Quinine is a white crystalline alkaloid derived from (and first isolated from in 1820) the bark of the cinchona tree from South America, long used in treating a variety of ailments. It was preeminent in early treatment of malaria until the 1930s when atabrine, a synthetic alkaloid drug, was introduced; after this more suitable quinine derivatives such as chloroquine were synthesized. Quinine is also a mild analgesic and may prevent cramps and suppress heart rhythm (see arrhythmias) disorders. Now rarely used, its side effects include vomiting, deafness, vertigo, and vision disturbance.