What is the initial workup and treatment for a patient presenting with nausea and vomiting?

Initial Workup and Treatment for Nausea and Vomiting

The initial workup for nausea and vomiting should include assessment for dehydration, identification of potential causes, and first-line treatment with a dopamine receptor antagonist such as metoclopramide (10-20 mg PO every 6 hours) or prochlorperazine (10 mg PO every 6 hours). 1

Assessment and Evaluation

Determine Duration and Severity

• Classify as acute (≤7 days) or chronic (≥4 weeks) 1
• Check for alarm symptoms:
  • Hematemesis
  • Severe abdominal pain
  • Fever
  • Neurological symptoms (headache, vertigo, altered mental status)
  • Signs of dehydration 1

Physical Examination

• Assess hydration status:
  • Dry mucous membranes
  • Decreased skin turgor
  • Tachycardia 1
• Evaluate for signs of bowel obstruction
• Consider neurological evaluation if headache, vertigo, or altered mental status are present 1

Identify Potential Causes

• Medications (especially opioids, antibiotics, antifungals) 2
• Gastrointestinal disorders
• Metabolic/endocrine conditions
• Neurological disorders
• Pregnancy
• Toxins or substance use 1
• Other causes to consider:
  • Radiotherapy
  • Infection
  • Electrolyte disturbances
  • Constipation
  • Gastrointestinal obstruction
  • Metastases (brain, liver, bone) 2

Treatment Approach

First-Line Treatment

• Dopamine receptor antagonists:
  • Metoclopramide 10-20 mg PO/IV every 6 hours
  • Prochlorperazine 10 mg PO/IV every 6 hours 1, 3
• Monitor for extrapyramidal side effects, especially with prolonged use 1
• For IV administration, slow infusion rate to reduce risk of akathisia 3

For Persistent Symptoms

• Add serotonin (5-HT3) receptor antagonists:
  • Ondansetron 8 mg PO/IV every 8 hours 1, 4
  • Granisetron 1 mg PO daily 1
• Ondansetron is as effective as promethazine but with less sedation and no akathisia 3

For Refractory Nausea

• Consider corticosteroids:
  • Dexamethasone 4-8 mg PO/IV daily for persistent nausea 1
• For patients who have already received olanzapine, consider adding:
  • NK1 receptor antagonist
  • Benzodiazepine (lorazepam or alprazolam)
  • Dronabinol or nabilone 2

Special Considerations

Opioid-Induced Nausea

• Begin prophylactic antiemetics when starting opioid therapy
• Metoclopramide is first-line due to both central and peripheral effects
• Tolerance typically develops within a few days 1
• Consider opioid rotation if nausea persists despite antiemetic therapy 1

Chemotherapy-Induced Nausea and Vomiting

• Treatment should be based on the emetic risk of the chemotherapy regimen:
  • High-emetic risk: NK1 receptor antagonist + 5-HT3 receptor antagonist + dexamethasone + olanzapine 2
  • Moderate-emetic risk: 5-HT3 receptor antagonist + dexamethasone 2
  • Low-emetic risk: Single agent (dexamethasone, 5-HT3 receptor antagonist, or dopamine receptor antagonist) 2
  • Minimal-emetic risk: No routine prophylaxis 2

Radiation-Induced Nausea and Vomiting

• High-emetic risk radiation: 5-HT3 receptor antagonist + dexamethasone before each fraction 2
• Moderate-emetic risk radiation: 5-HT3 receptor antagonist before each fraction, with or without dexamethasone 2

Anticipatory Nausea and Vomiting

• For patients with anticipatory emesis, behavioral therapy with systematic desensitization may be offered 2, 5
• Benzodiazepines have been documented to help in adult patients 5

Supportive Care

• Ensure adequate hydration with IV fluids if needed
• Recommend small, frequent meals
• Avoid trigger foods and strong odors
• Consider ginger supplements for mild nausea 1

Common Pitfalls to Avoid

• Failing to provide prophylactic antiemetics when starting opioid therapy in patients with prior history of nausea 1
• Prolonged use of metoclopramide without monitoring for extrapyramidal effects 1
• Treating symptoms without addressing the underlying cause, especially if symptoms persist beyond one week 1
• Using less effective antiemetics initially, as antiemetics are most effective when used prophylactically 2