Comparison 1. Magnesium versus placebo (idiopathic cramps): efficacy.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Cramp frequency (percentage change from baseline at four weeks)	3	177	Mean Difference (IV, Fixed, 95% CI)	‐9.59 [‐23.14, 3.97]
1.2 Cramp frequency (percentage change from baseline at 12 weeks)	1	43	Mean Difference (IV, Fixed, 95% CI)	‐12.09 [‐40.22, 16.04]
1.3 Cramp frequency (responder analysis at four weeks)	3	177	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.84, 1.29]
1.4 Cramp frequency (responder analysis at 12 weeks)	1	43	Risk Ratio (M‐H, Fixed, 95% CI)	1.22 [0.70, 2.10]
1.5 Cramp frequency (number of cramps per week at four weeks)	5	307	Mean Difference (IV, Fixed, 95% CI)	‐0.18 [‐0.84, 0.49]
1.6 Cramp frequency (number of cramps on treatment at 12 weeks)	1	43	Mean Difference (IV, Fixed, 95% CI)	‐0.84 [‐3.23, 1.55]
1.7 Cramp intensity (pain scale) at four weeks	4	269	Mean Difference (IV, Fixed, 95% CI)	‐0.02 [‐0.16, 0.12]
1.8 Cramp intensity (pain scale) at 12 weeks	1	43	Mean Difference (IV, Fixed, 95% CI)	‐0.18 [‐0.55, 0.19]
1.9 Cramp intensity (moderate or worse) at four weeks	2	91	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.81, 2.21]
1.10 Cramp intensity (moderate or worse) at 12 weeks	1	43	Risk Ratio (M‐H, Fixed, 95% CI)	0.43 [0.04, 4.44]
1.11 Cramp duration ≥ 1 minute at four weeks	1	46	Risk Ratio (M‐H, Fixed, 95% CI)	1.83 [0.74, 4.53]
1.12 Cramp duration ≥ 1 minute at 12 weeks	1	43	Risk Ratio (M‐H, Fixed, 95% CI)	1.57 [0.63, 3.91]