Laser hair removal is a procedure used to remove unwanted hair. It is faster and less painful than other methods of hair removal, as well as longer lasting and more permanent.

The procedure uses laser light energy, which passes through the skin to destroy hair follicles. Hair in the treated area may be permanently reduced and hair that does grow back tends to be slow-growing, as well as thinner and lighter. Multiple treatments are typically necessary, and people with light skin and dark hair tend to have the best results. Any area of hair can be treated, with the exception of the area around the eyes.

Laser hair removal is typically performed by a technician, who is supervised by a dermatologist. The patient’s skin type and hair are evaluated and a spot test is usually done to assess response. If the patient has a tan, the treatment must be postponed until the tan completely fades.

During the procedure, the patient may feel mild discomfort or pain. The treatment may take a few minutes to several hours, depending on the size of the area treated.

Redness and swelling will occur in the area following treatment and usually goes away in several days. The patient can return to normal activities immediately, but avoiding direct sun exposure is generally recommended for at least a week.

Adverse effects are rare if the procedure is performed properly by an experienced laser technician. The most common side effect is lightening or darkening of the skin. Other possible reactions include burning, blistering and scarring.

Laser hair removal is a relatively new method of removing unwanted hair. It is faster and less painful than electrolysis (uses electric current to damage hair follicles) but more expensive. Multiple treatments can permanently eliminate some hairs and delay the growth of others. It is particularly useful for treating excessive hair growth conditions (e.g., hirsutism, hypertrichosis) but may be used to eliminate nearly any unwanted hair.

Human hairs may be either terminal (darkly pigmented, coarse and long) or vellus (lightly pigmented, fine and short). Laser hair removal typically targets terminal hairs. Both forms share the same anatomy. The lowermost part of the hair follicle is the bulb. Located in the dermis, this bulb is responsible for the formation of the hair. Damage to the bulb may make it unable to produce hair, resulting in permanent hair loss.

Hair growth occurs in cycles, including an active growing cycle (anagen) and a dormant cycle in which the hair does not grow (telogen). It is only in the active growing cycle that the bulb can be damaged to make it incapable of producing hair.

Because hair growth cycles are staggered throughout the body (some hair is in anagen while some is in telogen), multiple laser treatments are necessary to produce maximum permanent hair reduction.

During laser hair removal, laser light energy passes through the skin and targets the pigment melanin in the hair follicles. Melanin absorbs the energy and the hair follicle is heated and destroyed without harming the skin and surrounding tissue. This temporarily halts hair growth and permanently reduces, thins and lightens hair in the treatment area.

Some individuals experience long-term hair removal which lasts for several years. Others will require regular treatments every one to three months to maintain the hair loss. The degree of permanent hair reduction depends on several factors, including the color and coarseness of the patient's hair, and the fluence (density of light) used. Multiple treatments (usually around four) are necessary for maximum hair reduction and may be staggered by weeks or months. The highest tolerated fluence is required for optimal results and treatment responses vary among individuals. It is impossible to predict the number of treatments a peson will require or the length of time their hair will remain absent.

Generally, patients with light skin and dark hair have the best results. The treatment is more effective on light skin because there is less melanin in the skin to compete for laser energy, so the energy more effectively targets the hair follicle instead of the skin. Patients with dark skin tend to experience more side effects because of the higher levels of melanin in the skin. There are newer methods of laser treatment that can be used for patients with dark skin (e.g., Nd:YAG lasers).

Conversely, the darker the hair, the more energy is absorbed and the more effective the treatment. Individuals with light hair (e.g., blonde, red) do not respond to laser hair removal because their hair follicles lack the pigment needed for the hair to absorb the laser's energy.

Laser hair removal can be used in any area other than around the eyes. Commonly treated areas include the upper lip, chin, ears, chest, back, armpits, legs and arms. Areas of thin skin (e.g., armpits, bikini area) tend to respond better than areas of thick skin (e.g., back, chin), requiring fewer treatments.

