What was tested
The trial compared red LEDs, blue LEDs, both colours together, and a sham cap. A sham looks like a treatment but is used as a comparison. Sessions lasted ten minutes daily.
The result that needs care
Of 160 people assigned treatment, 91 were excluded from the per-protocol analysis. That analysis required completing sixteen weeks, avoiding major protocol problems, and following at least 80% of sessions.
Separate groups versus a combined group
The individual active groups did not reach statistical significance for the main sixteen-week hair-count outcome. Pooling the three active groups produced a significant difference from sham: 28.5 more hairs per cm².
What it cannot show
The combined result does not establish which colour performed best. The exclusions also matter when judging how the finding applies to everyday users.
Read the paper
Thomas M et al. Dermatologic Surgery. 2025;51(4):416–421.
Clinical Safety and Efficacy of Dual Wavelength Low-Level Light Therapy in Androgenetic Alopecia
PMID 39679573 · DOI 10.1097/DSS.0000000000004509
This note explains the published abstract. It is not a review of the full paper or personal medical advice. Published 1 November 2026.