Which antiemetic and dose is appropriate to treat nausea after ketamine administration?

• A. Phenergan 12.5 mg
• B. Zofran 4 mg
• C. Dramamine 25 mg
• D. Benadryl 25 mg

Answer: (A)

The main idea here is choosing an antiemetic that both reliably stops nausea and complements ketamine’s effects in a field setting. Promethazine at 12.5 mg is effective because it blocks multiple pathways involved in nausea (histamine H1, plus anticholinergic and some dopaminergic actions) and also provides a sedative effect that can help calm the patient after ketamine’s dissociative experience. The 12.5 mg dose is a practical single adult dose that balances antiemetic effect with a manageable level of sedation and minimizes respiratory risk. While other options like ondansetron are strong antiemetics, promethazine’s added sedative benefit often makes it the preferred choice in acute casualty care after ketamine. Dramamine or diphenhydramine are less reliably effective and can add more anticholinergic burden or excessive sedation without the same targeted antiemetic impact.