What are the major side effects of Haloperidol (antipsychotic) and how to treat them?

Major Side Effects of Haloperidol and Their Management

Haloperidol commonly causes extrapyramidal symptoms (EPS) as its primary side effect, which should be managed by dose reduction or switching to an atypical antipsychotic rather than adding anticholinergic medications. 1

Common Side Effects and Their Management

1. Extrapyramidal Symptoms (EPS)

• Acute dystonia: Involuntary muscle contractions, often affecting the face, neck, and back

  • Occurs in 10-20% of patients, typically within first 48 hours
  • Management:
    • Immediate treatment with diphenhydramine 25-50mg IV/IM or benzodiazepines 1
    • Reduce haloperidol dose or switch to atypical antipsychotic 1

• Akathisia: Inner restlessness and inability to sit still

  • Management:
    • Dose reduction
    • Beta-blockers (propranolol 10-30mg TID)
    • Low-dose benzodiazepines (lorazepam 0.5-1mg) 2

• Parkinsonism: Tremor, rigidity, bradykinesia

  • Management:
    • Dose reduction is first-line approach
    • Avoid in patients with Parkinson's disease or Lewy body dementia 1

• Tardive dyskinesia: Late-onset involuntary movements

  • Risk increases with duration of treatment (50% risk after 2 years in elderly) 1
  • Management:
    • Prevention is key - use lowest effective dose for shortest time
    • Consider switching to atypical antipsychotic
    • May be irreversible once established

2. Cardiovascular Effects

• QT prolongation and risk of torsades de pointes

  • Management:
    • Baseline ECG before starting treatment
    • Regular ECG monitoring during treatment
    • Avoid combining with other QT-prolonging medications 1
    • Discontinue if QTc >500ms

• Orthostatic hypotension

  • Management:
    • Start with lower doses in elderly/frail patients (0.25-0.5mg) 1
    • Advise patients to change positions slowly

3. Anticholinergic Effects

• Dry mouth, blurred vision, urinary retention, constipation
• Management:
  • Adequate hydration
  • Regular monitoring for urinary retention in elderly
  • Stool softeners for constipation

4. Neuroleptic Malignant Syndrome (NMS)

• Rare but potentially fatal: hyperthermia, muscle rigidity, autonomic instability
• Management:
  • Immediate discontinuation of haloperidol
  • ICU admission for supportive care
  • Consider dantrolene or bromocriptine 1

5. Endocrine Effects

• Hyperprolactinemia leading to galactorrhea, amenorrhea, gynecomastia
• Management:
  • Consider dose reduction or switching to prolactin-sparing antipsychotic

Special Populations

Elderly Patients

• Higher sensitivity to side effects
• Start with lower doses (0.25-0.5mg) 1
• Monitor closely for sedation, falls, and cognitive impairment

Pregnant Women

• Use only if benefit justifies risk
• Risk of neonatal EPS and withdrawal symptoms if used in third trimester 3
• No confirmed teratogenic effects but caution advised

Algorithmic Approach to Managing Side Effects

1. For mild EPS:

   • Reduce dose by 25-50%
   • If symptoms persist, consider switching to atypical antipsychotic

2. For moderate-severe EPS:

   • For acute dystonia: Immediate treatment with diphenhydramine 25-50mg IV/IM
   • For akathisia: Add propranolol 10mg TID or lorazepam 0.5mg BID
   • Consider switching to atypical antipsychotic (olanzapine, quetiapine)

3. For QT prolongation:

   • If QTc >450ms but <500ms: Reduce dose and monitor more frequently
   • If QTc >500ms: Discontinue haloperidol and switch to alternative

4. For NMS:

   • Immediate discontinuation
   • ICU admission
   • Supportive care and specific treatments (dantrolene/bromocriptine)

Common Pitfalls to Avoid

1. Adding anticholinergic medications (benztropine, trihexyphenidyl) for EPS management

   • These can worsen cognitive function and cause additional anticholinergic side effects
   • Better to reduce dose or switch medications 1

2. Failure to monitor for tardive dyskinesia

   • Regular assessment needed, especially in long-term use
   • Risk increases with duration of treatment

3. Combining with other dopamine antagonists

   • Increases risk of EPS and tardive dyskinesia

4. Abrupt discontinuation

   • Can lead to withdrawal dyskinesia or rebound psychosis
   • Taper gradually when discontinuing

5. Overlooking drug interactions

   • Haloperidol is metabolized by CYP3A4 and CYP2D6
   • Interactions with carbamazepine, phenytoin, rifampicin can significantly affect levels 4

By understanding these side effects and their management strategies, clinicians can optimize the safety and efficacy of haloperidol treatment while minimizing adverse outcomes that impact morbidity, mortality, and quality of life.