Quinine gives the bitter taste to the tonic water that's often used as a mixer with vodka or gin. It is known as an antimalarial treatment and has also been used to treat arthritis and lupus. Some sufferers of restless leg syndrome (RLS) and nighttime leg cramps claim that quinine provides relief, but the Food and Drug Administration (FDA) has issued a warning about serious side effects--even death--associated with quinine use in some people.
What is Quinine?
Quinine is a naturally occurring substance in the bark of the cinchona tree, which is found in the Andes
Mountains of Peru and Ecuador. Quinine was introduced to Europe in the mid-1600s, but after the destruction of many cinchona trees and the resulting rarity of quinine, a way to synthesise quinine was needed. This was not fully accomplished until two molecular chemists, Robert Woodward and William Doering, were able to complete the process in 1944.
Is Tonic Water Safe?
The simple answer is yes. Like any food or drink, tonic water could bring about a reaction in anyone who is sensitive or allergic to quinine. Such instances are rare, however. In the United States, the FDA limits the amount of quinine allowable in tonic water to about one-10th the prescription dose. Manufacturers add just enough quinine to carbonated water to provide that characteristic bitter taste. Sugar, corn syrup and citrus flavours are often added to make tonic water more palatable. Bitter lemon and bitter lime drinks tend to be more popular in Europe than they are in the U.S.
Non-Prescription Quinine: Caution
Many Internet sources offer quinine teas and quinine powder to add to your food. The FDA has issued strong warnings about using such products. Side effects can include vision and hearing problems, headache, irregular heartbeat and even kidney failure. In the U.S., there have been about 100 quinine-caused deaths over the last 40 years, according to the FDA, and hundreds of permanent injuries. Quinine acts as a mild muscle relaxant in small doses, which is why some say that it is an effective treatment for leg cramps but also the reason that quinine can be dangerous in doses that are not carefully measured and prescribed. Self-medication using quinine can be extremely risky, so see your doctor for treatment of conditions where quinine may be prescribed. Quinine is currently approved only for the treatment of malaria in the U.S. In fact, the FDA has banned all but one brand of quinine, Qualaquin, for medicinal use.
The Bottom Line
Drinking tonic water in moderation is fine if you enjoy its taste in soft drinks or cocktails. See your doctor, however, if you are using it to treat leg cramps, as there may be other products available. Don't buy off-brand quinine from the Internet or from vendors outside the United States.