Numerous lasers and light sources are currently available for use in laser hair removal. Different lasers may be better suited for different skin types and hair color. Lasers and light sources used in hair removal include:

• Ruby. Uses a wavelength of 694 nanometers (nm) and a pulse duration of 1.2 to 3 milliseconds (ms). Aqueous gel, cool contact glass or sapphire cooling systems are used to cool the skin before delivery of laser pulses.
  
  
• Alexandrite. A wavelength of 755 nm and a pulse duration of 2 to 40 ms is used. Aqueous gel, cold air flow or dynamic (cryogen spray) cooling systems are employed.
  
  
• Diode. A wavelength of 800 nm is used with a pulse duration of 5 to 30 ms and a sapphire cooling system.
  
  
• Nd:YAG (neodymium:yttrium-aluminum-garnet). Employs a wavelength of 1,064 nm and a pulse duration of 10 to 100 ms with a cool contact glass cooling system. This is the only laser proven safe and effective for all skin types.
  
  
• Pulsed light. These are not lasers but employ a wide spectrum of light. Wavelengths are between 590 and 1,200 nm and pulse durations are variable. A variety of cooling systems may be used.

It is important for any patient interested in laser hair removal to find a dermatologist and technician with experience in the treatment. Patients should also maintain realistic expectations and clear understandings of the risks and potential side effects. Treatment by spa technicians and other non-medical personnel is not advised.

During an initial consultation, the physician determines the most ideal laser device to use and provides a prediction of the outcome of the treatment. The patient’s medical history is collected and the physician evaluates the patient's skin type and hair color, as well as the coarseness of the targeted area. A history of previous hair-removal treatments including methods used (e.g., shaving, plucking, waxing, depilatory creams, electrolysis, lasers), frequency, last treatment date and response is considered.

A spot test in a small site is generally done to assess the patient’s response to laser hair removal and to determine the setting for laser treatment. The best sites for this test are in low-visibility areas with the same skin type as the area intended for treatment. To assess patient reactions and how effective the treatment is likely to be, at least three days typically pass before re-examination.

Laser hair removal is avoided in patients with active skin infections. Those with a history of herpes simplex virus may require antiviral medications and certain other infections may require antibiotics starting one day prior to treatment to reduce the chance of an outbreak. Antibiotics may also be prescribed prior to laser hair removal if the nasal (around the nose) or perianal (around the anus) areas are involved.

If the patient has used the oral retinoid isotretinoin in the past year, a risk for atypical scarring exists and treatment is postponed until sufficient time has passed (usually six to 12 months). Certain skin diseases (e.g., psoriasis, vitiligo) may be at risk of flares following laser hair removal.

Patients may be told to avoid certain medications (e.g., nonsteroidal anti-inflammatory drugs) and dietary supplements (e.g., niacin, vitamin E) for several weeks prior to treatment. Waxing, plucking or electrolysis needs to be avoided for at least six weeks before treatment, but shaving and depilatory creams may be used without problems. The area to be treated is shaved or depilatory creams are used one day prior to treatment. Alternatively, scissors may be used to trim the hair to just a few millimeters above the skin’s surface.

Tanning makes the hair follicle less responsive to laser hair removal and increases the risk of adverse effects. Hyperpigmentation (darkening) of the skin may occur in patients with a dark tan and the tan may absorb the laser more than the hair, making the treatment ineffective. Because of this, treatment must be postponed until the tan has completely faded and the use of sunscreens is encouraged. In addition, patients should avoid the use of sunless tanning products prior to treatment. Patients with darkly-pigmented skin can be pretreated with topical tretinoin (a retinoid) or bleaching creams to lighten their skin prior to treatment.

Individuals may also be instructed to arrive with a clean and cosmetic-free face on the day of the treatment.

Laser hair removal involves the thermal (heat) destruction of hair follicles by targeting the pigment melanin. The treatments vary depending on the patient. The highest tolerable fluence (density of light) and largest spot size are generally recommended for best results. However, excessive fluence may cause adverse effects.

Anesthesia is usually used only when sensitive areas are treated (e.g., upper lip, bikini line), although it may be used for some patients regardless of the treated area. A topical anesthetic cream is applied one to two hours prior to treatment and wiped off just before treatment.

