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
Bark painting from Stringybark ("Eucalyptus tetradonta"). The bark must be free of knots and other blemishes. It is best cut from the tree in the wet season when the sap is rising. Two horizontal slices and a single vertical slice are made into the tree, and the bark is carefully peeled off with the aid of a sharpened tool. Only the inner smooth bark is kept and placed in a fire. After heating in the fire, the bark is flattened under foot and weighted with stones or logs to dry flat. Once dry, it is ready to paint upon. Earth pigments—or ochres—in