Lesson of the month 2: An easily missed cause of confusion.

We describe the case of an 85-year-old woman who developed acute confusion, acute kidney injury and temperature spikes while on extended courses of beta-lactams for osteomyelitis. The cause of her deterioration was felt to be due to sepsis when in fact it was as a result of toxicity from antibiotics. This was demonstrated by a rapid resolution in her condition following haemodialysis. We also performed a literature review to appraise the neuro and nephrotoxicity of various antibiotics and how best to manage toxicity when it occurs. © Royal College of Physicians 2016. All rights reserved.