What is "cinchonism"

Cinchonism \Cin"cho*nism\, n. [From Cinchona.] (Med.) A condition produced by the excessive or long-continued use of quinine, and marked by deafness, roaring in the ears, vertigo, etc.

n. A pathological condition in humans caused by an overdose of quinine or its natural source, cinchona bark.

Cinchonism or quinism is a pathological condition caused by an overdose of quinidine or its natural source, cinchona bark. Quinine is medically used to treat malaria. In much smaller amounts, quinine is an ingredient of tonic drinks, acting as a bittering agent. Cinchonism can occur from therapeutic doses of quinine, either from one or several large doses. Quinidine (Class 1A anti-arrhythmic) can also cause cinchonism symptoms to develop with as little as a single dose.