Acute confusion and blindness from quinine toxicity

Abstract

Quinine is widely used for nocturnal leg cramps, despite limited evidence of its clinical efficacy in this condition. Accidental overdose is associated with serious ocular complications and can potentially be fatal. We report the case of a 57-year-old man who presented with acute confusion and bilateral blindness after consuming approximately 7.2 g quinine sulphate along with an unknown quantity of alcohol. He was treated with general supportive measures and nitrates, with an apparent initial recovery, but visual field defects persisted. This case highlights the potential toxic effects of quinine, the dangers of its bulk prescription, and the lack of strict guidelines with regard to its prescription. We suggest that restricted prescribing for leg cramps, better patient education about the toxic nature of the drug, and clear labelling of this hazard on the dispensing bottles might lead to a reduction in the cases of quinine poisoning.