment of the chin, perioral region, or upper lip, tooth enamel should be protected from excessive laser light exposure. Inappropriate exposure to certain laser light may induce hard tissue disintegration in the tooth and irreversible damage to dental pulp.

To minimize the possibility of thermal damage to skin and to improve patient comfort, the skin should be cooled during laser-assisted hair removal. As previously stated, all FDA-approved laser systems have an epidermal cooling device incorporated into the handpiece. Incorporated cooling mechanisms currently in use include cryogen sprays, sapphire-cooled hand pieces, and cold airflow.

• Cryogen sprays are used in short bursts prior to each pulse of laser light. Increasing the length of cryogen spurts can decrease the pain felt by the patient.

• A pre-cooled, heat-sinked sapphire window or water-cooled glass window can be incorporated into the laser handpiece. This comes into contact with the skin to be treated and cools the skin.

• Some laser handpieces contain a source of continuous cooled air. This cold air is blown over the area to be treated and cools the skin during laser treatment.

• Cold compresses or ice packs may be used prior to treatment, along with cooled laser handpieces. These may be applied prior to treatment or intermittently during a longer treatment time.

• Application of a cooled gel (eg, ultrasound, aloe vera) to the skin can aid in minimizing discomfort and epidermal damage. All gel must, however, be thoroughly removed from the skin prior to treatment.

A recent study has introduced a pneumatic skin flattening (PSF) device as an alternative to the dynamic cooling devices that are currently used.[14] This device generates negative pressure on a small area of the patient’s skin, elevating and flattening the skin onto a sapphire window in preparation for laser therapy. This feeling of pressure against the skin may block the sensation of pain experienced by the patient. Study results thus far show that this method of treatment can be successful.

A study by Nistico et al indicated that in patients undergoing hair removal with an Nd:YAG laser, the use of an “in-motion” technique with minimal-emission produces comparable hair-removal results as the standard procedure with a long-pulsed laser, while causing less pain. The in-motion procedure involved continuously moving the Nd:YAG handpiece “in a slow linear/circular motion, creating an area of 10 × 10 cm and executing multiple back-and-forth passes.” Hair reduction in the standard-treatment group was reported as 82.2%, and in the in-motion group as 79%, there being no statistical difference. The visual analogue scale score for pain in the standard-treatment group was 6.05, compared with 3.55 for the in-motion group, a statistically significant difference.[15]

During laser treatment, each laser spot should overlap by no more than one third of the spot size. Further overlapping of continuous pulses causes accumulation of thermal injury and potentially causes epidermal damage. No overlapping of spots could result in missed areas in the treatment area. A treatment grid could be applied to the patient's skin and used as a guideline to outline the treatment area. With experience, the laser operator becomes proficient in visually tracking the treatment area.

See the list below:

• Immediately after a treatment session, patients should be given a cold compress or ice pack to decrease pain and reduce swelling. This effectively reduces discomfort, edema, and erythema, and keeps epidermal adverse effects to a minimum.

• Patients may also be given a topical corticosteroid cream to decrease local erythema.

• If minor skin damage has occurred, a topical antibiotic ointment may be applied until the skin has sufficiently healed.

• For more serious skin damage, an oral antibiotic may be prescribed for prophylaxis if deemed necessary by the health care provider.

• Makeup may be applied to treated areas the day following the procedure, as long as no epidermal damage has occurred.

• Patients should be told that hair casts will shed from treated areas over the following week and that this should not be confused with new hair growth.

Future treatments should be planned when they are likely to be most effective. Timing depends upon the body surface area to be treated. Hair on the trunk and extremities grows more slowly than on the face and head, and future treatments to the trunk and extremity should be planned after 2-4 months. In women, facial hair is lighter in color and finer in texture than on other parts of the body. These hair properties make the face a resistant area to treatment. Therefore, greater numbers of treatments are often required, and at shorter intervals. Treatments of the face should be timed at intervals of approximately 4-6 weeks.

Immediate effects after a single treatment of laser-assisted hair removal include perifollicular erythema and edema (see image below). These are expected after treatment and should not be considered adverse effects. They are minimized by cold application and resolve in a few hours.

