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Promethazine

Brand: Phenergan

Antiemetic / antihistamineUsed for: Nausea and vomitingGastrointestinal
Boxed warning · ISMP high-alert drug

Fatal respiratory depression under age 2 (contraindicated); severe tissue injury and gangrene after injection, especially intra-arterial or under the skin.

Caution
Deep intramuscular injection is the preferred parenteral route; strongly sedating and anticholinergic. ISMP high-alert status applies to promethazine injection only.

Common side effects

  • Marked sedation
  • Dry mouth
  • Dizziness
  • Confusion in older adults

Key interactions

  • Additive sedation with opioids, alcohol, and benzodiazepines
  • Additive anticholinergic effects

Counseling points

  • Very sedating: do not drive
  • Report burning or pain at an injection site immediately
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