Olanzapine overdose mimicking opioid intoxication

Ann Emerg Med. 1999 Aug;34(2):279-81. doi: 10.1016/s0196-0644(99)70249-0.


We report significant central nervous system depression and the previously unreported phenomenon of pupillary constriction after acute overdose of olanzapine (Zyprexa) in 4 patients. Phase 2 trials describe a typically benign course in overdose, and published abstracts note a wide spectrum of clinical effects with supratherapeutic ingestion of olanzapine. Our patients demonstrated profound central nervous system depression, and 2 required advanced airway support. All 4 patients recovered with supportive care. Olanzapine should be added to opioid and alpha(2)-adrenergic agonist intoxication in the differential diagnosis of the patient with depressed mental status and miosis.

MeSH terms

  • Adult
  • Antipsychotic Agents / poisoning*
  • Benzodiazepines
  • Central Nervous System / drug effects*
  • Central Nervous System Depressants / poisoning*
  • Drug Overdose
  • Female
  • Humans
  • Male
  • Middle Aged
  • Miosis
  • Narcotics / poisoning*
  • Olanzapine
  • Pirenzepine / analogs & derivatives*
  • Pirenzepine / poisoning
  • Pupil / drug effects


  • Antipsychotic Agents
  • Central Nervous System Depressants
  • Narcotics
  • Benzodiazepines
  • Pirenzepine
  • Olanzapine