What are the potential adverse reactions of Haldol (haloperidol)?

Haloperidol (Haldol) Adverse Reactions

Haloperidol commonly causes extrapyramidal symptoms (EPS), QT prolongation, and potentially irreversible tardive dyskinesia, with elderly patients and females at highest risk for severe adverse effects. 1

Neurological Adverse Effects

Extrapyramidal Symptoms (EPS)

• Acute dystonia: Involuntary muscle contractions affecting face, neck, back, and limb muscles 2

  • Typically occurs within first few doses or after dose increases
  • Can manifest as oculogyric crisis (eye deviation)
  • Laryngeal dystonia (rare but potentially life-threatening)
  • Higher risk in young patients, males, and with high-potency agents 2

• Parkinsonism: 2

  • Bradykinesia, tremors, and rigidity
  • More common at higher doses and in younger patients 3
  • May be difficult to differentiate from negative symptoms of schizophrenia

• Akathisia: 2

  • Subjective feeling of restlessness, physical agitation, pacing
  • Often misinterpreted as anxiety or psychotic agitation
  • Common reason for medication noncompliance
  • Responds better to beta-blockers or benzodiazepines than to anticholinergics 4

Tardive Dyskinesia

• Potentially irreversible involuntary movement disorder 1
• Characterized by rhythmical movements of tongue, face, mouth, or jaw
• Higher risk in:
  • Elderly patients
  • Females
  • Long-term therapy
  • Higher doses 1
• Early warning sign: fine vermicular tongue movements 2

Neuroleptic Malignant Syndrome (NMS)

• Rare but potentially fatal complication 1
• Characterized by hyperpyrexia, muscle rigidity, altered mental status
• Requires immediate discontinuation and supportive care 2

Cardiovascular Effects

• QT prolongation: Average 7ms prolongation 2

  • Less than other antipsychotics like thioridazine (25-30ms) or ziprasidone (5-22ms)
  • Risk increases with:
    • IV administration (not recommended route)
    • High doses
    • Combination with other QT-prolonging medications 2

• Orthostatic hypotension: Particularly in elderly patients 2

• Tachycardia 5

Other Adverse Effects

Endocrine and Metabolic

• Hyperprolactinemia: leading to gynecomastia, galactorrhea, menstrual irregularities 1
• Hyperglycemia or hypoglycemia
• Hyponatremia 1

Hematologic

• Mild and usually transient leukopenia or leukocytosis
• Rare agranulocytosis (usually with concurrent medications) 1

Gastrointestinal

• Constipation, nausea, vomiting
• Hypersalivation, dyspepsia, anorexia 1

Anticholinergic Effects

• Dry mouth, blurred vision
• Urinary retention
• May worsen delirium in patients with anticholinergic toxicity 4

Pregnancy Risks

• Neonatal extrapyramidal and/or withdrawal symptoms
• Potential risk of limb malformations when used with other teratogenic drugs 1

Risk Mitigation Strategies

1. Dose optimization:

   • Use lowest effective dose, especially in elderly (0.5mg or less) 4
   • Intramuscular route preferred over intravenous for parenteral administration 2

2. Management of EPS:

   • Anticholinergics (benztropine) for dystonia and parkinsonism 2
   • Beta-blockers or benzodiazepines for akathisia 2
   • Consider amantadine as alternative with fewer anticholinergic effects 4

3. Monitoring:

   • Regular assessment for tardive dyskinesia
   • ECG monitoring in patients with cardiac risk factors
   • Metabolic monitoring (glucose, electrolytes)
   • More frequent monitoring during initiation and dose adjustments 4

4. Special populations:

   • Avoid in elderly with dementia (increased mortality risk) 4
   • Use with extreme caution in pregnancy 1
   • Consider atypical antipsychotics as alternatives with lower EPS risk 2

Haloperidol remains useful in specific clinical scenarios, but its significant side effect profile requires careful patient selection, appropriate dosing, and vigilant monitoring for adverse effects.