Background Leg cramps are a common complaint, debilitating through pain and loss of sleep. Although sometimes an identifiable treatable cause may be found, often they remain idiopathic . Quinine is traditionally used in this situation, and continues to be widely prescribed in the UK despite its use for this indication being under FDA warning in the USA regarding it's side effects . Some are serious and unpredictable (such as life-threatening thrombocytopenia, occurring as an idiosyncratic hypersensitivity reaction), and the gap between therapeutic and potentially fatal doses is small, with the lowest fatal overdose occurring at 1.5g. Other concerns include it's effect on lengthening the QTc, and interactions with any other medications also metabolised by cytochrome P450 . No other medications are licensed for treatment of leg cramps in the UK.
Results A 68yr old lady who had suffered leg cramps previously unresponsive to treatment with quinine attended her clinic appointment (for RA follow-up). She reported complete relief of her leg cramping symptoms. This was accompanied by a significant improvement in sleep quality as it was no longer disrupted by pain from the cramps. She had heard about, and subsequently tried, a treatment whereby a bar of soap (Imperial Leather, in this case) is placed near the affected limb between the bed sheets overnight. Her symptoms resolved completely. Four further patients report similar findings, and a fifth reports improvement in symptoms of restless legs. No side effects are reported.
Discussion: The effect of soap on leg cramps as a “home remedy” is widely documented on the internet, but relatively little formal research has been conducted. It is theorised that the scented oils in the soap are the active ingredients in this regard. Soaps that are preferred (Ivory, Imperial Leather and Irish Spring) are indeed all scented. Reports that the soap “wears out” over time but re-gains its potency if the surface of the soap is cut or scrapped also broadly support this. A small study in the use of these soap oils for the treatment of menstrual cramps used the oils in a “soap patch” having extracted them from the soap . They report marked analgesic effects in 11 patients for whom both more traditional treatment with nonsteroidals for dysmenorrhoea and homeopathic treatments had not been effective. Four of the five oils extracted are noted to have some anti-spasmodic effect in small lab studies, as reported in their WHO monographs .
As medical practitioners we like to have evidence to back up treatments. In this case there is evidence both of benefit and of significant potential harm with the use of quinine. There is anecdotal evidence of benefit with as yet no evidence of harm (the most likely side effect may be an irritant contact dermatitis, but this is not reported in any of these cases) in the case of soap use.
Conclusions Further work still needs to be done, but in the meantime should we opt to suggest treatment with soap, with anecdotal evidence of benefit and no evidence of harm?
J W Winkelman, MD, PhD: Nocturnal Leg Cramps; Up To Date. updated: Dec 04, 2014.
Electronic Medicines Compendium
Yon Doo Ough et al: Soap-Scented Skin Patch for Menstrual Cramps: A Case Series; The Jurnal of Alternative and Complementary Medicine. July 2008, 14(6): 618-618. doi:10.1089/acm.2007.0819.
WHO Monographs on Selected Medicinal Plants www.who.int
Disclosure of Interest None declared