Photobiomodulation Therapy With Different Wavebands for Hair Loss: A Systematic Review and Meta-Analysis.

BACKGROUND: Photobiomodulation is a promising therapy for hair loss with negligible side effects. However, the reported effects of photobiomodulation therapy for hair loss are inconsistent. OBJECTIVE: To assess the curative effect of photobiomodulation therapy for the treatment of hair loss. METHODS: A systematic review of self-controlled studies and randomized controlled trials was conducted. ScienceDirect, PubMed, and Wiley Online Library were searched from the earliest date to May 30, 2021. RESULTS: Thirty-six studies (966 patients) were included. Two to 4 meta-analyses with different indices were performed separately on 4 groups of studies to test the effectiveness of the following hair loss treatments: ultraviolet light for alopecia areata (AA), red light for androgenetic alopecia (AGA), infrared light for AA, and infrared light for AGA. All meta-analyses showed that treatments were superior to control ( p < .05). CONCLUSION: The meta-analyses strongly suggested that photobiomodulation therapies with ultraviolet and infrared light were effective for treating AA, and photobiomodulation therapies with red light and infrared light were effective for treating AGA.