Cinchonism

Cinchonism or quinism is poisoning from an overdose of cinchona alkaloids. Cinchona bark is the source of quinine and quindine. Quinine is used to treat malaria. In small amounts it is used in tonic water to give a bitter flavor. Cinchoism can be caused by medical doses of quinine or quindine.
Signs and symptoms.
Symptoms of mild cinchonism can include:
Large doses of quinine can cause: 
People treated with quinine may also suffer from low blood sugar and hypotension (low blood pressure).
Most symptoms of cinchonism (except in severe cases) are reversible and disappear once quinine is withdrawn.