Bypassing the Heat Risk and Efficacy Limitations of Pulsed 630 Nm LED Photobiomodulation Therapy for Anti-Primary Dysmenorrhea: A Prospective Randomized Cross-Over Trial

In recent years, photobiomodulation (PBM) has attracted widespread attention for the treatment of various causes of pain and inflammation. Primary dysmenorrhea (PD) is a common gynecological condition characterized by severe menstrual pain, and the limited effectiveness and side effects of conventional treatments have highlighted the urgent need to develop and identify new adjunct therapeutic strategies. The present study from the perspective of light morphology aimed to bypass the heat risk limitation and evaluate the efficacy and safety of pulsed 630 nm PBM therapy for reducing pain associated with PD. The pulse light parameters were designed according to the transmittance of red light. In this randomized, cross-over design, sham-controlled study, 46 women with PD were included and randomly assigned to either pulsed 630 nm light therapy or white light sham control therapy. The intervention lasted for 20 min per day and was administered for 7 consecutive days before and during menstruation. The results showed that the pulsed 630 nm PBM treatment demonstrated a significant reduction in pain levels compared to the placebo treatment (p < 0.001), with 55.00% of active treatment participants experiencing a pain intensity differential concentration exceeding 50.00%. Moreover, participants reported an improved quality of life during the active treatment phase and generally preferred it as a more effective method for relieving PD. No adverse events or side effects were reported throughout the trial. Based on the results, pulsed 630 nm LED therapy showed significant relief of menstrual pain compared to white light placebo treatment and improved quality of life under certain circumstances. Therefore, this study proposes that pulsed red light PBM therapy may be a promising approach for future clinical treatment of PD.