Laser hair removal
Encyclopedia
Laser hair removal was performed experimentally for about 20 years before it became commercially available in the mid 1990s. One of the first published articles describing laser hair removal was authored by the group at Massachusetts General Hospital
in 1998. The efficacy of laser hair removal is now generally accepted in the dermatology
community, and laser hair removal is widely practiced in clinics, and even in homes using devices designed and priced for consumer self-treatment. Many reviews of laser hair removal methods, safety, and efficacy have been published in the dermatology literature.
hair
removal is selective photothermolysis (SPTL), the matching of a specific wavelength
of light
and pulse duration to obtain optimal effect on a targeted tissue with minimal effect on surrounding tissue. Lasers can cause localized damage by selectively heating dark target matter, melanin
, in the area that causes hair growth, the follicle
, while not heating the rest of the skin
. Light is absorbed by dark objects, so laser energy can be absorbed by dark material in the skin
, but with much more speed and intensity. This dark target matter, or chromophore, can be naturally-occurring or artificially introduced.
Melanin
is considered the primary chromophore
for all hair removal lasers currently on the market. Melanin occurs naturally in the skin, and gives skin and hair their color. There are two types of melanin in hair. Eumelanin gives hair brown or black color, while pheomelanin gives hair blonde or red color. Because of the selective absorption of photon
s of laser light, only black or brown hair can be removed. Laser works best with dark coarse hair. Light skin and dark hair are an ideal combination, being most effective and producing the best results, but new lasers are now able to target dark black hair with some success in patients with dark skin.
Hair removal lasers have been in use since 1997 and have been approved for "permanent hair reduction" in the United States
by the Food and Drug Administration
(FDA). Under the FDA's definition, "permanent" hair reduction is the long-term, stable reduction in the number of hairs regrowing after a treatment regime. Indeed, many patients experience complete regrowth of hair on their treated areas in the years following their last treatment. This means that although laser treatments with these devices will permanently reduce the total number of body hairs, they will not result in a permanent removal of all hair.
Laser hair removal has become popular because of its speed and efficacy, although some of the efficacy is dependent upon the skill and experience of the laser operator, and the choice and availability of different laser technologies used for the procedure. Some will need touch-up treatments, especially on large areas, after the initial set of 3-8 treatments. It has also been noted that some people are "non-responders" – this occurs when the incorrect device is being used, the device parameters are too low or the patient is simply not a good candidate for treatment.
is another hair removal method that has been used for over 135 years. At this time, it is the only permanent option for removal of very fine and light-colored hair. The FDA
currently allows the term "permanent hair removal" for electrolysis only. Unlike laser epilation, electrolysis can be used to remove 100% of the hair from an area and is effective on hair of all colors.
A study conducted in 2000 at the ASVAK Laser Center in Ankara
, Turkey
comparing alexandrite laser and electrolysis for hair removal on 12 patients concluded that laser hair removal was 60 times faster, less painful and more reliable than electrolysis.
Intense pulsed light
(IPL) epilators
, though technically not containing a laser
, use xenon flash lamps that emit full spectrum
light
. IPL-based methods, sometimes called "AFT", "phototricholysis" or "photoepilation", are now commonly (but incorrectly) referred to as "laser hair removal".
radiation
. These lasers are usually defined by the lasing medium used to create the wavelength, measured in nanometers (nm):
Pulse width (or duration) is an important consideration. Longer pulse widths may be safer for darker skin, but shorter pulse widths are more effective in disabling hair follicles. Repetition rate is believed to have a cumulative effect, based on the concept of thermal relaxation time. Shooting two or three pulses at the same target with a specific delay between pulses can cause a slight improvement in the heating of an area. This may increase the "kill rate" for each treatment.
Spot size, or the width of the laser beam, affects treatment. Theoretically, the width of the ideal beam is about four times as wide as the target is deep. Hair removal lasers have a spot size about the size of a fingertip (8-18mm). Larger spot sizes help laser light penetrate deeper and make treatments faster and more effective.
Fluence
or energy level is another important consideration. Fluence is measured in joule
s per square centimeter (J/cm²). It's important to get treated at high enough settings to heat up the follicles enough to disable them from producing hair.
Epidermal cooling has been determined to allow higher fluences and reduce pain and side effects, especially in darker skin. Three types of cooling have been developed:
, and gender. Coarse dark hair on light skin is easiest to treat. Certain areas (notably men's faces) may require considerably more treatments to achieve desired results. Hair grows in several phases (anagen, telogen, catagen) and a laser can only affect the currently active growing hair follicle
s (anagen). Hence, several sessions are needed to kill hair in all phases of growth. This problem is countered by spacing appointments sufficiently so that inactive follicles will start to grow again. Laser does not work well on light-colored hair, red hair, grey hair, white hair, as well as fine hair of any color, such as vellus
. For darker skin patients with black hair, the long-pulsed Nd:YAG laser
with a cooling tip can be safe and effective when used by an experienced practitioner.
