cinchonism

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.

Signs and symptoms

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 [1], 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Most symptoms of cinchonism (except in severe cases) are reversible and disappear once quinine is withdrawn.

External links

• IPCS INTOX databank entry for quinine
• Side effect of quinine for nocturnal cramps - letter printed in the British Medical Journal with a photograph of hands affected by lichenoid photosensitivity
• Effects of Quinine on the Excitability and Voltage-Dependent Currents of Isolated Spiral Ganglion Neurons in Culture