What is the starting dose of Haldol (haloperidol) for acute psychosis or agitation?

Starting Dose of Haloperidol for Acute Agitation

The recommended starting dose of haloperidol for acute agitation in adults is 5 mg intramuscularly, which can be combined with lorazepam 2-4 mg IM for superior efficacy. 1

Standard Dosing Protocol

Initial Dose

• Haloperidol 5 mg IM is the most extensively studied and effective starting dose for acute agitation and psychosis in adults 2, 1
• This dose produces significant reduction in agitation within 28-30 minutes on average 1
• The 5 mg dose has been consistently validated across multiple randomized trials as superior to lower doses (1-2 mg) 3

Combination Therapy (Preferred Approach)

• Adding lorazepam 2-4 mg IM to haloperidol 5 mg produces significantly greater agitation reduction than either drug alone 2, 1
• The combination achieves faster sedation (15-30 minutes vs 28 minutes for haloperidol alone) and requires fewer repeat doses 2, 1
• Alternative combination: haloperidol 10 mg with promethazine 25-50 mg produces more rapid tranquilization at 15,30,60, and 120 minutes compared to lorazepam 4 mg alone 2

Redosing Strategy

• If inadequate response, repeat dosing can occur at 30-minute to 1-hour intervals 1
• Maximum of 3-4 injections may be given in the initial control phase 3
• Efficacy shows dose-response relationship up to 10-15 mg; above this, there is diminished improvement 4

Route-Specific Dosing

Oral Administration (FDA-Approved)

For patients who can accept oral medication:

• Moderate symptoms: 0.5-2 mg twice or three times daily 5
• Severe symptoms: 3-5 mg twice or three times daily 5
• Oral haloperidol 15 mg daily has demonstrated efficacy for rapid tranquilization within 2 hours in severely agitated patients 6

Special Populations

• Geriatric or debilitated patients: 0.5-2 mg twice or three times daily (oral) 5
• First-episode psychosis: Start with 2 mg daily, as many patients respond to doses well below common usage levels 7

Critical Safety Considerations

Immediate Precautions

• Have diphenhydramine or benztropine immediately available for acute dystonic reactions (20% risk of extrapyramidal symptoms) 1, 4
• Monitor for QTc prolongation; avoid haloperidol if baseline QTc is prolonged 1
• Watch for neuroleptic malignant syndrome (hyperpyrexia, rigidity, altered mental status, autonomic instability) 1

Common Pitfalls to Avoid

• Do not escalate to large doses (>15-20 mg) during early treatment, as this results in excessive dosing and side effects without hastening recovery 1
• Do not use haloperidol monotherapy when combination with benzodiazepines is more effective for acute agitation 1
• Recognize that immediate effects are primarily sedation, not true antipsychotic response, which takes 4-6 weeks to properly assess 1
• Do not use haloperidol in anticholinergic or sympathomimetic toxicity, as it can exacerbate agitation due to anticholinergic side effects 2

Comparative Context

• Haloperidol 5 mg IM produces similar overall sedation to lorazepam 2 mg, though lorazepam acts more rapidly at 1-3 hours 2
• Midazolam 5 mg achieves faster sedation (18.3 minutes) compared to haloperidol 5 mg (28.3 minutes) 2, 1
• Atypical antipsychotics like ziprasidone 20 mg IM may be better tolerated with lower movement disorder rates, though haloperidol remains highly effective 2, 8