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 of the long list of brochures defending its use and the only independent article on this bark which has been issued by a Jesuit. The two Genoese, Girolamo Bardi, a priest, and Sebastiano Baldo, a physician, who were among the pioneer advocates of the plant, were intimate with the cardinal, and Baldo prefixed to his principal work a letter from de Lugo, dated 1659, on cinchona, which shows that the cardinal even when seventy-seven years old was still active in its behalf. Circumstances created a suitable opportunity for disseminating the bark from Rome throughout Europe by means of the Jesuits.