We report a case of delayed recovery from general anesthesia following a routine parathyroidectomy. Our objectives are to describe the process of establishing a differential diagnosis and subsequent management of a patient presenting with atypical neurological signs from an unknown etiology and to increase awareness about the potential for serotonin syndrome and neurotoxicity due to known interactions between methylene blue and selective serotonin-noradrenaline re-uptake inhibitors. ICU management of Serotonin Toxicity is briefly described.