Herbal medicine as a complementary therapy for dysmenorrhea: effects on pain and reduction of analgesic use

Dysmenorrhea is a prevalent gynecological disorder impairing quality of life for women of reproductive age. Although traditional herbal decoctions (THDs) are widely used for dysmenorrhea in Korea, robust real-world evidence regarding their clinical outcomes and safety is limited. This descriptive, hypothesis-generating registry study aimed to examine individualized THDs for dysmenorrhea using registry data from a multicenter observational study.

This multicenter, prospective observational registry study enrolled women aged 19-65 years with dysmenorrhea from 33 traditional Korean medicine (TKM) clinics and one TKM hospital in Korea (July 2022-June 2023). Participants were categorized into a THD group (received THDs for ≥10 days) and a non-THD group. Primary outcomes were changes in pain intensity (Numeric Rating Scale, NRS), duration of menstrual pain, and analgesic consumption (defined as the number of analgesic tablets taken per menstrual cycle), assessed at each visit. To address confounding and selection bias, a difference-in-differences analysis using inverse probability of treatment weighting (IPTW) based on propensity scores was performed. Missing data were handled using complete-case analysis, supported by Little's MCAR test (p = 0.39). Safety was assessed by monitoring and categorizing adverse events.

A total of 119 participants in the THD group and 16 in the non-THD group completed the study. Both groups demonstrated significant within-group reductions in menstrual pain intensity over time. Regarding between-group differences, the THD group showed a significantly greater observed reduction in menstrual pain intensity at visit 2 compared to the non-THD group (Estimate = -1.41, p = 0.029); no significant between-group difference was observed at other time points. Analgesic use also showed a statistically significant observed decrease in the THD group at visit 2 (Estimate = -1.63, p = 0.001). No statistically significant between-group difference was identified for pain duration at any time point. Mild adverse events were reported by 9 participants (7.6%) in the THD group; all resolved spontaneously. No adverse events occurred in the non-THD group.

These preliminary findings suggest that individualized THDs may be associated with reduced menstrual pain intensity and analgesic consumption in women with dysmenorrhea in real-world settings; however, significant between-group differences were observed at a single time point only, pain duration did not differ significantly between groups, and comparative safety conclusions remain constrained by the small control group. Larger, adequately powered studies are needed to confirm these exploratory findings.