What is the recommended management for vomiting?

Management of Vomiting

Identify and Treat the Underlying Cause First

The most critical step in managing vomiting is identifying and treating the underlying etiology—whether chemotherapy-induced, bowel obstruction, gastroparesis, metabolic abnormalities, or medication-related—as this directly impacts treatment selection and patient outcomes. 1, 2

Key Etiologies to Rule Out:

• Mechanical bowel obstruction (avoid antiemetics in this setting) 1, 2
• Severe constipation or fecal impaction 1
• Gastroparesis 1
• Brain metastases 3
• Metabolic abnormalities (hypercalcemia, electrolyte disturbances) 3
• Medication adverse effects 3
• Gastritis/GERD (treat with proton pump inhibitors or H2 blockers) 1, 2

Stepwise Pharmacologic Treatment Algorithm

First-Line: Dopamine Receptor Antagonists

Begin with dopamine receptor antagonists (metoclopramide, prochlorperazine, or haloperidol) titrated to maximum benefit and tolerance. 1, 2 These agents are the recommended initial therapy for persistent vomiting across multiple guidelines. Monitor for extrapyramidal side effects, particularly with metoclopramide which carries a black box warning for tardive dyskinesia. 1

Second-Line: Add 5-HT3 Receptor Antagonists

If vomiting persists despite dopamine antagonist therapy, add a 5-HT3 receptor antagonist such as ondansetron (8 mg orally 2-3 times daily or 0.15 mg/kg IV over 15 minutes, maximum 16 mg per dose) or granisetron. 3, 1, 4 All 5-HT3 antagonists have similar effectiveness for controlling acute emesis. 3 Ondansetron is available in sublingual tablet form which may improve absorption in actively vomiting patients. 3

The key principle is adding agents from different drug classes rather than replacing one antiemetic with another, as different neuroreceptors (serotonin, dopamine, corticosteroid, neurokinin-1) are involved in the emetic response and behave synergistically when targeted simultaneously. 3, 1

Third-Line: Additional Agents for Refractory Symptoms

For persistent vomiting despite combination therapy, add one or more of the following:

• Corticosteroids (dexamethasone 12 mg orally/IV when used with aprepitant, or 4 mg daily for radiation-induced vomiting) 3, 1, 2
• Anticholinergic agents or antihistamines 1, 2
• Benzodiazepines (lorazepam 0.5-2 mg every 4-6 hours) for anxiety-related nausea, though long-term use should be avoided due to dependence risk 3, 1, 2
• Cannabinoids (nabilone) for patients who have not responded to conventional agents 3, 1
• Olanzapine (antipsychotic with superior efficacy in some refractory cases) 3, 1, 2

Fourth-Line: Intensive Interventions

For intractable vomiting:

• Continuous intravenous or subcutaneous infusion of antiemetics 1, 2
• Sedating antipsychotics (droperidol, haloperidol) particularly in emergency department settings 3
• Palliative sedation as a last resort for severe, intractable vomiting that fails all other interventions 1

Route of Administration Considerations

The oral route is often not feasible due to ongoing vomiting; therefore, rectal or intravenous therapy is frequently required. 3 Alternative formulations include:

• Ondansetron sublingual tablets 3
• Promethazine or prochlorperazine rectal suppositories 3
• Alprazolam sublingual or rectal forms 3
• Sumatriptan nasal spray (for cyclic vomiting syndrome) delivered in head-forward position 3

Scheduled vs. PRN Dosing

Around-the-clock administration of antiemetics should be strongly considered to prevent emesis, rather than PRN dosing. 3 This proactive approach is more effective than reactive treatment.

Supportive Care Essentials

• Ensure adequate hydration and fluid repletion 3
• Assess and correct electrolyte abnormalities 3
• Consider antacid therapy (proton pump inhibitors, H2 blockers) if dyspepsia is present, as patients sometimes have difficulty discriminating heartburn from nausea 3

Critical Pitfalls to Avoid

• Never use antiemetics in suspected mechanical bowel obstruction 1, 2
• Avoid antiemetics like chlorpromazine in gastroenteritis-related vomiting as they have undesirable side effects (drowsiness) that interfere with oral rehydration therapy 5
• Monitor for extrapyramidal side effects with dopamine receptor antagonists 1
• Limit benzodiazepine duration to avoid dependence 1
• When using combination therapy, target different mechanisms of action for synergistic effect rather than simply switching between agents of the same class 1

Special Population: Cyclic Vomiting Syndrome

For cyclic vomiting syndrome, most patients require combinations of 2 agents to reliably abort attacks, typically sumatriptan plus an antiemetic (ondansetron). 3 Inducing sedation is often an effective abortive strategy using promethazine, diphenhydramine, or benzodiazepines. 3