Quinine is a medication used to treat malaria. Quinine was first isolated in 1820 from the bark of a cinchona tree. Bark extracts have been used to treat malaria since at least 1632. As of 2006, it is no longer recommended by the WHO (World Health Organization) as a first-line treatment for malaria, and it should be used only when artemisinins are not available. Quinine is also used to treat lupus and arthritis.

Quinine is a flavor component of tonic water and bitter lemon drink mixers. On the soda gun behind many bars, tonic water is designated by the letter "Q" representing quinine.

According to tradition, the bitter taste of anti-malarial quinine tonic led British colonials in India to mix it with gin, thus creating the gin and tonic cocktail, which is still popular today. Nowadays, the amount of quinine in tonic is much lower and drinking it against malaria is useless. In the US, quinine is listed as an ingredient in some Diet Snapple flavors, including Cranberry-Raspberry.

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