Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Pain
RCT 3-armed trial	180 women, aged 18 to 30 years, with primary dysmenorrhoea	Pain scores, assessed by visual analogue scale (VAS; scale 0–10, higher scores indicating more severe pain) 2 months 3 with Iranian herbal medicine (highly purified saffron, celery seed, and anise) 5 with placebo	P <0.001	Effect size not calculated	Iranian herbal medicine
RCT 3-armed trial	180 women, aged 18 to 30 years, with primary dysmenorrhoea	Pain scores, assessed by VAS (scale 0–10, higher scores indicating more severe pain) 3 months 0.5 with Iranian herbal medicine (highly purified saffron, celery seed, and anise) 6 with placebo	P <0.001	Effect size not calculated	Iranian herbal medicine
RCT 3-armed trial	180 women, aged 18 to 30 years, with primary dysmenorrhoea	Pain duration 2 months 2.3 with Iranian herbal medicine (highly purified saffron, celery seed, and anise) 16.2 with placebo	P <0.001	Effect size not calculated	Iranian herbal medicine
RCT 3-armed trial	180 women, aged 18 to 30 years, with primary dysmenorrhoea	Pain duration 3 months 2.4 hours with Iranian herbal medicine (highly purified saffron, celery seed, and anise) 15.4 hours with placebo	P <0.001	Effect size not calculated	Iranian herbal medicine