Quinine toxicity

Quinine commonly causes cinchonism (gastrointestinal distress, headache, vertigo, blurred vision, and tinnitus). Severe overdose results in disturbances in cardiac conduction that resemble quinidine toxicity. Hematotoxic effects occur, including hemolysis in glucose-6-phosphate dehydrogenase (G6PD)-deficient patients. Blackwater fever (intravascular hemolysis) is a rare and sometimes fatal complication in quinine-sensitized persons. Quinine is contraindicated in pregnancy.Drug interactions include potentiation of neuromuscular-blocking agents and elevation of digoxin levels if taken concurrently with quinine.