, commonly called "ingrown hair
s" or "shaving bumps". They have recently been reported as helpful treatment for pilonidal cyst
s, since they eliminate the ingrown hairs that produce the troublesome foreign body reactions in this congenital malady.
Some level of pain should also be expected during treatments. Numbing creams are available at most clinics, sometimes for an additional cost. Some numbing creams are available over the counter. Use of strong numbing creams over large skin areas being treated at one time must be avoided, as this has seriously harmed, and even killed, patients. Typically, the cream should be applied about 30 minutes before the procedure. Icing the area after the treatment helps relieve the side effects faster.
Unwanted side effects such as hypo- or hyper-pigmentation or, in extreme cases, burning of the skin call for an adjustment in laser selection or settings. Risks include the chance of burning the skin or discoloration of the skin, hypopigmentation
(white spots), flare of acne
, swelling around the hair follicle, scab
formation, purpura
, and infection
. These risks can be reduced by treatment with an appropriate laser type used at appropriate settings for the individual's skin type and treatment area.
Some patients may show side effects from an allergy
to either the hair removal gel used with certain laser types or to a numbing cream.
Rare side effects include blistering, scarring and skin texture changes.
Massachusetts General Hospital
Massachusetts General Hospital is a teaching hospital and biomedical research facility in the West End neighborhood of Boston, Massachusetts...
in 1998. The efficacy of laser hair removal is now generally accepted in the dermatology
Dermatology
Dermatology is the branch of medicine dealing with the skin and its diseases, a unique specialty with both medical and surgical aspects. A dermatologist takes care of diseases, in the widest sense, and some cosmetic problems of the skin, scalp, hair, and nails....
community, and laser hair removal is widely practiced in clinics, and even in homes using devices designed and priced for consumer self-treatment. Many reviews of laser hair removal methods, safety, and efficacy have been published in the dermatology literature.
Mechanism of action
The primary principle behind laserLaser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
hair
Hair
Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
removal is selective photothermolysis (SPTL), the matching of a specific wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
and pulse duration to obtain optimal effect on a targeted tissue with minimal effect on surrounding tissue. Lasers can cause localized damage by selectively heating dark target matter, melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
, in the area that causes hair growth, the follicle
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
, while not heating the rest of the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
. Light is absorbed by dark objects, so laser energy can be absorbed by dark material in the skin
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...
, but with much more speed and intensity. This dark target matter, or chromophore, can be naturally-occurring or artificially introduced.
Melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
is considered the primary chromophore
Chromophore
A chromophore is the part of a molecule responsible for its color. The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls...
for all hair removal lasers currently on the market. Melanin occurs naturally in the skin, and gives skin and hair their color. There are two types of melanin in hair. Eumelanin gives hair brown or black color, while pheomelanin gives hair blonde or red color. Because of the selective absorption of photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s of laser light, only black or brown hair can be removed. Laser works best with dark coarse hair. Light skin and dark hair are an ideal combination, being most effective and producing the best results, but new lasers are now able to target dark black hair with some success in patients with dark skin.
Hair removal lasers have been in use since 1997 and have been approved for "permanent hair reduction" in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
by the Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA). Under the FDA's definition, "permanent" hair reduction is the long-term, stable reduction in the number of hairs regrowing after a treatment regime. Indeed, many patients experience complete regrowth of hair on their treated areas in the years following their last treatment. This means that although laser treatments with these devices will permanently reduce the total number of body hairs, they will not result in a permanent removal of all hair.
Laser hair removal has become popular because of its speed and efficacy, although some of the efficacy is dependent upon the skill and experience of the laser operator, and the choice and availability of different laser technologies used for the procedure. Some will need touch-up treatments, especially on large areas, after the initial set of 3-8 treatments. It has also been noted that some people are "non-responders" – this occurs when the incorrect device is being used, the device parameters are too low or the patient is simply not a good candidate for treatment.
Comparison with electrolysis and IPL
ElectrolysisElectrology
Electrology is the practice of electrical epilation to permanently remove human hair. The actual process of removing the hair is referred to as electrolysis.-Overview:...
is another hair removal method that has been used for over 135 years. At this time, it is the only permanent option for removal of very fine and light-colored hair. The FDA
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
currently allows the term "permanent hair removal" for electrolysis only. Unlike laser epilation, electrolysis can be used to remove 100% of the hair from an area and is effective on hair of all colors.
