Muscle cramps can occur anywhere and for many reasons. Quinine has been used to treat cramps of all causes. However, controversy continues about its efficacy and safety. This review was first published in 2010 and searches were updated in 2014.
Three review authors independently selected trials for inclusion, assessed risk of bias and extracted data. We contacted study authors for additional information. We identified 23 trials with a total of 1586 participants. Fifty-eight percent of these participants were from five unpublished studies. Quinine was compared to placebo (20 trials), vitamin E (4 trials), a quinine-vitamin E combination (3 trials). The most commonly used quinine dosage was 300 mg/day (range 200 to 500 mg).
The risk of bias in the trials varied considerably. All 23 trials claimed to be randomized, but only a minority described randomization and allocation concealment adequately.
Compared to placebo, quinine significantly reduced cramp number over two weeks by 28%, cramp intensity by 10%, and cramp days by 20%. Cramp duration was not significantly affected.
A significantly greater number of people suffered minor adverse events on quinine than placebo, mainly gastrointestinal symptoms. Overdoses of quinine have been reported elsewhere to cause potentially fatal adverse effects, but in the included trials there was no significant difference in major adverse events compared with placebo.
There is low quality evidence that quinine (200 mg to 400 mg daily) significantly reduces cramp number and cramp days and moderate quality evidence that quinine reduces cramp intensity. There is moderate quality evidence that with use up to 60 days, the incidence of serious adverse events is not significantly greater than for placebo in the identified trials, but because serious adverse events can be rarely fatal, in some countries prescription of quinine is severely restricted.
I have long used tonic water to treat cramping. Of course, the dosage is much lower than any of these studies. A liter of tonic water contains 83 mg of quinine and I typically recommend 6-8 ounces of tonic water daily. That equals about 20 mg of quinine daily.
Quinine doses in the range of 500-1000 mg are used to prevent malaria.
I first used tonic water to treat cramping with patients taking Coumadin (rat poison) over 30 years ago. Back then they were restricted from taking any mineral supplements (like calcium) or eating a salad. I found that a glass of tonic water daily was quite effective at preventing cramping.
Today, I typically use tonic water as a test for cramping. I advise a patient to buy a six-pack of 8 ounce bottles and drink one a day. If the tonic water is temporarily effective, then some combination of mineral supplement should also work long term. If not, then I look for other solutions.
The Bottom Line:
The quinine in a glass of tonic water daily can be effective as a preventative for cramping, especially short term. If you suffer from leg or back cramps, give it a try. Make sure the bottle says, “contains trace amounts” or less than 2% quinine” as there are artificial tonic water products on the market that contain no quinine.
Source: Cochrane Library