The drug quinine was taken off the market in the United States in 2006 due to safety concerns. The Food and Drug Administration (FDA) determined that quinine was not effective for treating most conditions and had a high risk of serious side effects. Quinine was originally used to treat malaria, but it is no longer recommended for this purpose due to its potential to cause serious problems such as heart rhythm disturbances, allergic reactions, and kidney damage. Quinine is still available in other countries and is used off-label to treat leg cramps, but it should be used with caution.