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REVIEW ARTICLE
Low level laser therapy and hair regrowth:
an evidence-based review
Mina Zarei
1
&Tongyu C. Wikramanayake
1
&Leyre Falto-Aizpurua
1
&
Lawrence A. Schachner
1
&Joaquin J. Jimenez
1
Received: 23 February 2015 /Accepted: 12 October 2015 /Published online: 21 December 2015
#Springer-Verlag London 2015
Abstract Despite the current treatment options for different
types of alopecia, there is a need for more effective management
options. Recently, low-level laser therapy (LLLT) was evaluated
for stimulating hair growth. Here, we reviewed the current evi-
dence on the LLLT effects with an evidence-based approach,
focusing more on randomized controlled studies by critically
evaluating them. In order to investigate whether in individuals
presenting with hair loss (male pattern hair loss (MPHL), female
pattern hair loss (FPHL), alopecia areata (AA), and
chemotherapy-induced alopecia (CIA)) LLLT is effective for
hair regrowth, several databases including PubMed, Google
Scholar, Medline, Embase, and Cochrane Database were
searched using the following keywords: Alopecia, Hair loss,
Hair growth, Low level laser therapy, Low level light therapy,
Low energy laser irradiation, and Photobiomodulation. From
the searches, 21 relevant studies were summarized in this review
including 2 in vitro, 7 animal, and 12 clinical studies. Among
clinical studies, only five were randomized controlled trials
(RCTs), which evaluated LLLT effect on male and female pat-
tern hair loss. The RCTs were critically appraised using the
created checklist according to the Critical Appraisal for Therapy
Articles Worksheet created by the Center of Evidence-Based
Medicine, Oxford. The results demonstrated that all the per-
formed RCTs have moderate to high quality of evidence. How-
ever, only one out of five studies performed intention-to-treat
analysis, and only another study reported the method of random-
ization and subsequent concealment of allocation clearly; all
other studies did not include this very important information in
their reports. None of these studies reported the treatment effect
of factors such as number needed to treat. Based on this review
on all the available evidence about effect of LLLT in alopecia,
we found that the FDA-cleared LLLT devices are both safe and
effective in patients with MPHL and FPHL who did not respond
or were not tolerant to standard treatments. Future randomized
controlled trials of LLLT are strongly encouraged to be conduct-
ed and reported according to the Consolidated Standards of
Reporting Trials (CONSORT) statement to facilitate analysis
and comparison.
Keywords Low-level laser therapy .Hair regrowth .
Evidence-based medicine
Introduction
LLLT and paradoxical hypertrichosis
Low-level laser therapy (LLLT) was discovered in the 1960s
and first used by the National Aeronautics and Space Admin-
istration (NASA) to accelerate wound healing in space [1].
Since then, LLLT devices have been used to induce a variety
of therapeutic effects associated with a range of wavelengths,
from red to infrared. The reported biological effects of low-
energy laser include anti-inflammation, pain reduction, wound
healing, anti-edema, antibiosis, immunity, and local blood cir-
culation improvement which are collectively called
biomodulation effect [2–4]. LLLT is also known as low light
laser therapy, red light therapy, cold laser, and soft laser [1].
One of the traditional uses of laser in dermatology is for
hair removal. Lasers induce this effect by targeting melanin,
which acts as a chromophore. Melanin dissipated the absorbed
*Joaquin J. Jimenez
jjimenez@med.miami.edu
1
Department of Dermatology and Cutaneous Surgery, University of
Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB
2023, Miami, FL 33136, USA
Lasers Med Sci (2016) 31:363–371
DOI 10.1007/s10103-015-1818-2
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