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 bread known from the 1890s, and in Finland "pettuleipä" (literally "pinewood-bark bread") was produced as ersatz bread during the Finnish Civil War of 1918. Finger sized twigs and branches were collected from deciduous trees and shrubs, and the bark split and the inner bark (the phloem and sometimes the vascular cambium) collected while still fresh. The yellow or green inner bark (depending on tree species) was dried over open fire, in an oven or dried in the sun for a few days. A mortar or mill was used to grind the bark to a fine powder to add to the flour.