We describe a case of a 44-year-old woman with a borderline personality disorder and chronic gamma- butyrolactone (GBL) use who presented with progressive dyspnoea and an altered mental status. A high anion gap metabolic acidosis and acute lung injury was diagnosed. We hypothesise this was caused by GBL. In this case report we describe the diagnostic process and possible pathophysiological mechanisms that may have led to this life-threatening condition.