Severe serotonin syndrome due to high-dose venlafaxine: A rare case successfully managed with chlorpromazine

OpenAlex · English

Serotonin syndrome is a potentially life-threatening clinical condition caused by excessive serotonergic activity within the central nervous system. In this report, we present the case of a 40-year-old woman with a diagnosis of major depressive disorder who developed serotonin syndrome following a suicidal ingestion of 3000 mg extended-release venlafaxine. The patient manifested agitation, clonus, generalized tonic–clonic seizures, and altered mental status. Despite intensive supportive care and administration of oral cyproheptadine, no clinical improvement was achieved. However, following intramuscular administration of 25 mg chlorpromazine, the patient demonstrated rapid neurological and hemodynamic recovery. This case highlights that severe serotonin syndrome may occur after ingestion of a single serotonergic agent at high doses, and that chlorpromazine may provide therapeutic benefit in cases where conventional treatments fail.