Twelve Months of LLLT Show Sustained Benefit in Alopecia

Low-level laser therapy (LLLT) has become an increasingly visible option in the therapeutic landscape for androgenetic alopecia (AGA), particularly for patients seeking nonpharmacologic or adjunctive approaches. While short-term randomized trials have demonstrated modest efficacy, questions have persisted regarding durability of response and long-term safety.¹ A recently published 12-month prospective study by Shin et al, published in Dermatologic Therapy, helps address this gap by evaluating sustained outcomes with a home-use helmet-type LLLT device in both men and women with AGA.²

Study design and population

This multicenter, open-label trial enrolled 68 adults (51 men and 17 women) aged 19 to 65 years with mild to severe AGA. Importantly, participants were either treatment-naïve or had discontinued other hair loss therapies for at least 6 months prior to enrollment, allowing clearer attribution of outcomes to the device.

Participants used a helmet-style LLLT device emitting red light in the 646–675 nm range, 3 times weekly for 20 minutes, over a total of 48 weeks. Objective endpoints included hair density and shaft thickness measured by phototrichogram, with secondary assessments consisting of investigator-rated global photographs and patient-reported outcomes.

Objective efficacy outcomes

Hair density increased progressively over the study period. Mean baseline density of approximately 99 hairs/cm² rose to 124 hairs/cm² at 48 weeks, representing an average gain of 25 hairs/cm², or roughly a 25% increase. Statistically significant improvements were first observed at 16 weeks and continued through 12 months without evidence of plateau. This sustained upward trend is notable, as many prior LLLT studies have been limited to 16-26 weeks.

Hair shaft thickness also improved with continued use. Mean thickness increased from about 65 µm at baseline to nearly 75 µm at week 48, corresponding to an approximate 15% increase. Unlike density, thickness gains became statistically significant later, around the 24-week mark, suggesting that follicular miniaturization may be slower to reverse than hair count changes.

Subgroup analyses showed consistent responses across sex and baseline disease severity. Both men and women experienced comparable increases in density and thickness, and patients with mild, moderate, and even severe AGA demonstrated measurable improvement. Although the severe subgroup was small, the lack of clear attenuation of response across severity levels suggests LLLT may have utility beyond early disease.

Clinical and patient-reported outcomes

Investigator global photographic assessments supported the objective findings. At 48 weeks, nearly 59% of participants were rated as improved, while fewer than 2% showed any visible worsening. Importantly, over 98% demonstrated stabilization or improvement, which contrasts with the expected progressive nature of untreated AGA.

Patient perception mirrored these observations. Self-assessment scores increased steadily over time, with most participants reporting moderate improvement by study end. More than 85% expressed satisfaction with treatment and willingness to continue, highlighting the perceived clinical relevance of the changes, even if absolute gains were modest.

Safety and adherence

One of the most consistent findings was the favorable safety profile. No device-related adverse events were reported over the 12-month period. There were no cases of scalp irritation, burns, or discomfort, and no systemic effects were observed on laboratory monitoring. Adherence was high, averaging over 97%, likely reflecting the convenience of the helmet design and the absence of treatment-related adverse effects.

Context and limitations

While the findings strengthen the evidence base for LLLT, several limitations warrant consideration. The open-label design and lack of a sham control introduce the possibility of placebo effects, particularly for subjective outcomes. However, the use of objective phototrichogram measurements and the magnitude of change over a full year argue against spontaneous variation alone. The study also evaluated a single device configuration and treatment schedule, so results cannot be generalized to all LLLT systems.

Clinical implications

For clinicians, this study suggests that LLLT can offer sustained, incremental improvements in hair density and thickness when used consistently over 12 months, with an excellent safety profile. While LLLT is unlikely to replace pharmacologic therapies, it may be particularly valuable for patients who cannot tolerate or prefer to avoid systemic agents, or as an adjunct to established treatments. Long-term data such as these support framing LLLT as a maintenance-oriented therapy, aligned with the chronic nature of AGA, rather than a short-term intervention.

References

1. Perez SM, Vattigunta M, Kelly C, Eber A. Low-level laser and LED therapy in alopecia: A systematic review and meta-analysis. Dermatol Surg. 2025;51(2):179-183. doi:10.1097/DSS.0000000000004442
2. Shin J, Paik K, Na J, Lew B, Huh C. Long-term efficacy and safety of low-level laser therapy for androgenetic alopecia: A 12-month prospective trial. Dermatol Thera. 2026. doi:10.1155/dth/6621458