Efficacy of herbal medicine (cinnamon/fennel/ginger) for primary dysmenorrhea: a systematic review and meta-analysis of randomized controlled trials

Objective To assess the efficacy of herbal medicine (cinnamon/fennel/ginger) for treating primary dysmenorrhea. Methods Relevant studies were searched in multiple databases. The weighted mean difference (WMD) was used as the effect indicator for measurement data, and each effect size was given estimates and 95% confidence intervals (CIs). Results Nine studies with 647 patients were selected. Compared with the results in the control group, pain intensity was significantly relieved in the trial group when assessed by the intervention (cinnamonvs.placebo: WMD = 1.815, 95% CI = 1.330-2.301; fennelvs.placebo: WMD = 0.528, 95% CI = 0.119-6.829; gingervs.placebo: WMD = 2.902, 95% CI = 2.039-3.765), observation period (one cycle: WMD = 2.061, 95% CI = 0.815-3.307; one cycles: WMD = 1.831, 95% CI = 0.973-2.690), and study quality (high quality: WMD = 2.224, 95% CI = 1.488-2.960). Pain duration was significantly shorter in the trial group (cinnamonvs.placebo: WMD = 16.200, 95% CI = 15.271-17.129). No publication bias was observed for either outcome. Conclusions For primary dysmenorrhea, cinnamon/fennel/ginger effectively reduced pain intensity, and cinnamon shortened the duration of pain. Further studies are needed to confirm our results.