What is the efficacy of low-level laser therapy (LLLT) for treating hair loss?

Low-Level Laser Therapy for Hair Loss

Low-level laser therapy (LLLT) at 655 nm is an effective treatment option for androgenetic alopecia (AGA) in both men and women, requiring 3 times per week use for continuous benefit, and can be used either as monotherapy or in combination with minoxidil or finasteride. 1

Evidence for Efficacy in Androgenetic Alopecia

LLLT demonstrates consistent efficacy for treating AGA with significant improvements in hair density and thickness. The most robust evidence comes from multiple clinical trials:

• In female pattern hair loss specifically, LLLT at 655 nm significantly improved hair counts from baseline (222.3 ± 33.5 to 255.3 ± 30.4, p = 0.007) after 16 weeks of twice-weekly treatment. 2

• A systematic review of 10 out of 11 clinical trials demonstrated significant improvement in androgenic alopecia compared to baseline or controls when treated with LLLT. 3

• In a retrospective study of 32 patients (21 female, 11 male), 8 showed significant improvement, 20 showed moderate improvement, and only 4 showed no improvement, with benefits observed as early as 3 months and sustained up to 24 months. 4

Treatment Protocol

The standard regimen requires 3 times per week application for continuous effectiveness, as recommended in current guidelines. 1

• Treatment sessions typically last 20 minutes per session using 655 nm wavelength devices (helmet-type or comb devices). 2, 4

• Patients should be counseled that visible improvement requires 3-4 months of consistent use, similar to minoxidil. 1

• LLLT must be continued long-term to maintain benefits, as discontinuation results in loss of gains. 1

Combination Therapy

LLLT can be effectively combined with minoxidil or finasteride, potentially acting synergistically to enhance hair growth. 4, 3

• Two clinical trials demonstrated efficacy for LLLT in combination with topical minoxidil, and one trial showed efficacy when accompanying finasteride treatment. 3

• This makes LLLT particularly valuable for patients who have partial response to medical therapy and want to optimize results without adding systemic medications. 4

Limited Evidence for Other Hair Loss Types

For alopecia areata, the evidence is weaker and based only on small uncontrolled studies (level of evidence 3). 1

• In patchy alopecia areata, infrared diode laser showed complete or partial regrowth in 32 of 34 treated patches, while untreated patches showed no growth. 1

• A 308-nm excimer laser treated twice weekly for 12 weeks showed regrowth in 17 of 42 patches (60% response rate) in adults, with similar results in children. 1

• However, these studies lack the rigor of randomized controlled trials and should not be considered first-line therapy for alopecia areata. 1

For telogen effluvium, LLLT showed no statistically significant benefit (baseline 271.2 ± 39.0 to 294.2 ± 38.1, p = 0.143). 2

Critical Limitations and Caveats

The major limitation is lack of standardization across studies, making direct comparisons difficult:

• Study durations vary widely, sample sizes are often small, and efficacy measurements are inconsistent across trials. 5

• Many studies lack visual photographic evidence and blinded evaluation, which are critical for objective assessment. 6, 5

• One early study found increases in terminal hair counts and shaft diameter that failed to reach statistical significance, and blinded evaluation of global images did not support improvement. 6

• The optimal power, wavelength, and treatment frequency remain incompletely defined, though 655 nm appears most studied. 3

Safety Profile

LLLT has an excellent safety profile with no serious adverse events reported across multiple studies. 2, 4

• No adverse reactions were reported in the 32-patient retrospective study with follow-up extending to 24 months. 4

• This makes LLLT particularly attractive for patients who cannot tolerate or refuse systemic medications like finasteride. 4, 3

Clinical Decision Algorithm

Use LLLT in the following scenarios:

1. As monotherapy for patients who refuse or cannot tolerate minoxidil/finasteride 4, 3
2. As adjunctive therapy to enhance results in patients with partial response to medical therapy 4, 3
3. For female patients who prefer non-pharmacologic options 2

Do not use LLLT as first-line for:

• Drug-induced telogen effluvium (including from weight loss medications), where it shows no significant benefit 2
• Alopecia areata, where evidence is insufficient and other treatments are preferred 1

Key pitfall to avoid: Do not promise rapid results. Set realistic expectations that improvement takes 3-4 months minimum, and emphasize the need for indefinite continuation to maintain benefits. 1, 4