• Haloperidol
  • Olanzapine
  • Ziprasidone


  • Mechanism of Action: Antipsychotic; blocks dopaminergic receptors in the brain, depressing reticular activating system.
  • Indications: Acute agitation, psychosis
  • Contraindications: Allergy to drug, Parkinson’s disease. Caution in QT prolongation.
  • Dosage: 5-10 mg PO/IM/IV q2hrs (Max 100mg/day)
  • Onset: 10-20 minutes
  • Duration: 4-6 hours (IV)
  • Adverse Reactions: Drowsiness, extrapyramidal symptoms, tardive dyskinesia
  • Special Considerations: May increase liver function test values
Video Credit: Nurse Ryan

*Deep Dive: Understanding Haloperidol (EP Monthly)


  • Mechanism of Action: Atypical antipsychotic; binds to dopamine, histamine, alpha1, and 5HT2 receptors. 
  • Indications: Acute agitation, schizophrenia, bipolar disorder
  • Contraindications: Allergy to drug/class. Should not be given for dementia-related psychosis, NMS
  • Dosage: 5-10 mg IM/ODT (max 30mg/day)
  • Onset: 15-45 minutes
  • Duration: Half life of 30 hours for most adults
  • Adverse Reactions: Orthostatic hypotension (3-20%), Neuroleptic malignant syndrome, extrapyramidal side effects
  • Special Considerations: N/A
Video Credit: Nurse Ryan

*Deep Dive: Adverse Events from IV Olanzapine for Agitation in the ED (ALiEM)


  • Mechanism of Action: Antipsychotic; D2 and 5HT2 antagonist. Strong alpha 1 blocker and histamine-1 antagonist.
  • Indications: Acute agitation, psychosis.
  • Contraindications: QT prolongation, allergy to drug, decompensated heart failure
  • Dosage: 10-20mg IM q2-4 hrs (Max: 40 mg/day)
  • Onset
  • Duration: Half life 2-7 hrs.
  • Adverse Reactions: Prolonged QT, torsades, neuroleptic malignant syndrome, extrapyramidal side effects, dizziness
  • Special Considerations: None 
Video Credit: Eric Christianson

*Deep Dive: Comparison of IM Midazolam, Olanzapine, Ziprasidone, and Haloperidol for Behavioral Control (REBEL EM)

Brandon Simpson, PA-C
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