Management of Nausea and Vomiting
The best approach to managing nausea and vomiting begins with routine screening at every clinical encounter, identifying the underlying cause (chemotherapy, bowel obstruction, medications, metabolic abnormalities, gastroparesis), and initiating dopamine receptor antagonists (prochlorperazine, metoclopramide, or haloperidol) as first-line therapy, with sequential addition of 5-HT3 antagonists (ondansetron) if symptoms persist, targeting different neurotransmitter pathways for synergistic effect. 1, 2
Initial Assessment and Screening
Screen for nausea and vomiting at every outpatient visit and within 24 hours of inpatient admission, as this is a minimum standard of care given the 70-80% prevalence in cancer patients and significant impact on quality of life. 1
Identify the specific underlying cause, as treatment efficacy depends on addressing the etiology: 1
- Chemotherapy-induced (70-80% of patients on chemotherapy experience symptoms) 1
- Bowel obstruction (particularly in advanced colorectal and ovarian cancer) 1
- Constipation or fecal impaction (common with opioid use) 1, 2
- Medication adverse effects (especially opioids, anticholinergics) 1
- Metabolic abnormalities (hypercalcemia, electrolyte disturbances) 1, 3
- Brain metastases or CNS pathology 1
- Gastroparesis or gastric outlet obstruction 1, 2
Obtain complete blood count, serum electrolytes, glucose, liver function tests, and urinalysis to exclude metabolic causes and assess dehydration severity. 3
Critical pitfall: Never use antiemetics in suspected mechanical bowel obstruction, as this can mask progressive ileus and gastric distension. 2, 3
Stepwise Pharmacologic Management Algorithm
First-Line Therapy: Dopamine Receptor Antagonists
Initiate dopamine receptor antagonists as first-line therapy, titrated to maximum benefit and tolerance: 1, 2, 3
- Prochlorperazine: 5-10 mg orally 3-4 times daily (maximum 40 mg/day), or 10 mg IV/IM, or 25 mg rectal suppository 4, 5
- Metoclopramide: 10 mg orally/IV three times daily before meals, particularly effective for gastroparesis and gastric stasis 1, 2, 3
- Haloperidol: 0.5-2 mg IV/PO every 4-6 hours as needed 1, 3
For patients with prior history of opioid-induced nausea, administer prophylactic antiemetics. 1
Monitor for extrapyramidal side effects with dopamine antagonists, particularly in young males, and treat with diphenhydramine 50 mg IV if they develop. 3
Second-Line Therapy: Add 5-HT3 Antagonists
If nausea persists after 4 weeks of dopamine antagonist therapy, add ondansetron (5-HT3 antagonist) rather than replacing the first agent, as different neuroreceptors are involved in the emetic response and agents behave synergistically. 1, 2, 3
Monitor for QTc prolongation when using ondansetron, especially in combination with other QT-prolonging agents. 3
Third-Line Therapy: Additional Agents for Refractory Symptoms
For persistent symptoms despite combination therapy, add corticosteroids: 1, 2, 3
Consider olanzapine for refractory symptoms, especially helpful in patients with bowel obstruction. 1, 2
Administration Principles
Administer antiemetics on a scheduled basis rather than PRN, as prevention is far easier than treating established vomiting. 3
Use agents from different drug classes simultaneously rather than sequential monotherapy, as no single agent has proven superior for breakthrough emesis. 1, 3
Consider alternative routes (IV, rectal, sublingual) if oral route is not feasible due to ongoing vomiting. 1, 3, 4
Cause-Specific Management
Chemotherapy-Induced Nausea and Vomiting
Provide prophylaxis for acute and delayed emesis in patients receiving moderate to highly emetogenic chemotherapy. 1
Without prophylactic antiemetic therapy, highly emetic chemotherapy like cisplatin ≥50 mg/m² would almost universally result in nausea/vomiting, but optimal antiemetic therapy reduces prevalence to approximately 25%. 1
Follow specific antiemesis guidelines for chemotherapy-induced symptoms rather than general approaches. 2
Opioid-Induced Nausea
If nausea develops, assess other causes first (constipation, CNS pathology, chemotherapy, radiation, hypercalcemia). 1
If nausea persists despite as-needed regimen, administer antiemetics around the clock for 1 week, then adjust dosing. 1
If nausea persists longer than a week, reassess the cause and consider opioid rotation. 1
If opioid rotation and previous measures fail, consider neuraxial analgesics or neuroablative techniques to reduce opioid dose. 1
Gastritis or Gastroesophageal Reflux
- Use proton pump inhibitors or H2 receptor antagonists if dyspepsia is present, as patients may confuse heartburn with nausea. 2, 3
Anxiety-Related Nausea
- Add benzodiazepines such as lorazepam 0.5-1 mg IV or alprazolam 0.25-0.5 mg sublingual for anxiety-related nausea. 2, 4
Supportive Care Measures
Ensure adequate fluid intake of at least 1.5 L/day with small, frequent meals. 2
For acute vomiting with dehydration, initiate IV fluid therapy with normal saline or lactated Ringer's: 500-1000 mL bolus followed by maintenance rate. 4
Use balanced crystalloid solutions (lactated Ringer's) to avoid hyperchloremic acidosis. 4
Add dextrose to IV fluids if prolonged fasting or concern for hypoglycemia. 4
Assess and correct electrolyte abnormalities, particularly hypokalemia and hypomagnesemia from prolonged vomiting. 2, 3
Provide thiamin supplementation to prevent Wernicke's encephalopathy in patients with persistent vomiting. 2
Follow-Up and Monitoring
Follow up after treatment to assess symptom control, as this represents a minimum standard of care. 1
If symptoms persist despite intensified therapy, reassess for underlying causes and consider additional diagnostic evaluation. 1, 2
For severe, intractable vomiting that fails to respond to all measures, consider palliative sedation as a last resort. 2