Effect of Low-Power Visible-Light-Activated Photodynamic Therapy (PDT) on Primary Dysmenorrhea: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

Background: Primary dysmenorrhea (PD) is one of the most common complaints in women of childbearing age. Therefore, this trial aimed to assess the efficacy and safety of low-power visible-light-activated photodynamic therapy (PDT) in the treatment of primary dysmenorrhea (PD), and to further investigate their possible mechanisms of action.

Methods: This study was conducted by using a multicenter, randomized, open, parallel control design. Qualified subjects are randomly assigned to two groups: Group A (low-power visible-light-activated PDT group), Group B (placebo group) and are treated with corresponding protocols for three consecutive menstrual cycles. Baseline data are collected during the trial period. Changes in the scores of VAS scales and the fluctuation of pain factors (PGE2, PGF2α) are recorded before and after the treatment for each group. A comparison of effectiveness in pain control and symptom control is made among the two groups.

Results: After treatment, for the PDT group, the scores of VAS scales decline compared with the scores before treatment. The level of pain factors including PGE2 and PGF2α also drops significantly (P < 0.05). There are no serious adverse events during the study.

Conclusion: Low-power visible-light-activated PDT is a new type of treatment for primary dysmenorrhea which is safe, effective and does not affect normal pregnancy preparation. It may exert its therapeutic effect by adjusting downward the level of PGE2, PGF2α in the body. These factors can be used not only to study the treatment mechanism for primary dysmenorrhea, but also to serve as quantitative indicators for objective assessment of whether dysmenorrhea is relieved.