Haloperidol IM Dosing
For acute agitation in adults, administer haloperidol 5 mg IM as the initial dose, which can be repeated every 20-30 minutes as needed, with a ceiling effect at 10-15 mg total dose beyond which efficacy diminishes. 1, 2, 3
Standard Adult Dosing Algorithm
Initial dose: 5 mg IM for acute agitation 1, 2, 3
Repeat dosing strategy:
- Evaluate response at 15-30 minutes 2
- If inadequate sedation, administer additional 5 mg IM 2
- May repeat every 20-30 minutes until tranquilization achieved 2, 3
- Critical ceiling effect: Maximum benefit occurs at 10-15 mg total dose—higher doses show diminishing returns and potentially decreased efficacy 1, 2
- Maximum daily limit: 40 mg 3
FDA-approved dosing: The official label recommends 2-5 mg IM for prompt control of acutely agitated patients, with subsequent doses as often as every hour, though 4-8 hour intervals may be satisfactory 4. However, the more recent guideline evidence supports the 5 mg starting dose as optimal for most acute situations 1, 2.
Combination Therapy for Severe Agitation
If monotherapy inadequate after 30 minutes, consider combination approaches: 2
- Haloperidol 5 mg + lorazepam 2 mg IM: Produces faster sedation than monotherapy 1, 2
- Haloperidol + diphenhydramine: Reduces extrapyramidal symptoms 2
- Haloperidol + midazolam: Alternative combination option 2
Special Population Dosing
Geriatric patients (≥65 years):
- Start with 0.5-1 mg IM 5
- Low-dose haloperidol (≤0.5 mg) demonstrates similar efficacy to higher doses in older adults with significantly better safety profile 5
- Higher doses in elderly patients increase sedation risk without improving agitation control 6
- Adolescents (13+ years): 2-5 mg IM, may repeat every 20-30 minutes 7, 2
- Children (6-12 years): 0.5-2 mg IM 7, 2
- Weight-based alternative: 0.1 mg/kg IM (maximum 5 mg per dose) 3
- Maximum daily dose for pediatrics: 30 mg 3
Critical Safety Monitoring
Absolute contraindications: 2
Use with extreme caution in: 2
- Respiratory compromise 2
Monitor for adverse effects:
- Extrapyramidal symptoms (dystonia, akathisia): Occur in ~20% of patients, more common at higher cumulative doses and in young males 2, 3
- QTc prolongation: Increased risk above 7.5 mg/day, monitor with repeated dosing 2, 3
- Orthostatic hypotension: Particularly in unstable patients 2, 3
- Respiratory depression: When combined with benzodiazepines 3
Common Pitfalls to Avoid
Overdosing trap: Despite guidelines recommending lower doses, clinicians frequently administer higher than recommended initial doses (>1 mg in elderly, >5 mg in adults), which increases adverse effects without improving efficacy 6. The evidence shows no benefit to exceeding 10-15 mg total dose 1, 2.
First-episode psychosis: Many patients respond to doses as low as 2 mg daily, with optimal doses well below common practice levels 8. Starting too high compromises future medication adherence due to extrapyramidal side effects 1.
Geriatric population: The recommended 0.5 mg starting dose is frequently ignored, with 37.5% of elderly patients receiving >1 mg initially in one study, resulting in higher sedation rates without improved outcomes 6.