Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
Systematic review	People with nocturnal leg cramps 8 RCTs in this analysis	Tinnitus 20/659 (3%) with quinine 7/659 (1%) with placebo	RR 2.86 95% CI 1.22 to 6.71 NNH 50 95% CI 27 to 230	Moderate effect size	placebo
Systematic review	People with cramps 16 RCTs in this analysis	Minor adverse events 93/725 (13%) with quinine 68/722 (9%) with placebo	Risk difference 0.03% 95% CI 0.00% to 0.06% P = 0.026	Effect size not calculated	placebo
Systematic review	People with cramps 18 RCTs in this analysis	Major adverse events 12/806 (1%) with quinine 11/807 (1%) with placebo	Risk difference 0.00% 95% CI –0.01% to +0.02% P = 0.86		Not significant
Systematic review	People with cramps 18 RCTs in this analysis	Gastrointestinal adverse effects 39/790 (5%) with quinine 16/791 (2%) with placebo	Risk difference 0.03% 95% CI 0.01% to 0.05% P = 0.003	Effect size not calculated	placebo
Systematic review	People with cramps 18 RCTs in this analysis	Tinnitus 10/790 (1%) with quinine 1/791 (0%) with placebo	Risk difference 0.01% 95% CI 0.00% to 0.02% P = 0.083		Not significant