We describe an elderly gentleman with end stage renal disease on haemodialysis who presented with ophthalmic zoster infection and was discharged on oral acyclovir. He presented again a few days later with confusion and expressive dysphasia. Differential diagnosis was mainly between varicella-zoster virus (VZV) associated encephalitis versus acyclovir toxicity. Cerebrospinal fluid analysis confirmed the diagnosis of VZV associated encephalitis and the patient was treated with intravenous acyclovir and steroids with full recovery back to pre-admission neurological status.