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

Initial Workup for Nausea

Begin by systematically identifying the underlying cause through targeted history and diagnostic evaluation, focusing on distinguishing gastrointestinal from non-gastrointestinal etiologies, then treat based on the specific cause identified.

Essential History and Physical Examination Elements

When evaluating nausea, obtain specific details about:

• Timing and duration: Acute (< 7 days) versus chronic (≥ 4 weeks) symptoms help narrow the differential diagnosis 1, 2
• Associated symptoms: Vomiting frequency, abdominal pain, headache, vertigo, fever, or neurological symptoms 1
• Medication review: Recent additions or changes, particularly opioids, antibiotics, antifungals, and chemotherapy agents 3, 1
• Relationship to food intake: Timing relative to meals can suggest gastroparesis or other gastrointestinal motility disorders 2
• Red flag symptoms requiring urgent evaluation: Signs of bowel obstruction, severe abdominal pain, neurological deficits, or metabolic derangements 3

Initial Diagnostic Workup

For acute nausea (< 7 days): In the absence of alarm symptoms, extensive evaluation is typically unnecessary as most cases are self-limited viral syndromes or foodborne illness 1. Basic metabolic panel and pregnancy test (in women of childbearing age) are reasonable initial tests.

For chronic nausea (≥ 4 weeks): A more comprehensive evaluation is warranted 2:

• Laboratory studies: Complete metabolic panel to assess for electrolyte disturbances, renal dysfunction, hepatic disease, and hyperglycemia 3, 1
• Imaging: Consider upper gastrointestinal imaging or endoscopy to exclude mechanical obstruction, peptic ulcer disease, or malignancy 2
• Gastric emptying study: If gastroparesis is suspected based on postprandial symptom exacerbation 2
• Brain imaging: If neurological symptoms or signs of increased intracranial pressure are present 3

Specific Causes to Exclude

Before initiating empiric antiemetic therapy, systematically rule out:

• Gastrointestinal: Obstruction, gastroparesis, peptic ulcer disease, constipation 3, 2
• Metabolic: Electrolyte abnormalities, uremia, diabetic ketoacidosis, hypercalcemia 3, 1
• Neurologic: Brain metastases, increased intracranial pressure, vestibular disorders 3, 1
• Medication-induced: Review all current medications and consider discontinuation of non-essential agents 4
• Pregnancy: Always test in women of reproductive age 1
• Cardiac: Consider in appropriate clinical context, particularly in older patients 1

Initial Treatment Approach

For Acute Nausea in the Emergency Department Setting

Ondansetron is recommended as first-line therapy due to its favorable safety profile, lack of sedation, and absence of extrapyramidal side effects 5. The FDA-approved dosing is 4 mg IV over 2-5 minutes for postoperative nausea/vomiting 6.

Alternative agents if ondansetron is ineffective or contraindicated:

• Metoclopramide 10-20 mg IV/PO every 6 hours, though monitor for akathisia and extrapyramidal symptoms 4, 5
• Prochlorperazine 5-10 mg IV/PO every 6 hours 4, 5
• Promethazine may be used when sedation is desirable, but carries risk of vascular damage with IV administration 5

For Persistent or Refractory Nausea

Start with scheduled (not as-needed) dopamine antagonists as first-line treatment 4:

• Metoclopramide 10-20 mg PO/IV every 6 hours 4
• Prochlorperazine 5-10 mg PO/IV every 6 hours 4
• Haloperidol 0.5-2 mg PO/IV every 6-8 hours 4

If symptoms persist despite first-line therapy, add a 5-HT3 antagonist 4:

• Ondansetron 4-8 mg PO/IV every 8-12 hours 4
• Granisetron 1-2 mg PO daily 4

Consider adding dexamethasone 4-8 mg PO/IV daily to enhance antiemetic efficacy 4. This combination approach is particularly effective for chemotherapy-induced nausea 3.

Cause-Specific Treatments

• Medication-induced gastropathy: Proton pump inhibitors may help, as patients often cannot distinguish heartburn from nausea 3, 4
• Opioid-induced nausea: Consider opioid rotation 4
• Anticipatory nausea: Lorazepam 1-2 mg or alprazolam 0.25-0.5 mg PO three times daily, combined with behavioral therapy 3

Important Caveats and Pitfalls

• Metoclopramide carries significant risk of extrapyramidal side effects, particularly at higher doses and with prolonged use; akathisia can develop any time within 48 hours of administration 4, 5
• Start with lower doses in elderly patients due to increased sensitivity to side effects 4
• Monitor for QT prolongation with ondansetron, particularly in patients with cardiac risk factors 6
• 5-HT3 antagonists can cause constipation, which may worsen nausea in some patients 4
• Avoid using antiemetics to mask progressive ileus in postoperative patients or those receiving chemotherapy 6
• Droperidol, while highly effective, is now limited to refractory cases due to FDA black box warning regarding QT prolongation 5
• Benzodiazepines should not be abruptly discontinued and require gradual dose reduction 4

Non-Pharmacological Measures

Implement supportive care alongside pharmacotherapy:

• Intravenous fluid and electrolyte replacement as needed 1, 7
• Small, frequent meals rather than large meals 4
• Avoidance of trigger foods (fatty, spicy, or strong-smelling foods) 4
• Behavioral therapy techniques including guided imagery and hypnosis for anticipatory nausea 3
• Acupuncture may be considered for persistent symptoms 4

When Standard Therapy Fails

For truly refractory nausea despite combination therapy, consider 4:

• Continuous IV/subcutaneous infusion of antiemetics
• Combination therapy using medications from different pharmacologic classes
• Referral to gastroenterology for specialized evaluation if chronic symptoms persist