Cinchonism or quinism
is a pathological condition in humans caused by an overdose of quinine 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
or from small doses over a longer period of time
not from the amounts used in tonic drinks
but possibly from ingestion of tonic water as a beverage over a lengthy period of time
Quinidine (Class 1A anti-arrhythmic) can also cause cinchonism
Symptoms of mild cinchonism
which may occur from standard therapeutic doses of quinine
include flushed and sweaty skin, ringing of the ears (tinnitus) , blurred vision, impaired hearing, confusion, reversible high-frequency hearing loss, headache, abdominal pain, rashes, lichenoid photosensitivity , vertigo, dizziness, dysphoria, nausea and vomiting, and diarrhea.
]Large doses of quinine may lead to severe symptoms of cinchonism ]
skin rashes, deafness (reversible), somnolence, diminished visual acuity or blindness ,anaphylactic shock, and disturbances in cardiac rhythm or conduction, death from cardiotoxicity
Quinine overdose can also result in a rare form of hypersensitivity reaction termed blackwater fever that results in massive hemolysis, hemoglobinemia, hemoglobinuria, and renal failure.[citation needed
Patients treated with quinine may also suffer from hypoglycemia (especially if administered intravenously) and hypotension (low blood pressure).
Most symptoms of cinchonism (except in severe cases) are reversible and disappear once quinine is withdrawn.