A study conducted in 2000 at the ASVAK Laser Center in Ankara
Ankara
Ankara is the capital of Turkey and the country's second largest city after Istanbul. The city has a mean elevation of , and as of 2010 the metropolitan area in the entire Ankara Province had a population of 4.4 million....
, Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
comparing alexandrite laser and electrolysis for hair removal on 12 patients concluded that laser hair removal was 60 times faster, less painful and more reliable than electrolysis.
Intense pulsed light
Intense pulsed light
Intense pulsed light , is a technology aimed at producing light of high intensity during a very short period of time. It involves specific lamps together with capacitors whose rapid discharge provides the high energy required....
(IPL) epilators
EPilation
EPilation is the first full-length release from Brisbane musician Tara Simmons. Although a full-length, EPilation contains no new material and is a compilation of Tara's first two EPs Pendulum and All The Amendments...
, though technically not containing a laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
, use xenon flash lamps that emit full spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
. IPL-based methods, sometimes called "AFT", "phototricholysis" or "photoepilation", are now commonly (but incorrectly) referred to as "laser hair removal".
Regulation
In some countries and US states, hair removal is an unregulated procedure that anyone can do. In some places, only doctors and doctor-supervised nurse practitioners can do it while in other cases permission extends to licensed professionals, such as regular nurses, physician assistants, estheticians, and/or cosmetologists. The Florida Board of Medicine has determined that the use of lasers, laser-like devices and intense pulsed light devices is considered the practice of medicine, and requires they be used only by a Physician, an Osteopathic Physician, a Physician Assistant under the supervision of a physician, or an Advanced Registered Nurse Practitioner working under a protocol signed by a Physician.Laser parameters that affect results
Several wavelengths of laser energy have been used for hair removal, from visible light to near-infraredInfrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
. These lasers are usually defined by the lasing medium used to create the wavelength, measured in nanometers (nm):
| Argon: 488 nm (Turquoise/Cyan) or 514.5 nm (Cyan) (no longer used for hair removal) |
| Ruby laser Ruby laser A ruby laser is a solid-state laser that uses a synthetic ruby crystal as its gain medium. The first working laser was a ruby laser made by Theodore H. "Ted" Maiman at Hughes Research Laboratories on May 16, 1960.... : 694.3 nm (Deep Red) (no longer used for hair removal; only safe for patients with very pale skin) |
| Alexandrite: 755 nm (Near-Infrared) (most effective on pale skin and not safe on darker skin at effective settings) |
| Pulsed diode array: 810 nm (Near-Infrared Infrared Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm... ) (for pale to medium type skin) |
| Nd:YAG laser Nd:YAG laser Nd:YAG is a crystal that is used as a lasing medium for solid-state lasers. The dopant, triply ionized neodymium, typically replaces yttrium in the crystal structure of the yttrium aluminium garnet , since they are of similar size... : 1064 nm (Near-Infrared) (made for treating darker skin types, though effective on all skin types) |
Pulse width (or duration) is an important consideration. Longer pulse widths may be safer for darker skin, but shorter pulse widths are more effective in disabling hair follicles. Repetition rate is believed to have a cumulative effect, based on the concept of thermal relaxation time. Shooting two or three pulses at the same target with a specific delay between pulses can cause a slight improvement in the heating of an area. This may increase the "kill rate" for each treatment.
Spot size, or the width of the laser beam, affects treatment. Theoretically, the width of the ideal beam is about four times as wide as the target is deep. Hair removal lasers have a spot size about the size of a fingertip (8-18mm). Larger spot sizes help laser light penetrate deeper and make treatments faster and more effective.
Fluence
Fluence
In physics, fluence is the flux integrated over time. For particles, it is defined as the total number of particles that intersect a unit area in a specific time interval of interest, and has units of m–2...
or energy level is another important consideration. Fluence is measured in joule
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
s per square centimeter (J/cm²). It's important to get treated at high enough settings to heat up the follicles enough to disable them from producing hair.
Epidermal cooling has been determined to allow higher fluences and reduce pain and side effects, especially in darker skin. Three types of cooling have been developed:
- Contact cooling: through a window cooled by circulating water or other internal coolantCoolantA coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...
- Cryogen spray: sprayed directly onto the skin immediately before and/or after the laser pulse
- Air cooling: forced cold air at -34 degrees C (Zimmer Cryo 5 unit)
Number of sessions
Multiple treatments depending on the type of hair and skin color have been shown to provide long-term reduction of hair. Most patients need a minimum of seven treatments. Current parameters differ from device to device but manufacturers and clinicians generally recommend waiting from three to eight weeks depending on the area being treated. The number of sessions depends on various parameters, including the area of the body being treated, skin color, coarseness of hair, reason for hirsutismHirsutism
Hirsutism or frazonism is the excessive hairiness on women in those parts of the body where terminal hair does not normally occur or is minimal - for example, a beard or chest hair. It refers to a male pattern of body hair and it is therefore primarily of cosmetic and psychological concern...