The risk of developing adverse effects or complications after laser-assisted hair removal varies widely and depends upon many factors. The type of laser used may contribute to the incidence of adverse effects.

• The highest incidence of adverse effects has been reported to occur in patients with darker skin who were treated with the long-pulsed ruby laser.

• For individuals with darker skin, the long-pulsed diode laser and the long-pulsed Nd:YAG laser are recommended, and the Nd:YAG laser has been shown to have the least incidence of adverse effects.[16]

The incidence of adverse effects was reported after laser-assisted hair removal was performed on 480 patients. Reported adverse effects included (from highest to lowest incidence) blistering, hyperpigmentation, scabbing, hypopigmentation, scar formation, and thrombophlebitis.

• Blistering appears to be the most common adverse reaction and has been reported after treatment with all of the laser systems in use today over various skin tones. Blistering is a result of injury to the epidermis, possibly due to high fluences or increased overlapping of laser pulses.

• Scab formation is also a common adverse effect of laser treatment, due to epidermal damage. Blistering and minimal epidermal crusting have been reported in up to 15% of patients treated with both ruby and alexandrite lasers. These occurrences are more common in patients with tanned skin and darker skin types.

• Hyperpigmentation is a darkening of the skin and can occur after laser treatment. This phenomenon is usually reversible and is due to a stimulation of melanin production in skin melanocytes. This reaction is similar to a suntan.

• Hypopigmentation, or lightening of the skin, can occur after laser treatments. This is caused by damage to the epidermal melanocytes after their melanin absorbs laser light energy, causing destruction of these cells. This type of damage may be permanent and occurs more commonly in patients with darker skin.

In a comprehensive evidence-based review of hair removal using laser light sources, outcomes from different laser treatments were evaluated. The levels of efficacy and adverse effects from treatment with ruby, alexandrite, diode, and Nd:YAG laser light sources were compared from the results of 8 randomized, controlled and 20 controlled trials.

• Substantial objective evidence exists for partial hair removal with efficacy up to 6 months from treatments with ruby, alexandrite, diode, and Nd:YAG laser systems. Efficacy improved with each laser system when repetitive treatments were administered.

• The efficacy of hair removal with each laser system is superior to other, more conventional treatments such as waxing, shaving, or electrolysis.

• Evidence of long-term hair removal efficacy (>6 mo) exists from 2-4 treatments with alexandrite and diode lasers and is most likely after treatment with ruby (3-4 treatments) or Nd:YAG (5 treatments) laser systems.

A prospective, double-blind, randomized study by Ormiga et al indicated that the diode laser and intense pulsed light (IPL) can both successfully remove axillary hair. However, the report, which involved 21 female patients, found the diode laser treatment to be more effective, albeit more painful, than IPL therapy.[17]

Active communication must exist between the clinician and the patient regarding indications, expectations, and treatment goals before laser-assisted hair removal treatment begins. The FDA definition of permanent hair reduction should be reviewed with the patient seeking treatment, as evidence-based clinical trials report their results based upon this definition. Advertisements throughout the media often portray laser-assisted hair removal that could lead to unrealistic goals of treatment, and this approach may lead to more realistic expectations from both the clinician and the patient.

New personal handheld thermal or laser devices are quickly becoming available for patients to use at home for the treatment of unwanted hair.[18, 19] Devices such as the no!no! (Thermicon, Radiancy Inc, Orangeburg, NY) is a thermal, handheld self-treatment device now available for retail purchase.[18] It uses a hot-wire, which is passed approximately a half millimeter above the skin where it contacts the hair follicle. The ability of this device to reduce long-term hair growth has not been established, and one small study comparing hair counts after treatment with the device showed no benefit over shaving through a 3-month period.[20]

Other laser based devices, such as the Tria (SpectraGenics Inc, Pleasanton, Calif) and the pulsed light–based Silk’n (Home Skinovations Ltd, Yokneam, Israel) will soon be available for home treatment as well. These devices should be used only after all risks and benefits are fully understood by the consumer. Consumers should discuss any questions with their healthcare providers before considering any type of self-treatment.