What is the best first‑line management for an otherwise healthy adult who has nausea without vomiting?

Management of Nausea Without Vomiting in Otherwise Healthy Adults

For an otherwise healthy adult with nausea but no vomiting, start with metoclopramide 10 mg orally every 6 hours on a scheduled basis (not as-needed) as first-line therapy, limited to a maximum of 5 days to minimize neurological risks. 1

First-Line Pharmacologic Approach

• Metoclopramide is the preferred first-line dopamine receptor antagonist for managing nausea, providing both central antiemetic effects and peripheral prokinetic benefits 1
• Administer 10 mg orally every 6 hours on a scheduled basis rather than as-needed for persistent symptoms 1
• The maximum daily dose is 30 mg in adults, with treatment duration strictly limited to 5 days maximum to minimize the risk of tardive dyskinesia and other serious neurological adverse effects 1

Alternative First-Line Options

If metoclopramide is contraindicated or not tolerated:

• Ondansetron (5-HT3 antagonist) 4-8 mg orally twice or three times daily is an effective alternative that avoids sedation and extrapyramidal side effects 1, 2
• Ondansetron may be used as a first-line agent for most patient populations based on its safety and efficacy profile 2
• Prochlorperazine 10 mg orally every 6 hours can be considered as an alternative dopamine antagonist 3

Critical Safety Considerations and Contraindications

• Never use metoclopramide in suspected bowel obstruction, as it can worsen symptoms and cause serious complications by promoting motility against an obstruction 1, 3
• Monitor for extrapyramidal symptoms (akathisia, dystonia) with dopamine antagonists, particularly in young males and elderly patients 3, 2
• Metoclopramide must not be continued beyond 5 days without reassessing the underlying cause 1

When to Escalate or Investigate Further

Before initiating treatment, briefly assess for:

• Recent medication changes (opioids, GLP-1 agonists, antibiotics, chemotherapy) that commonly cause nausea 3
• Heavy cannabis use preceding symptom onset, which suggests Cannabis Hyperemesis Syndrome 3
• Alarm features requiring urgent evaluation: severe abdominal pain, weight loss, progressive symptoms, or signs of obstruction 3

If nausea persists beyond 4 weeks despite appropriate first-line therapy:

• Obtain targeted laboratory studies including complete blood count, comprehensive metabolic panel, liver function tests, lipase, and thyroid-stimulating hormone to exclude metabolic causes 3
• Consider adding ondansetron to metoclopramide for synergistic effect through different receptor mechanisms 3
• Perform one-time esophagogastroduodenoscopy or upper GI imaging to exclude structural lesions if symptoms remain refractory 3

Common Pitfalls to Avoid

• Do not prescribe metoclopramide as-needed (PRN) only—scheduled dosing is essential for persistent symptoms 1
• Do not continue metoclopramide beyond 5 days without reassessing the underlying cause and considering alternative diagnoses 1
• Do not use antiemetics in suspected mechanical bowel obstruction, as this masks progressive ileus and gastric distension 3
• Avoid promethazine as first-line due to excessive sedation and potential for vascular damage with intravenous administration 2