Selective cooling of the top skin layer (epidermis) helps to reduce skin injury, while enabling the laser to penetrate deeper into the skin. Cooling systems that may be used include:

• Refrigerated aqueous gel. A thick layer of cooled gel is applied before the delivery of laser pulses.
  
  
• Conductive cooling. A chilled glass or sapphire window hand piece is placed directly on the skin.
  
  
• Evaporative or dynamic cooling. Short bursts of cryogen (cold liquid) are delivered automatically before the delivery of each laser pulse.
  
  
• Chilled air cooling. Chilled air is circulated over the skin by means of a hand piece.

During the laser treatment, the technician, patient and others within the room must wear eye protection to prevent the laser from penetrating their eyes and causing damage. The treatment itself feels like a rubber band snapping or warm pinpricks against the skin. Mild to moderate pain may be normal in some patients. However, intense pain may signal other problems and must be immediately reported. In these cases, the treatment may be immediately stopped. Pain often signals that the laser’s settings need to be adjusted.

The duration of the treatment depends on the size of the area treated and may last from a few minutes to several hours. With each light pulse, the targeted hair shaft is immediately vaporized. The plume produced by this has a characteristic sulfurous smell. Laser vacuums are typically used to reduce the odor.

Erythema (redness), swelling and occasionally pain develop immediately after laser hair removal and may last from several days to weeks. Cool compresses, gel packs and ice packs typically help reduce these effects. Over-the-counter pain medications can also be used to relieve pain. Topical corticosteroids may be used for the first day or two following treatment to reduce the development of other adverse effects and topical emollients may be used to maintain skin moisture.

Hair will be shed from the targeted area in the first couple of weeks. Epidermal injury (e.g., blistering, crusting) is rare but may occur. Saline (salt) soaks and topical antibiotics may be used to treat such injury.

The patient can return to normal activities immediately, but avoidance of direct sun exposure is generally recommended for at least a week and a sunscreen with a high sun protection factor (SPF) needs to be applied regularly.

Laser hair removal provides the permanent elimination of some but not all hairs. About 20 percent of all hair is in the resting phase (a phase in which the hair is less responsive to laser hair treatments), therefore complete removal is impossible. At best, 80 percent of the targeted hair may be permanently eliminated in some patients after several treatments. Treated hair that does regrow tends to be finer and lighter and the growth is delayed, with a longer delay than most conventional methods of hair removal (e.g., shaving, waxing, depilatory creams). Laser hair removal is less painful and faster than electrolysis.

Erythema (redness), edema (swelling) and pain may last several days to weeks after treatment. Other side effects depend largely on the type of laser and fluence (density of light) used and are rare if the procedure is performed properly by an experienced laser technician. Patients with tans or darkly pigmented skin are more likely to experience adverse effects because the melanin in the skin competes with melanin in the hair follicle to absorb laser light energy.

The most common side effects of laser hair removal are temporary pigment changes. Postinflammatory hyperpigmentation (darkening of the skin following inflammation) and hypopigmentation (lightening of the skin) have been reported. In some cases, bleaching creams or topical tretinoin (a retinoid) may be used to treat hyperpigmentation. A lightening or darkening of tattoos or freckles may also occur.

Other possible adverse reactions include burning, blistering, crusting and scarring. Outbreaks or flares of certain recurrent conditions may also occur, including psoriasis, vitiligo and herpes simplex virus. Some patients may also develop bacterial infections following treatment.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about laser hair removal:

1. Are you experienced with laser hair removal?
   
   
2. Am I a good candidate for laser hair removal?
   
   
3. Are any of my current conditions or medications of any concern regarding this procedure?
   
   
4. What laser would be best for me?
   
   
5. How long will this procedure take?
   
   
6. Can you explain the procedure to me in detail?
   
   
7. Will I experience pain during the procedure? What about after?
   
   
8. What results can I ultimately expect?
   
   
9. How many treatments will I need to achieve maximum results?
   
   
10. What risks do I face by undergoing laser hair removal?
    
    
11. Are there any special steps I should take to prepare for the procedure?
    
    
12. What steps can I take to relieve discomfort following the procedure?