Selective serotonin reuptake inhibitor toxicity


  • Most serious adverse effect is potential to produce serotonin syndrome
    • However, serotonin syndrome unlikely to occur unless co-ingested with other serotonergic drug classes (MAOIs, SNRI, TCAs, amphetamines, opiates)
  • Pure overdoses are generally benign (mortality uncommon). Associated with less toxicity than tricyclic antidepressants.
  • Are the most commonly prescribed antidepressants in the United States[1]
  • Examples include fluoxetine (Prozac), paroxetine (Paxil), fluvoxamine (Luvox), sertraline (Zoloft), escitalopram (Lexapro), and citalopram (Celexa)
  • Citalopram (>600 mg) and escitalopram (>300mg) are unique, as they may cause dose dependent QT prolongation and increase risk of torsades de pointes

Clinical Features

Differential Diagnosis

Anticholinergic toxicity Causes





  • Treatment is mostly supportive. Consult poison control for guidance, if needed.
  • Administer activated charcoal if lethal amount ingested within 1-2 hours
  • Continuous cardiac monitoring required for citalopram (>600 mg) and escitalopram (>300mg) for at least 8 hours.
    • If citalopram (>1000 mg) and escitalopram (>500 mg) has been ingested then monitor for 12-24 hours
  • Manage seizures with benzodiazepines
  • Manage hyperthermia
  • If suspecting Serotonin Syndrome, stop all serotonergic medication:
    • SSRIs
    • Anticonvulsants (valproate)
    • Antiemetics (ondansetron, metoclopramide)
    • Analgesics (fentanyl, tramadol, methadone)
    • Antibiotics (linezolid)


  • Consider admission for patients who are tachycardic or lethargic 6hr after ingestion
  • ECG before clearing a patient with citalopram ingestion

See Also

External Links


  1. Pirraglia PA, Stafford RS, Singer DE. Trends in Prescribing of Selective Serotonin Reuptake Inhibitors and Other Newer Antidepressant Agents in Adult Primary Care. Prim Care Companion J Clin Psychiatry. 2003 Aug;5(4):153-157. doi: 10.4088/pcc.v05n0402. PMID: 15213776; PMCID: PMC419384.
  2. Dawson AH, Buckley NA. Pharmacological management of anticholinergic delirium – theory, evidence and practice. Br J Clin Pharmacol. 2015;81(3):516-24.