Quinine is kind of dangerous (real risk of multiple organ failure). It's basically an old folk remedy lacking validity. In fact, the FDA banned the marketing of quinine in 1994 due to its toxicity and lack of evidence that it even helps with nocturnal leg cramps. (Procedings of Baylor University Medical Center, 2003 January; 16(1): 21–26. PMCID: PMC1200805) Since 2007, the Food and Drug Administration has recommended that quinine be prescribed only for the prevention and treatment of malaria. For nocturnal leg cramps, "better to rely instead on stretching exercises to flex the legs before bedtime," according to the Mayo Clinic, which also recommends drinking plenty of fluids and eating foods high in potassium. (NY Times 8/5/08) There are certainly much safer and more convincingly effective things to take for leg cramps. Giving elderly patients a vitamin B supplement providing 250 micrograms of B-12, 30 mg of B-6, 5 mg of riboflavin (B-2), and 50 mg of thiamine (B-1) for three months, doctors found that 86 per cent of their patients who took vitamin B complex vitamins enjoyed complete remission for noctural leg cramping. The researchers reported that, in their view, safe and effective vitamin B should be the treatment of choice for nighttime leg pain in older people. (Chan P, Huang TY, Chen YJ, Huang WP, Liu YC. Randomized, double-blind, placebo-controlled study of the safety and efficacy of vitamin B complex in the treatment of nocturnal leg cramps in elderly patients with hypertension. J Clin Pharmacol. 1998 Dec;38(12):1151-4.) [The B vitamins will be found in multiple vitamins and B-Complex vitamins, but some are far weaker than these amounts.] Vitamin E may also be helpful (about 400 IU minimum). (Robert F. Cathcart, III, M.D. The Journal of the American Medical Association, Vol. 219, No. 2.) http://naturalsolutionsradio.com/articles/article.html?id=6614 And another study showed that calcium, magnesium, and B Vitamins were all effective at dramatically reducing or eliminating noctornal leg cramps. (Int J Gynecol Obstet 2006 Aug 17 [e-pub ahead of print]) http://bastyrcenter.org/content/view/1131/ Some people may simply require more than normal of some specific nutrients...probably due to recent medical history, such as GI problems. Muscle cramps can be aggravated by some drugs, but rarely remedied by any drug. After all, all drugs are "controlled substances" precisely because of their known toxicities and side effects.