مؤسسة الشرق الأوسط للنشر العلمي
عادةً ما يتم الرد في غضون خمس دقائق
Background: Serotonin syndrome is a potentially life-threatening toxidrome resulting from increased serotonergic activity in the central nervous system. It is most often associated with initiation or escalation of serotonergic drugs, yet removal of a serotonin antagonist may similarly destabilize receptor balance. Case Presentation: A 54-year-old man with familial adenomatous polyposis and colon cancer underwent multiple abdominal surgeries for recurrent desmoid tumors and was admitted with small bowel obstruction complicated by short gut syndrome and a complex symptom burden. Palliative care managed pain and nausea with opioids, duloxetine, ondansetron, gabapentin, and olanzapine. After tapering olanzapine, he developed progressive myoclonus and tremors. Serotonin syndrome was suspected, given serotonergic polypharmacy and withdrawal of a 5-HT₂A antagonist. Discontinuing duloxetine and ondansetron, reducing the opioid dose, and reinitiating olanzapine led to rapid symptom resolution, with no alternative diagnosis identified. Discussion: This case illustrates a less recognized mechanism of serotonin syndrome: the unmasking of serotonergic toxicity after discontinuation of olanzapine, a 5-HT₂A receptor antagonist, in a patient already exposed to several serotonergic medications. At the receptor level, withdrawal of 5-HT₂A blockade may enhance serotonin signaling through unblocked receptor subtypes, tipping a previously compensated serotonergic system into toxicity. Conclusion: In complex inpatients with polypharmacy, clinicians should consider serotonin syndrome not only after initiating or up-titrating serotonergic medications but also after discontinuing agents that may have provided functional protection against serotonergic excess, such as atypical antipsychotics with strong 5-HT₂A antagonism.