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

Initial Workup and Management of Nausea

The initial workup for a patient presenting with nausea should include a thorough assessment for specific causes including medication side effects, constipation, central nervous system pathology, gastrointestinal disorders, metabolic abnormalities, and hypercalcemia. 1

Initial Assessment

• Evaluate for specific underlying causes of nausea including medication side effects (particularly opioids), constipation, central nervous system pathology, gastrointestinal disorders, and metabolic abnormalities 1
• Review current medications that may be causing nausea, with particular attention to opioids which commonly cause nausea 2
• Determine whether nausea is acute (up to 7 days) or chronic (4 weeks or longer) as this affects the diagnostic approach 3
• Assess for alarm symptoms that require urgent evaluation including unexplained fever, neck stiffness, focal neurological symptoms, impaired memory, altered consciousness, or personality changes 2
• Document associated symptoms, timing of onset, exacerbating or relieving factors, and relationship with food intake to narrow the differential diagnosis 3

Diagnostic Testing

• Initial diagnostic testing should include basic laboratory tests (complete blood count, comprehensive metabolic panel, pregnancy test in women of childbearing age) and plain radiography if indicated 4
• For patients with persistent symptoms or alarm features, consider additional testing such as upper endoscopy or computed tomography of the abdomen based on clinical suspicion 4
• Rule out obstruction in patients with severe nausea, especially if accompanied by abdominal pain or distention 2

Initial Management

• For opioid-induced nausea, consider dopamine receptor antagonists such as prochlorperazine 10 mg PO every 6 hours or metoclopramide 10-20 mg PO every 6 hours 2
• For acute nausea of unknown etiology, begin with antiemetics targeting the dopamine pathway such as prochlorperazine 5-10 mg every 6-8 hours, metoclopramide 10-20 mg every 6 hours, or haloperidol 0.5-1 mg every 6-8 hours 1
• For severe nausea, particularly related to chemotherapy or radiation, consider serotonin (5-HT3) receptor antagonists such as ondansetron 4-8 mg PO every 8-12 hours 5
• Promethazine 12.5-25 mg every 4-6 hours can be effective for nausea and vomiting when other agents fail 6

Management of Persistent Nausea

• If nausea persists despite an as-needed regimen, administer antiemetics around the clock for 1 week and then change to as-needed dosing 2
• Consider adding medications with different mechanisms of action for synergistic effect rather than replacing one antiemetic with another 2
• For persistent nausea, consider adding serotonin receptor antagonists such as ondansetron which have a lower rate of CNS effects 2
• Alternative agents for refractory nausea include scopolamine, dronabinol, or olanzapine 2
• Corticosteroids such as dexamethasone can be beneficial for reducing persistent nausea, particularly in combination with metoclopramide and ondansetron 2

Specific Nausea Scenarios

Chemotherapy-Induced Nausea

• For highly emetogenic chemotherapy, use a three-drug combination of NK1 receptor antagonist, 5-HT3 receptor antagonist, and dexamethasone 2
• For moderately emetogenic chemotherapy, use a two-drug combination of a 5-HT3 receptor antagonist and dexamethasone 2

Opioid-Induced Nausea

• Rule out constipation as a cause of nausea in patients taking opioids 2
• Consider prophylactic antiemetics during initial opioid therapy, as tolerance to nausea typically develops within a few days 2
• If nausea persists for longer than a week despite treatment, consider opioid rotation 2

Radiation-Induced Nausea

• For high-emetic-risk radiation therapy, use a two-drug combination of a 5-HT3 receptor antagonist and dexamethasone before each fraction 2
• For moderate-emetic-risk radiation therapy, use a 5-HT3 receptor antagonist before each fraction, with or without dexamethasone 2

Supportive Measures

• Ensure adequate hydration and electrolyte replacement in patients with significant vomiting 3
• Recommend dietary modifications including small, frequent meals and avoidance of trigger foods 3
• Consider non-pharmacologic approaches such as acupuncture or cognitive behavioral therapy for chronic nausea 1

Follow-up

• Schedule appropriate follow-up to assess response to antiemetic therapy 1
• Document patient's response to antiemetic regimen and any adverse effects 1
• Provide patient education regarding medication side effects and when to contact healthcare provider 1