Garrison et al. 2020, magnesium for skeletal muscle cramps (Cochrane)

Cochrane systematic review (CD009402.pub3) of magnesium supplementation for skeletal muscle cramps. It concluded that magnesium is unlikely to be effective for idiopathic cramps at any dose or route tested. No trials of people who cramp while exercising were found, so there is no direct evidence for exercise-associated cramp at all. Minor side effects, chiefly diarrhoea and nausea, were common. Undercuts the widespread marketing of magnesium as a cramp remedy for athletes.