Which antiemetic should be given to an adult acutely intoxicated with alcohol?

Ondansetron is the preferred antiemetic for acute alcohol intoxication

For an acutely intoxicated adult, ondansetron (a 5-HT3 receptor antagonist) should be the first-line antiemetic due to its superior safety profile—specifically, it does not cause sedation or extrapyramidal side effects, both of which are particularly problematic in intoxicated patients.

Why Ondansetron is Optimal

In the emergency department setting, ondansetron has emerged as the safest and most effective choice for nausea and vomiting in intoxicated patients 1. The key advantages are:

• No sedation: Critical when you need to monitor mental status and cannot distinguish between alcohol-induced CNS depression and drug-induced sedation
• No extrapyramidal effects: Avoids akathisia and dystonic reactions that complicate clinical assessment
• No respiratory depression: Unlike sedating antihistamines, it won't compound alcohol's respiratory depressant effects
• Efficacy comparable to other agents: As effective as promethazine without the adverse effect burden 1

Dosing for Alcohol Intoxication

• Ondansetron 8 mg IV or PO as a single dose
• Can repeat 8 mg if needed (up to 16-24 mg total) 2
• IV administration preferred if patient is actively vomiting or unable to tolerate oral medication

What to Avoid and Why

Promethazine causes excessive sedation and has risk of tissue damage with IV administration—you cannot reliably assess neurological status when the patient is sedated from both alcohol and antiemetic 1.

Prochlorperazine and metoclopramide carry significant risk of akathisia (restlessness that can be mistaken for agitation from intoxication) and dystonic reactions, which can occur up to 48 hours after administration 3, 1. These extrapyramidal symptoms are particularly problematic because:

• They mimic or mask signs of alcohol withdrawal
• They create diagnostic confusion in an already complex clinical picture
• They require additional treatment with diphenhydramine

Droperidol was historically effective but carries an FDA black box warning for QT prolongation and should be reserved only for refractory cases 1.

Clinical Pitfalls to Avoid

1. Don't assume nausea is only from alcohol: Intoxicated patients provide unreliable histories and may have co-ingestions, head trauma, or other serious pathology 4, 5

2. Monitor for aspiration risk: Even with antiemetics, intoxicated patients have impaired protective airway reflexes—position appropriately and reassess frequently 5

3. Watch for QT prolongation: While ondansetron is safer than alternatives, it can still prolong QT interval 6. Avoid in patients with known QT prolongation or concurrent QT-prolonging drugs

4. Don't use antiemetics to facilitate discharge: The goal is symptom relief and prevention of aspiration, not to expedite ED throughput. Patients need appropriate observation regardless of antiemetic response 7

Alternative Approach if Ondansetron Unavailable

If ondansetron is not available:

• Metoclopramide 10 mg IV (slow infusion over 15 minutes to reduce akathisia risk)
• Have diphenhydramine 25-50 mg IV immediately available to treat extrapyramidal reactions
• Accept that you'll need closer monitoring for both sedation and movement disorders

The evidence consistently supports ondansetron as first-line because it allows you to treat the symptom without adding layers of complexity to an already challenging clinical scenario 1.