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Author: Anoma Ranaweera B.V. Sc; PhD (Clinical Biochemistry, University of Liverpool, UK), 2013.
Low level laser therapy is a safe form of light/heat treatment under investigation for a variety of health indications. It is being used to treat the genetic forms of hair loss common in men and women, androgenetic alopecia or pattern balding.
Low level laser therapy is also called red light therapy, cold laser, soft laser, biostimulation and photobiomodulation.
Androgenetic alopecia can affect up to 70% of men (male pattern balding) and 40% of women (female pattern balding) at some point in their lifetime. While men typically present with a distinctive alopecia pattern involving hairline recession and vertex balding, women normally exhibit a diffuse hair thinning over the top of their scalps. For both men and women, losing their hair is a frustrating experience.
The current treatment standard for pattern balding is therapy with minoxidil and finasteride, with hair transplantation as a surgical option. However, low level laser treatment for hair loss is now also promoted as a safe alternative or additional treatment.
Laser therapy used for hair loss treatment depends on devices that emit a light that can penetrate the scalp. Excimer (308 nm), helium-neon (632.8 nm), and fractional erbium-glass (1550 nm) lasers have been used. Low level laser therapy (LLLT) uses devices with diodes that emit red light (wavelength 630-670 nanometers), or infrared radiation, available as:
The HairMax® LaserComb (Lexington International LLC, USA) was given 501(k) clearance to market by the FDA for the treatment of androgenetic alopecia and promotion of hair growth in men in 2007 and in women in 2011. Battery-powered models have 7, 9 or 12 beams of red light that pass through the teeth of a comb.
The iRestore Hair Growth System with diode red lights and infrared laser was cleared for marketing by the FDA in 2016. It is a head cap indicated to promote hair growth in females with androgenetic alopecia who have Ludwig-Savin Classifications of I- II, males who have Norwood-Hamilton Classifications of lla- V and for both, Fitzpatrick Classification of Skin Phototypes I to IV.
Low level laser therapy is intended for men and women with thinning hair or pattern baldness caused by a hereditary condition.
Physicians use a system known as the Norwood-Hamilton Classification (men) and the Ludwig-Savin Scale (women) to describe the degree of hair loss. Low level laser therapy is intended for promotion of hair growth in males who have Norwood Hamilton Classifications of IIa to V and in females who have Ludwig (Savin) I-4, II-1, II-2, or frontal patterns of hair loss and have Fitzpatrick skin phototypes I to IV.
The hair growth cycle consists of three phases: growth (anagen phase), resting (telogen phase) and shedding (catagen phase). Hair loss in androgenetic alopecia depends on a testosterone derivative in the skin, dihydrotestosterone (DHT). Low level laser therapy is believed to increase blood flow in the scalp and stimulate metabolism in catagen or telogen follicles, resulting in the production of anagen hair. In theory:
Physicians have varying views on whether or not low level laser therapy is effective. While some physicians reject its use entirely, others believe that low level laser therapy can provide benefit for some men and women suffering from androgenic alopecia (genetic baldness). It has also been suggested that it may assist a hair transplant patient’s postoperative wound healing process and expedite hair growth.
In a second study of 103 males and 122 females with pattern alopecia that completed the study, HairMax® LaserComb (with 12, 9 and 7 beams) was reported to result in increase in terminal hair density compared to similar trial subjects treated with a sham device.
Trials are underway to study the efficacy of LaserCap™ (Transdermal Cap, Gates Mills, Ohio), TopHat 655 Rejuvenation System (Apira Science, Newport Beach, California) and Erchronia ML Scanner (Erchronia Corporation, McKinney, Texas) in pattern alopecia and other forms of hair loss. 
However, published trials of low level laser light have been criticised as not being independent and anedotal individual reports of using these devices appears disappointing.
Improvement is reported in at least some users after 12 to 26 weeks of use, with reduced hair fall and noticeable hair growth.
Laser hair therapy may be delivered in a salon by professionals trained in its administration, or at home.
Two to three times weekly treatments are typically recommended, and consist of a 8 to 15-minute exposure of the scalp to light-emitting diodes under a bonnet or head cap or using a handheld comb or brush.
Scalp treatment and massages that promote blood circulation may be used additionally as part of the program.
Proprietors of low level laser therapy services speak about the importance of regularity, which includes frequent appointments (twice a week, more or less) over a long duration (typically one year).
Laser therapy should not be used concomitantly with medications or products that are photosensitising (see drug-induced photosensitivity).
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