Quinine associated blindness

Quinine is commonly prescribed to the elderly for the treatment of benign nocturnal cramps, yet its use is not without complications.

This article presents a case of quinine toxicity producing bilateral blindness, followed by a review of the adverse reactions associated with quinine use and its efficacy in treating benign nocturnal muscular cramps.

Visual loss has been associated with quinine serum concentrations above 10 microg/mL (therapeutic range 2-5 microg/mL). Other adverse reactions include neurological symptoms, haemolysis, acute renal failure and arrhythmia. There is conflicting evidence for the efficacy of quinine for leg cramps in randomised controlled studies, however, meta-analysis of these studies suggests some benefit. Although severe side effects are rare at therapeutic doses, the possibility of overdose needs to be considered when prescribing and an individual risk benefit analysis needs to be made. Benefits and adverse reactions should be closely monitored and medication ceased if appropriate.