Quinine side effects include deafness, low blood platelets, and an irregular heartbeat. Use can make one more prone to sunburn. While it is unclear if use during pregnancy causes harm to the baby, use to treat malaria during pregnancy is still recommended. Quinine is an alkaloid, a naturally occurring chemical compound. How it works as a medicine is not entirely clear. 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. It is on the World Health Organization's List of Essential Medicines, the most effective and
Cinchona South America, the species had geographically distinct distributions. The introduction of several species into cultivation in the same areas in India and Java, respectively, by the English and Dutch East India Companies led to the formation of hybrids. Linnaeus described the genus based on the species "Cinchona officinalis." Nearly 300 species have been described and named in the genus but a revision of the genus in 1998 identified 23 distinct species. The febrifugal properties of bark from trees now known to be in the genus "Cinchona" were used by many South American cultures but malaria was an Old World disease