The effect of magnesium infusion on rest cramps: randomized controlled trial.

Study answer

What this study found

Intravenous magnesium did not reduce rest cramp frequency versus placebo, so the intervention was not effective for cramp prophylaxis in this geriatric population. The primary outcome changed by -2.4 cramps per week in the magnesium group versus -1.7 in the placebo group (p = .51; 95% CI for the difference -3.1 to 1.7). Percentage change in cramps was also similar (-26.8% vs -21.3%; p = .71; 95% CI difference -35.0 to 23.9). Magnesium retention did not predict response, with no correlation between percent retention and change in cramp rate. Reported adverse events included infusion-site…

Study & population

This was a double-blind randomized placebo-controlled trial in independent, community-dwelling older adults with rest cramps.

Intervention

Intravenous magnesium sulfate was given as 20 mmol (5 g) per infusion in 250 mL D5W over 4 hours on 5 consecutive days (Monday to Friday), compared with placebo infusion.

Key limitation

The trial was small and had limited power to detect modest benefits.

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Original abstract