Is TENS an effective physical monotherapy for primary dysmenorrhea? A systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to determine the therapeutic efficacy of transcutaneous electrical nerve stimulation (TENS) in women with primary dysmenorrhea. We searched PubMed, Embase, EBSCOhost, and Ovid MEDLINE for randomized controlled trials from inception to 18 December 2024. The risk ratio (RR) or standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated. Heterogeneity was assessed using the I² statistic. Of 139 identified records, 9 articles met inclusion criteria, encompassing 530 women with primary dysmenorrhea. Moderate-quality evidence indicated that significantly fewer women required pain medication following TENS compared with placebo (RR: 0.43; 95% CI: 0.30 to 0.63; <i>p</i> < 0.0001; I² = 37.22%). Analgesia duration was significantly longer after TENS than placebo (MD: 8.07; 95% CI: 8.05 to 8.09; <i>p</i> < 0.001). No significant differences were observed in pooled menstrual pain intensity (SMD: -4.50; 95% CI: -9.90 to 0.91; <i>p</i> = 0.1) or in the number of women reporting adverse effects (RR: 2.89; 95% CI: 0.40 to 20.88; <i>p</i> = 0.29; I² = 0%) between TENS and placebo groups. This meta-analysis should be interpreted cautiously due to limited evidence quality and the small number of included studies.<b>Protocol registration</b>: www.crd.york.ac.uk/prospero identifier is CRD420251000666.