Top 300 Pharmacy Drug Cards

PROMETHAZINE: Phenergan, Various

Class: Phenothiazine Antihistamine

Dosage Forms. Syrup: 6.25 mg/5 mL; Tablet: 12.5 mg, 25 mg, 50 mg; Rectal Suppository: 12.5 mg, 25 mg, 50 mg; Solution: 6.25 mg/5 mL


Common FDA Label Indication, Dosing, and Titration.

1. Motion sickness: Adults, 25 mg po or pr bid; Children 2 y and older, 12.5-25 mg po or pr bid

2. Allergy: Adults, 25 mg po or pr daily hs or 12.5 mg po or pr tid; Children 2 y and older, 25 mg po or pr daily hs or 6.25 mg po or pr tid

3. Nausea and vomiting: Adults, 25 mg po or pr q4-6h prn; Children 2 y and older, 12.5 mg po or pr q4-6h prn

Off-Label Uses. None

MOA. Promethazine hydrochloride is a phenothiazine derivative that competitively blocks histamine H1 receptors without blocking the secretion of histamine. The drug has sedative, antimotion-sickness, antiemetic, and anticholinergic effects, but it has no dopaminergic action due to a structural difference with other phenothiazines.

Drug Characteristics: Promethazine


Medication Safety Issues: Promethazine


Drug Interactions: Promethazine


Adverse Reactions: Promethazine


Efficacy Monitoring Parameters. Relief of nausea or allergy symptoms.

Toxicity Monitoring Parameters. Excessive drowsiness, decreased breathing, seizures, unusual bruising or bleeding. Monitor CBC, vital signs.

Key Patient Counseling Points. May cause drowsiness; avoid driving or other tasks requiring motor coordination. Avoid alcohol. May cause dark urine.

Clinical Pearls. Use caution in elderly, appear more sensitive to the anticholinergic adverse effects.