“…Our patient had sinus tachycardia, and responded to esmolol hydrochloride infusion quickly. Serotonin syndrome on the other hand is a drug related toxic condition caused by serotonergic agents as a result of increased serotonin activity in the brain (3). It is characterized with a triad of neuromuscular hyperactivity (hyperreflexia, myoclonus, coordination disorder, tremor), autonomous disorders (hyperhidrosis, hyperthermia, diarrhea, hyper/hypotension, nausea-vomiting) and changes in consciousness (confusion, hypomania, agitation) (3).…”