What is the recommended dose of Haldol (haloperidol) administered intramuscularly (IM) for an agitated patient?

Haloperidol IM Dosing for Acute Agitation

For adult patients with acute agitation, administer haloperidol 5 mg IM as the initial dose, which can be repeated every 20-30 minutes as needed based on clinical response. 1

Initial Dosing Strategy

The standard starting dose is 5 mg IM for adults with moderate to severe agitation. 1, 2 This recommendation comes from the American College of Emergency Physicians and is supported by FDA labeling, which specifies 2-5 mg IM for prompt control of acutely agitated patients. 2

Key Dosing Parameters:

• Initial dose: 5 mg IM 1
• Onset of action: 20-30 minutes IM 3
• Peak effect: 30-60 minutes IM 3
• Repeat dosing interval: Every 20-30 minutes if inadequate response 1
• Alternative interval: Every 4-8 hours may be satisfactory for less severe cases 2

Dose-Response Considerations

There is a ceiling effect above 10-15 mg total dose—higher doses show diminishing returns and potentially decreased efficacy. 1 This is a critical pitfall to avoid, as clinicians may be tempted to escalate doses beyond this threshold without benefit.

Combination Therapy Options

For severe agitation or inadequate response to haloperidol alone, combine haloperidol 5 mg with lorazepam 2 mg IM, which produces faster sedation than monotherapy. 1, 4 These medications can be administered in the same syringe. 3

Alternative combinations include:

• Haloperidol + diphenhydramine (reduces extrapyramidal symptoms) 3
• Haloperidol + midazolam 3

Special Population Adjustments

For elderly or debilitated patients, start with lower doses (0.5-1 mg IM) as they are more susceptible to adverse effects. 2, 5 Recent research demonstrates that low-dose haloperidol (≤0.5 mg) in older adults (≥65 years) achieves similar efficacy to higher doses with better safety outcomes, including shorter length of stay and less restraint use. 5

Pediatric dosing (when applicable):

• Adolescents (13+ years): 2-5 mg IM 3
• Children (6-12 years): 0.5-2 mg IM 3
• Weight-based alternative: 0.1 mg/kg IM 3

Clinical Monitoring Algorithm

1. Evaluate response at 15-30 minutes after initial dose 1
2. If inadequate sedation: Administer additional 5 mg IM 1
3. Consider combination therapy if no response after 30 minutes 1
4. Monitor for extrapyramidal symptoms (occur in ~20% of patients) 1, 4
5. Watch for QTc prolongation, especially with repeated dosing 4

Comparative Efficacy Context

While haloperidol 5 mg IM is effective, droperidol 5 mg provides faster sedation with fewer repeat doses needed. 1 Additionally, recent comparative research shows that midazolam 5 mg IM achieves more effective sedation at 15 minutes than haloperidol, and olanzapine 10 mg IM provides superior sedation compared to haloperidol 5 mg or 10 mg. 6 However, haloperidol remains widely recommended due to its established safety profile and availability.

Critical Safety Considerations

Contraindications include:

• Intoxication states 3
• Respiratory compromise (use with caution) 3
• Anticholinergic delirium (may worsen condition) 3

Common adverse effects:

• Extrapyramidal symptoms (dystonia, akathisia) in ~20% 1, 4
• Orthostatic hypotension 3
• Cardiac dysrhythmias (rare but monitor QTc) 4

Transition to Oral Therapy

Switch to oral haloperidol within 12-24 hours after the last parenteral dose once the patient is stabilized. 2 Use the total 24-hour parenteral dose as an approximation for the initial oral daily dose, then adjust based on clinical response. 2