Supplements

magnesium decreases skeletal muscle cramps

In plain terms: Does magnesium stop muscle cramps?

Refuted Supplements 🔬 Includes disconfirming

RefutedContestedStrong support

consensus score -0.74

Probably not—the best evidence (a Cochrane review) finds little to no benefit for the common night-time/idiopathic leg cramps.

📅 Last reviewed: 2026-07-15 ⓘ

Evidence ladder

How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."

Top evidence so far: All trials, pooled (Meta-analysis)

MechanismIn-vitroAnimalObservationalRCTMeta-analysis

How the studies fall

1 support 2 contradict 0 tested null 0 mixed · 3 sources, 3 independent groups

What the evidence shows

Despite heavy marketing, the best evidence is unsupportive for idiopathic/nocturnal cramps in general/older adults: the Cochrane review found magnesium unlikely to provide clinically meaningful benefit. Some individual RCTs of specific formulations (e.g. magnesium oxide monohydrate) report benefit, keeping it from outright refuted, but the consensus leans against.

Cochrane agrees with us see how our grade compares ▾

Cochrane · moderate-certainty Agrees with our grade

for older adults / idiopathic cramps: percentage change in cramp frequency small and not statistically significant)

“It is unlikely that magnesium supplementation provides clinically meaningful cramp prophylaxis to older adults experiencing skeletal muscle cramps. In contrast, for those experiencing pregnancy-associated rest cramps the literature is conflicting and further research in this population is needed. We found no RCTs evaluating magnesium for exercise-associated muscle cramps or disease-state-associated muscle cramps (for example amyotrophic lateral sclerosis/motor neuron disease).”

Why we agree: we reached the same direction independently, from our own appraisal of 3 sources. Two methods landing in the same place is a stronger signal than either alone.

What is Cochrane, and why trust it?

Cochrane produces systematic reviews: instead of running a new study, they gather every trial ever done on a question, judge how well each was run, and pool the results. They take no commercial or industry funding, which is why the medical community treats their reviews as a gold standard — and why we check our own verdicts against theirs.

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The evidence (3)

Source	Grade	Stance	Quality	Finding
Roffe C, Sills S, Crome P, Jones P 2002 · Med Sci Monit	RCT	contradicts	moderate	Double-blind crossover RCT, n=46 non-pregnant adults with regular leg cramps, Mg citrate 300 mg Mg/d vs placebo, 6 wk each (abstract-grade). On cramps the objective endpoints did not reach significance: 'There was a trend towards less cramps on magnesium (p=0.07). There was no difference in cramp severity and duration between the groups.' Medians 5 vs 9 cramps in the placebo-first sequence (n=29) but 9 vs 8 in the magnesium-first sequence (n=17), with 'a highly significant period effect (p=0.008)'. Patient-rated benefit favoured magnesium (78% vs 54%, p=0.03) and the authors conclude magnesium 'may be effective' - but the cramp-count estimate is compatible with no effect, so contradicts on the directional claim; small, underpowered.
Barna O, Lohoida P, Holovchenko Y, Bazylevych A, Velychko V, Hovbakh I, Bula L, Shechter M 2021 · Nutr J	RCT	supports	low	Multicenter double-blind RCT of magnesium oxide monohydrate (enhanced cellular absorption) for nocturnal leg cramps: reduced cramp burden vs placebo.
Garrison SR, Korownyk CS, Kolber MR, Allan GM, Musini VM, Sekhon RK, Dugré N 2020 · Cochrane Database Syst Rev	meta-analysis	contradicts	high	Cochrane review (update): magnesium unlikely to provide clinically meaningful reduction in idiopathic/older-adult muscle cramps; efficacy for cramps remains unproven.

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