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

Adverse Effects of Haloperidol (Haldol)

Haloperidol can cause significant neurological, cardiovascular, and metabolic adverse effects, with extrapyramidal symptoms being the most common and concerning side effects requiring monitoring and management. 1, 2

Neurological Side Effects

Extrapyramidal Symptoms (EPS)

• Acute dystonia: Involuntary muscle contractions typically occurring within the first few doses or after dose increases

  • Higher risk in young patients, males, and with high-potency agents 1
  • Presents as muscle spasms usually involving the face, extremities, and trunk 3
  • Management: Anticholinergics like benztropine (1-2 mg daily, max 6 mg) 1

• Parkinsonism: Bradykinesia, tremors, and rigidity

  • More common at higher doses and in younger patients 1
  • May be difficult to differentiate from negative symptoms of schizophrenia
  • Management: Anticholinergics or amantadine (fewer anticholinergic effects) 1

• Akathisia: Subjective feeling of restlessness, physical agitation, and pacing

  • Responds better to beta-blockers (propranolol, metoprolol) or benzodiazepines than to anticholinergics 1

• Tardive dyskinesia: Potentially irreversible involuntary movements

  • Higher risk in elderly patients, females, and with long-term therapy 2
  • Characterized by rhythmical involuntary movements of tongue, face, mouth, or jaw
  • No known effective treatment; discontinuation of haloperidol recommended if symptoms appear 2

• Neuroleptic malignant syndrome (NMS): Rare but potentially fatal

  • Presents with hyperpyrexia, muscle rigidity, altered mental status, and autonomic instability 2

Cardiovascular Side Effects

• QT prolongation: Haloperidol causes an average 7ms QT prolongation 1

  • Risk increases with:
    • IV administration (FDA non-black box warning due to deaths with high doses) 3
    • High doses
    • Combination with other QT-prolonging medications
  • Can potentially lead to torsades de pointes and sudden cardiac death 3
  • Intramuscular route preferred over intravenous for parenteral administration 3

• Orthostatic hypotension: Particularly concerning in elderly patients 1

Other Significant Side Effects

Endocrine and Metabolic Effects

• Lactation and breast engorgement
• Menstrual irregularities
• Gynecomastia
• Impotence or increased libido
• Hyperglycemia, hypoglycemia, and hyponatremia 2

Hematologic Effects

• Mild and usually transient leukopenia and leukocytosis
• Minimal decreases in red blood cell counts
• Anemia
• Rare agranulocytosis (usually in association with other medications) 2

Hepatic Effects

• Impaired liver function
• Jaundice 2

Gastrointestinal Effects

• Anorexia
• Constipation
• Diarrhea
• Hypersalivation
• Dyspepsia
• Nausea and vomiting 2

Autonomic Effects

• Dry mouth
• Blurred vision
• Urinary retention
• Diaphoresis
• Priapism 2

Other CNS Effects

• Insomnia, restlessness, anxiety
• Euphoria, agitation, drowsiness
• Depression, lethargy, headache
• Confusion, vertigo
• Grand mal seizures
• Exacerbation of psychotic symptoms 2

Monitoring Recommendations

1. Regular assessment for tardive dyskinesia
2. ECG monitoring in patients with cardiac risk factors
   • Consider monitoring when using doses >5 mg 4
   • Telemetry only for high-risk patients receiving cumulative doses ≥100 mg or with QTc >500 ms 4
3. Metabolic monitoring
   • More frequent monitoring during initiation and dose adjustments 1

Special Considerations

• Elderly patients: Higher risk of developing tardive dyskinesia (12-month incidence of 12.3%) 1

  • FDA warns of increased risk of death in older adults with dementia treated with antipsychotics 1
  • Use lowest effective dose if necessary 1

• Withdrawal: Gradual discontinuation recommended to reduce withdrawal emergent neurological signs 2

• Antipsychotic selection: Consider atypical antipsychotics as alternatives with lower EPS risk, especially in special populations such as the elderly and pregnant women 1

By understanding these adverse effects and implementing appropriate monitoring strategies, clinicians can better manage the risks associated with haloperidol treatment while maximizing its therapeutic benefits.