A Cochrane review included 80 RCTs involving a total of 5 820 women. In women with dysmenorrhoea, NSAIDs were found significantly more effective for pain relief than placebo (OR 4.37, 95% CI 3.76 to 5.09; 35 trials, I²=53%) or paracetamol (OR 1.89, 95% CI 1.05 to 3.44; 3 trials, I²=0%), though overall adverse effects were also significantly more common with NSAIDs vs placebo (OR 1.29, 95% CI 1.11 to 1.51; 25 trials). When NSAIDs were compared with each other, there was little evidence of the superiority of any individual NSAID with regard to either efficacy or safety. There was no evidence that COX-2-specific inhibitors were more effective or tolerable for the treatment of dysmenorrhoea than traditional NSAIDs; however data were very scanty (only 2 trials).