Management of Vomiting in Adults
For acute vomiting in adults from viral gastroenteritis, ondansetron is the preferred first-line antiemetic due to superior efficacy and safety with no sedation or extrapyramidal side effects. 1
Initial Assessment and Priorities
Fluid and electrolyte replacement is the cornerstone of management and takes priority over antiemetic therapy. 1 Antiemetics are not a substitute for adequate hydration—ensure fluid resuscitation is initiated before or concurrent with antiemetic administration. 1
Key Clinical Distinctions
The approach differs based on:
- Duration: Acute (<7 days) vs. chronic (≥4 weeks) 2
- Underlying cause: Viral illness, chemotherapy-induced, cyclic vomiting syndrome, gastroparesis, or obstruction 3, 2, 4
- Presence of alarm features: Bilious vomiting, bloody emesis, severe dehydration, altered mental status, or toxic appearance 5
Acute Vomiting Management
First-Line Pharmacologic Treatment
Ondansetron (5-HT3 receptor antagonist) 1
- Preferred for viral gastroenteritis in adults
- No sedation or extrapyramidal effects
- Available in oral, sublingual, and IV formulations
Alternative Antiemetics
Dopamine receptor antagonists 3
- Metoclopramide: Particularly useful for gastroparesis 4
- Prochlorperazine: Effective phenothiazine option 3
- Haloperidol: Reserved for refractory cases 3
Caution: Avoid chlorpromazine during oral rehydration therapy as drowsiness interferes with fluid intake 6
Non-Pharmacologic Management
- Small, frequent meals 2
- Avoidance of trigger foods 2
- Oral rehydration solutions or electrolyte-rich fluids 3
- Continue fluid administration even if vomiting persists—most fluid is retained despite apparent losses 6
Important: If vomiting occurs during oral rehydration, wait 10 minutes then resume more slowly with small sips at short intervals 6
Cyclic Vomiting Syndrome (CVS)
Abortive Treatment for Acute Episodes
Most patients require combination therapy with 2+ agents 3
Standard abortive regimen: 3
- Sumatriptan (nasal spray or subcutaneous) PLUS
- Ondansetron (sublingual tablet preferred)
Additional agents for "abortive cocktail": 3
- Promethazine (rectal suppository)—induces sedation which is therapeutic
- Alprazolam (sublingual or rectal)—sedation is a treatment goal
- Diphenhydramine or other benzodiazepines for sedation 3
Emergency Department Management
- IV dextrose-containing fluids 3
- IV antiemetics 3
- IV ketorolac as first-line non-narcotic analgesic (avoid narcotics when possible) 3
- IV benzodiazepines for sedation 3
- Quiet, darkened room environment 3
Chemotherapy-Induced Nausea and Vomiting
Breakthrough Nausea (Despite Prophylaxis)
If patient did NOT receive olanzapine prophylactically: 3
- Add olanzapine to standard antiemetic regimen (moderate-strong recommendation)
If patient already received olanzapine: 3
- Add drug from different class: NK1 receptor antagonist, lorazepam, alprazolam, dopamine antagonist, dronabinol, or nabilone 3
Adjunctive Therapy
Lorazepam is useful as adjunct but not as single-agent antiemetic 3
Medications to AVOID
Never use antimotility agents (loperamide) in patients with: 1
- Fever
- Bloody diarrhea
- Risk of toxic megacolon
Avoid chlorpromazine during oral rehydration due to sedation interfering with fluid intake 6
Chronic Vomiting (≥4 weeks)
When specific etiology is not identified: 2
- Serotonin antagonist (ondansetron) OR
- Dopamine antagonist (metoclopramide, prochlorperazine)
Use pharmacologic therapy for the shortest time necessary to control symptoms 2
Common Pitfalls
- Withholding fluids during vomiting: Continue oral rehydration even with ongoing emesis—most fluid is retained 6
- Relying solely on antiemetics: Fluid/electrolyte replacement is primary therapy 1
- Using antiemetics as monotherapy in CVS: Most patients require combination regimens 3
- Failing to reassess: For breakthrough symptoms, re-evaluate emetic risk, disease status, concurrent illnesses, and medications 3