Quinine Sulfate (Qualaquin) is an anti-malarial medication used for treating malaria. Quinine is an alkaloid derived from the bark of the cinchona tree, has long been used for medicinal purposes. In the 19th century, quinine gained popularity as an effective treatment for malaria. Malaria is common in areas such as Africa, South America, and Southern Asia. Quinine Sulfate is a FDA-approved medicine for use only in treating malaria. Some people have used Quinine Sulfate to treat leg cramps, but this is not an FDA-approved use. Prolonged administration of quinine may produce toxic symptoms such as deafness, disturbances in vision, rash, and gastrointestinal symptoms.