How should I initiate haloperidol (Haldol) intramuscular injection for acute agitation, including appropriate dosing, contraindications, and monitoring?

How to Initiate Haloperidol Intramuscular Injection

For acute agitation in adults, start with haloperidol 5-10 mg IM, which can be repeated every 30-60 minutes as needed, with a maximum daily dose of 40 mg. 1

Initial Dosing by Patient Population

Adults (Standard Dosing)

• Administer 5-10 mg IM for acute agitation 1
• Repeat the same dose every 30-60 minutes if partial or no response 1
• In severe agitation, doses may be repeated every 20-30 minutes until control is achieved 1
• Maximum daily dose: 40 mg 1
• Onset of action: 10-20 minutes IM, with peak effect at 60 minutes 1

Elderly or Frail Patients (≥65 years)

• Start with 0.5-1 mg IM 2, 3
• Low-dose haloperidol (≤0.5 mg) demonstrates similar efficacy to higher doses in older patients, with better outcomes including shorter length of stay and less restraint use 2
• For severe delirium in palliative care: 0.5-2 mg every 1 hour PRN until episode controlled 3
• Maximum recommended: 10 mg daily in frail or palliative patients 1

Pediatric Patients

• Dose: 0.05-0.15 mg/kg IM (maximum 5 mg per dose) 1, 4
• May be repeated hourly as needed 4
• Ages 12-16 years: initial dose 10 mg 1
• Ages 6-12 years: initial dose 2.5 mg (maximum daily 30 mg) 1

Critical Contraindications and Precautions

Absolute Contraindications

• Known QTc prolongation or conditions predisposing to arrhythmias 5
• Concurrent use with other QTc-prolonging agents 5
• Parkinson's disease or Lewy body dementia 5

Monitoring Requirements

• Monitor vital signs continuously, especially with repeated doses 1
• Watch for QTc prolongation risk, particularly above 7.5 mg/day 1
• Assess for extrapyramidal symptoms (EPS) after each dose 1
• Have respiratory support immediately available 5

Management Algorithm for Acute Agitation

Step 1: Initial Assessment

• Exclude medical causes of agitation (hypoxia, hypoglycemia, infection, substance withdrawal) 3
• Assess for contraindications to haloperidol 5
• Consider benzodiazepines as first-line for alcohol or substance-induced agitation 1

Step 2: First Dose Administration

• Adults: 5-10 mg IM 1
• Elderly: 0.5-1 mg IM 2
• Pediatric: 0.05-0.15 mg/kg IM (max 5 mg) 1, 4

Step 3: Response Assessment (30 minutes post-dose)

• If adequate response: Monitor and provide supportive care 1
• If partial response: Repeat same dose 1
• If no response: Repeat same dose and consider adding lorazepam 0.5-2 mg for refractory agitation 3

Step 4: Extrapyramidal Symptom Management

• If EPS develop: reduce next dose by 50% 1
• Consider prophylactic benztropine 1-2 mg IM if multiple doses needed 5
• Dystonic reactions require immediate treatment with diphenhydramine 50 mg IM or benztropine 2 mg IM 5

Combination Therapy Considerations

Haloperidol Plus Benzodiazepines

• For severe refractory agitation, combine haloperidol with lorazepam 0.5-2 mg 3
• This combination is effective but increases sedation and respiratory depression risk 5, 6
• Haloperidol 5 mg IM plus lorazepam 2 mg IM is a well-studied regimen 6
• Monitor respiratory status closely when combining agents 5

Common Pitfalls to Avoid

Dosing Errors

• Do not exceed 40 mg total daily dose 1
• Avoid escalating doses above 15 mg, as higher doses do not improve efficacy and increase adverse effects 1
• Do not use depot formulations (haloperidol decanoate) for acute agitation—these are only for maintenance therapy in stable patients 4

Safety Concerns

• Haloperidol has been rarely associated with cardiac arrhythmia and sudden death, particularly at higher doses 5
• The combination of IM olanzapine with benzodiazepines has been associated with fatalities and should be avoided 5
• Intramuscular haloperidol causes significant EPS in 20-30% of patients 3, 5

Monitoring Failures

• Failure to monitor for QTc prolongation with repeated dosing 1
• Not recognizing early EPS, leading to patient distress and non-compliance 1
• Inadequate respiratory monitoring when combining with benzodiazepines 5

Alternative Agents to Consider

While haloperidol remains effective, newer evidence suggests:

• IM ziprasidone (10-20 mg) and IM olanzapine (10 mg) show faster onset and fewer EPS than haloperidol 3, 7
• Both atypical agents demonstrated superior early efficacy (15-30 minutes) compared to haloperidol 7.5 mg IM 3, 7
• Oral risperidone 2 mg plus lorazepam 2 mg is non-inferior to IM haloperidol 5 mg plus lorazepam 2 mg 6