Effects of Transcutaneous Electrical Nerve Stimulation on Pain and Menstrual Symptoms in Primary Dysmenorrhea: A Placebo-Controlled Study

Abstract

Introduction

Primary dysmenorrhea, with a prevalence of 45% to 95%, is a common gynecological condition that significantly affects women's daily functioning and quality of life.

Methods

This randomized, single-masked study compared the effects of transcutaneous electrical nerve stimulation (TENS) on pain intensity and menstrual symptoms in women with primary dysmenorrhea using a 3-arm design including TENS (n = 31), placebo (n = 31), and no-intervention control (n = 31) groups. TENS was administered in two 20-minute sessions on the same day during the first 3 days of menstruation. Pain intensity was measured using the Visual Analog Scale (VAS), and menstrual symptoms were assessed with the Daily Menstrual Symptom Rating (DMSR) scale. Between-group differences in postintervention outcomes were analyzed using analysis of covariance, adjusting for baseline values. The trial was prospectively registered at ClinicalTrials.gov (NCT06741059).

Results

After baseline adjustment, significant between-group differences were observed in pain intensity and menstrual symptoms. Adjusted posttest VAS scores were lowest in the TENS group, followed by the placebo group and the control group (P < .001), with a large effect size (partial η² = 0.428). Adjusted posttest DMSR scores were significantly lower in the TENS group compared with the control group (P < .01) with a large effect size (partial η² = 0.160); however, no significant difference was observed between the TENS and placebo groups. Pain scores in the placebo group were also lower than those in the control group, indicating a notable placebo effect.

Discussion

TENS represents a safe, accessible, and patient-centered option for short-term menstrual pain management beyond placebo effects in primary dysmenorrhea.