Serotonin syndrome: a rare undiagnosed cause of hyperpyrexia

Abstract Serotonin syndrome (SS) is a rare but potentially life-threatening condition, and it caused by increasing serotonergic activities. It an underdiagnosed under-reported condition. Clinical manifestations can range from mild to moderate severe symptoms. The intensity of symptoms reflects the degree serotonin toxicity, easily overlooked physicians. Severe toxicity typically occurs combination agents. Herein, we describe case in 38-year-old Egyptian male with history generalized anxiety disorder depression. With increased depressive symptoms, he received 20 mg fluoxetine daily, developed 1 month after starting fluoxetine, which uncommon onset presentation. patient was already on tramadol for chronic low backache. aim increase awareness among physicians neuropsychiatrists.