What is promethazine used for?

Promethazine Uses and Applications

Promethazine is primarily used for prevention and control of nausea and vomiting, allergic conditions, motion sickness, and as a sedative, though it carries significant safety concerns including anticholinergic effects, sedation, and respiratory depression risks. 1

Primary Indications

• Antiemetic Uses:

  • Prevention and control of nausea and vomiting associated with certain types of anesthesia and surgery 1
  • Antiemetic therapy in postoperative patients 1, 2
  • Active and prophylactic treatment of motion sickness 1

• Allergy Management:

  • Perennial and seasonal allergic rhinitis 1
  • Vasomotor rhinitis 1
  • Allergic conjunctivitis due to inhalant allergens and foods 1
  • Mild, uncomplicated allergic skin manifestations (urticaria and angioedema) 1
  • Amelioration of allergic reactions to blood or plasma 1
  • Dermographism 1
  • Adjunctive therapy for anaphylactic reactions after acute manifestations are controlled 1

• Sedation:

  • Preoperative, postoperative, and obstetric sedation 1
  • Adjunctive therapy to analgesics for control of postoperative pain 1
  • Relief of apprehension and production of light sleep 1

Dosing Considerations

• Standard adult dosing: 12.5 to 25 mg every 4-6 hours 3
• Elderly patients: Start with lower doses (6.25 mg) due to increased sensitivity to anticholinergic effects 3, 4
• Research shows: Low-dose promethazine (6.25 mg) is as effective as higher doses (12.5 mg) with fewer adverse effects 4, 5

Safety Concerns and Precautions

• FDA black box warning: Injectable forms carry risk of serious tissue injury with incorrect administration 6, 7
• Respiratory risks: Associated with respiratory depression, especially when combined with opioids 3
• Anticholinergic effects: Dry mouth, urinary retention, blurred vision, and cognitive impairment 3
• Sedation: Causes drowsiness, which may impair driving and operation of machinery 3
• Cardiovascular effects: Can cause hypotension, especially with rapid IV administration 3
• Extrapyramidal symptoms: May cause dystonic reactions 3

Special Population Considerations

• Elderly patients: The American Geriatrics Society explicitly cautions against use in elderly patients due to high anticholinergic burden and fall risk 3
• Children: Contraindicated in children under 2 years due to risk of fatal respiratory depression 3
• Respiratory conditions: Use with caution; alternative antiemetics may be preferred 3

Alternative Antiemetics to Consider

• 5-HT3 antagonists: Ondansetron has been shown to be equally effective with fewer side effects 8, 7
• Other options for nausea/vomiting:
  • Prochlorperazine 10 mg PO every 6 hours 2
  • Haloperidol 0.5-1 mg PO every 6-8 hours 2
  • Granisetron 1-2 mg PO daily 2

Administration Tips

• If using IV promethazine, administer slowly (25 mg/min) to minimize hypotension risk 3
• Take with food to reduce gastrointestinal irritation 3
• Ensure adequate hydration during treatment 3

While promethazine remains a versatile medication with multiple indications, clinicians should be aware of its significant side effect profile and consider safer alternatives, particularly for elderly patients, those with respiratory conditions, or when using the injectable form.