Benign nocturnal leg cramps are a relatively common and bothersome complaint, particularly among the elderly. Careful history taking and physical examination can exclude the majority of disorders in the differential diagnosis. Mechanical treatment of an acute muscle cramp involves stretching of the affected muscle. Prophylaxis includes both mechanical and pharmacologic measures. The efficacy of quinine sulfate has been supported in the majority of well-designed studies, but its use is controversial, and the FDA has banned over-the-counter quinine-based products used for leg cramps. Potentially fatal hypersensitivity reactions and thrombocytopenia can occur with use of quinine.