Medical treatment for cramps and restless legs could be putting you at risk for fatal heart problems

A new warning has been issued over quinine, a medicine and ingredient found in beverages like tonic water and bitter lemon.

Long used as a drug for malaria, quinine is no longer a recommended treatment for any condition by the U.K.’s two major healthcare watchdogs. However, that hasn’t stopped doctors in the country from issuing 3.5 million prescriptions for it every year to people who are suffering from issues like cramps, muscle discomfort and restless legs. Doctors are prescribing it off-label for such conditions, and in many cases, patients take it for several years.

Now, researchers from University College London and the Royal Free Medical School have discovered that people who take quinine for more than a year have a 25 percent higher likelihood of early death than those who do not take the drug. Interestingly, those who were younger than 50 had a greater rise in their risk of death than older patients.

The researchers studied those taking prescriptions for quinine of 100 milligrams a day or more over the course of a year or longer. Their findings were published in the Journal of the American Medical Association.

Quinine can cause an abnormal heart rhythm in some people, possibly triggering a heart attack. In addition, it can affect blood clotting, which could lead to a stroke or heart attack from a blocked artery.

Watch out for tonic water, too

While drinking a few gin and tonics here and there might not be problematic on its own, those who are already taking quinine as a medicine need to watch their intake because it could heighten their risk even further. In rare cases, even the small amount found in tonic water could be enough to cause one of quinine’s most serious side effects, a severe drop in blood platelet counts that can cause external and internal bleeding. Another worrying side effect is permanent kidney damage.

It is also worth noting that quinine passes through the placenta and can cause birth defects, which means that pregnant women should avoid it at all costs. In addition, it is known to interact with some common drugs like statins and the heart failure medication digoxin.

It’s also possible to develop an allergy or sensitivity to it even from drinking tonic water occasionally, and taking a medicinal quinine dose years later can trigger a full-blown reaction in such individuals.

Quinine banned in the U.S. as a treatment for leg cramps

The FDA reports that quinine is responsible for 665 adverse events as well as 93 deaths. Doctors in the U.S. have been banned from prescribing it for nighttime leg cramps since 2010. The only condition it is approved to treat by the FDA is malaria, and even then, it is typically only used in cases where newer drugs are not effective.

The study’s author, Irwin Nazareth, said: “My advice to anyone on quinine for these conditions is to stop taking it, and GPs would be well advised not to prescribe quinine.”

Lenox Hill Hospital’s Director of Neurosurgical Pain, Dr. Kiran V. Patel, told CBS News that it’s an old wives’ tale that quinine water can help leg cramps, even though many patients tell her they’ve been drinking tonic water to help ease the condition.

People suffering from restless kegs and cramps can try taking a vitamin B complex supplement instead, and stretching may also help, depending on the cause of the cramps.

Sources include:

DailyMail.co.uk

LiveScience.com

CBSNews.com