Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
Systematic review	599 women with moderate to severe pain 14 RCTs in this analysis	Adverse effects with NSAIDs with placebo	RR (NSAIDs [analysed as a group] v placebo) 1.29 95% CI 1.05 to 1.59 However, no significant difference between any 1 NSAID and placebo	Small effect size	placebo
RCT Crossover design 5-armed trial	104 women with primary dysmenorrhoea	Adverse effects with ibuprofen arginate 200 mg with ibuprofen arginate 400 mg with ibuprofen 200 mg with ibuprofen 400 mg with placebo Absolute results not reported	Reported as no significant difference between active treatments and placebo		Not significant
RCT Crossover design 3-armed trial	73 women with moderate to severe primary dysmenorrhoea	Incidence of adverse effects 12% with etoricoxib 25% with naproxen sodium 15% with placebo Absolute numbers not reported	Significance assessment not performed
RCT Crossover design 3-armed trial	73 women with moderate to severe primary dysmenorrhoea	Headache 1.5% with etoricoxib 7.5% with naproxen sodium 4.5% with placebo Absolute numbers not reported	Significance assessment not performed
RCT Crossover design 3-armed trial	73 women with moderate to severe primary dysmenorrhoea	Nausea 3% with etoricoxib 3% with naproxen sodium 1.5% with placebo Absolute numbers not reported	Significance assessment not performed
RCT Crossover design 4-armed trial	144 women with moderate to severe primary dysmenorrhoea	Proportion of people reporting adverse effects 23% with naproxen 13% with placebo Absolute numbers not reported	Significance assessment not reported
RCT Crossover design 3-armed trial	149 women aged between 18 and 44 years, with primary dysmenorrhoea	Adverse effects 40/129 (31%) with celecoxib 46/126 (37%) with naproxen sodium 38/127 (30%) with placebo
RCT 3-armed trial	180 women with primary dysmenorrhoea	Adverse effects with mefenamic acid with placebo