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
Jesuit's bark "Pulvis Patrum". The history of cinchona bark, which dates back more than 300 years, has greatly influenced that of pharmacy, botany, medicine, trade, theoretical and practical chemistry, and tropical agriculture. Circa 1650, the physician Sebastiano Bado declared that this bark had proved more precious to mankind than all the gold and silver that the Spaniards had obtained from South America, and the world confirmed his opinion. See also Swords, Ships and Sugar - The History of Nevis, by Vincent K. Hubbard, p. 73, where a large amount of "Peruvian Bark" had been captured by the pirate Basil Ringrose, also known