Quinine Quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to "Plasmodium falciparum" that is resistant to chloroquine when artesunate is not available. While used for restless legs syndrome, it is not recommended for this purpose due to the risk of side effects. It can be taken by mouth or used intravenously. Malaria resistance to quinine occurs in certain areas of the world. Quinine is also the ingredient in tonic water that gives it its bitter taste. Common side effects include headache, ringing in the ears, trouble seeing, and sweating. More severe
Tonic (physiology) Tonic (physiology) Tonic in physiology refers to a physiological response which is slow and may be graded. This term is typically used in opposition to a fast response. For instance, tonic muscles are contrasted by the more typical and much faster twitch muscles, while tonic sensory nerve endings are contrasted to the much faster phasic sensory nerve endings. Tonic muscles are much slower than twitch fibers in terms of time from stimulus to full activation, time to full relaxation upon cessation of stimuli, and maximal shortening velocity. These muscles are rarely found in mammals (only in the muscles moving the