, and gender. Coarse dark hair on light skin is easiest to treat. Certain areas (notably men's faces) may require considerably more treatments to achieve desired results. Hair grows in several phases (anagen, telogen, catagen) and a laser can only affect the currently active growing hair follicle
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
s (anagen). Hence, several sessions are needed to kill hair in all phases of growth. This problem is countered by spacing appointments sufficiently so that inactive follicles will start to grow again. Laser does not work well on light-colored hair, red hair, grey hair, white hair, as well as fine hair of any color, such as vellus
Vellus
Vellus hair, colloquially called 'peach fuzz' or 'bum fluff', is short, fine, light-colored, and barely noticeable hair that develops on most of a person's body from his/her childhood. Exceptions include the lips, the back of the ear, the palm of the hand, the sole of the foot, some external...
. For darker skin patients with black hair, the long-pulsed Nd:YAG laser
Nd:YAG laser
Nd:YAG is a crystal that is used as a lasing medium for solid-state lasers. The dopant, triply ionized neodymium, typically replaces yttrium in the crystal structure of the yttrium aluminium garnet , since they are of similar size...
with a cooling tip can be safe and effective when used by an experienced practitioner.
Intervals between sessions
Usually treatments are spaced three to eight weeks apart depending on the body area and the hair cycle length for that area. The face usually requires more frequent treatments three to four weeks apart, whereas legs require less frequent treatments and patients should be advised to wait at least six weeks. Typically the shedding of the treated hairs takes about two to three weeks. These hairs should be allowed to fall out on their own and should not be manipulated by the patient.Other uses
Hair removal lasers are effective treatment for pseudofolliculitis barbaePseudofolliculitis barbae
Pseudofolliculitis barbae , also known as barber's itch, folliculitis barbae traumatica, razor bumps, scarring pseudofolliculitis of the beard, and shave bumps, is a medical term for persistent irritation caused by shaving....
, commonly called "ingrown hair
Ingrown hair
Ingrown hair is a condition where the hair curls back or grows sideways into the skin. The ingrown hair condition is seen primarily among people having curly hair. It may or may not be accompanied by an infection of the hair follicle or "razor bumps" , which vary in size...
s" or "shaving bumps". They have recently been reported as helpful treatment for pilonidal cyst
Pilonidal cyst
A pilonidal cyst, also referred to as a pilonidal abscess, pilonidal sinus or sacrococcygeal fistula, is a cyst or abscess near or on the natal cleft of the buttocks that often contains hair and skin debris.-Etymology:...
s, since they eliminate the ingrown hairs that produce the troublesome foreign body reactions in this congenital malady.
Side effects and risks
Some normal side effects may occur after laser hair removal treatments, including itching, redness, and swelling around the treatment area. These side effects rarely last more than three days. The most common serious side effect is change in skin pigment.Some level of pain should also be expected during treatments. Numbing creams are available at most clinics, sometimes for an additional cost. Some numbing creams are available over the counter. Use of strong numbing creams over large skin areas being treated at one time must be avoided, as this has seriously harmed, and even killed, patients. Typically, the cream should be applied about 30 minutes before the procedure. Icing the area after the treatment helps relieve the side effects faster.
Unwanted side effects such as hypo- or hyper-pigmentation or, in extreme cases, burning of the skin call for an adjustment in laser selection or settings. Risks include the chance of burning the skin or discoloration of the skin, hypopigmentation
Hypopigmentation
Hypopigmentation is the loss of skin color. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin.-Treatments:...
(white spots), flare of acne
Acne
Acne is a general term used for acneiform eruptions. It is usually used as a synonym for acne vulgaris, but may also refer to:*Acne aestivalis*Acne conglobata*Acne cosmetica*Acne fulminans*Acne keloidalis nuchae*Acne mechanica...
, swelling around the hair follicle, scab
Wound healing
Wound healing, or cicatrisation, is an intricate process in which the skin repairs itself after injury. In normal skin, the epidermis and dermis exists in a steady-state equilibrium, forming a protective barrier against the external environment...
formation, purpura
Purpura
Purpura is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin...
, and infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
. These risks can be reduced by treatment with an appropriate laser type used at appropriate settings for the individual's skin type and treatment area.
Some patients may show side effects from an allergy
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
to either the hair removal gel used with certain laser types or to a numbing cream.
Rare side effects include blistering, scarring and skin texture changes.