A Cochrane review included 7 studies with a total of 220 subjects. High-frequency TENS was shown to be effective for the treatment of dysmenorrhoea by four small trials (pain relief: OR 7.2, 95% CI 3.1 to 16.5; 2 trials, n= 106). Pain was reduced by a WMD of 45.0 (95% CI 22.5 to 67.5; 1 trial) on a VAS. Low-frequency TENS was found to be no more effective in reducing pain than placebo TENS (OR 1.48, 95% CI 0.43 to 5.08)
Comment: The quality of evidence is downgraded by limitations in study quality (unclear allocation concelament and blinding).