Quinine is a substance that was first obtained by processing the bark of the cinchona tree, a South American native plant that has been used as a fever reducer by Native Americans for centuries. This substance has been used historically to treat malaria, along with some other medical conditions, and although a number of antimalarial drugs are on the market today, it is still used in some regions. It is also used commercially as an additive to tonic water, a soft drink that is used as a mixer for other drinks in addition to being consumed straight.
Europeans were introduced to quinine in the 1600s, when Jesuit missionaries first brought the “miracle bark” to Europe from their South American missions. When Europeans began using the drug to treat the fevers associated with malaria, they discovered that it was highly effective against certain strains, and Jesuit missions soon began making money from their operations. Through the 1930s, it was the only drug effective against malaria, until an assortment of other antimalarials were developed to combat the disease.
In pure form, quinine is a white to colorless crystalline powder with a sharply bitter taste. This bitterness is famous; it's what gives tonic water its classic flavor, and it was the bane of many residents of the tropics, where quinine was taken as a prophylactic to prevent malaria infection. Tonic water was, in fact, originally developed as a prophylactic antimalarial drug, and many people added things like gin to make the tonic more palatable.
Modern tonic water does not usually contain enough of this substance to be useful as a prophylactic against malaria, although it retains the bitter flavor. Quinine for the treatment and prevention of malaria can be purchased in the form of tablets and liquid medications. The drug is also used to treat muscle cramps and fever, and it has historically been used to hasten uterine contractions during childbirth. For this reason, pregnant women should not use it.
The medicine has a distinct advantage over other antimalarials: although it is expensive and time consuming to produce, the parasites that cause malaria appear to be slow to develop a resistance to it. As a result, the drug is sometimes used to treat drug resistant malaria, in lieu of medications which may fail to work. Although it has been synthesized historically, researchers have yet to perfect an efficient and accurate synthesis process for the drug, so, for now, it continues to be produced in the traditional way, from cinchona bark.
Despite its historical usefulness, and potential for use in cases of drug resistance, quinine is not recommended by the World Health Organization (WHO) as a first-line treatment for malaria due to its side effects. A group of antimalarials called artemisins, originally isolated from the Artemisia plant, are favored as of 2012. Some people who use quinine can develop a dangerously low level of platelets in the blood, which affects the ability of the body to stem bleeding from cuts. The medicine can also be toxic to the liver and kidneys, and may also adversely affect the nerves of the body. Although levels in tonic water are not dangerous to health, some herbal remedies, such as those that aim to relieve muscle cramps, contain quinine in doses which could produce side effects.