A 55-year-old woman presented to the emergency department following an episode of severe visual impairment, headache, dizziness and confusion. The patient had been taking quinine sulfate as long-term medication for leg cramps. During an episode of sleepwalking, the patient had taken an overdose of quinine sulfate. Following a thorough investigation and assessment, a diagnosis of ocular quinine toxicity was made. We present this case and highlight the risks of quinine prescription.