What can be given for persistent vomiting?

Management of Persistent Vomiting

For persistent vomiting, initiate scheduled dopamine receptor antagonists (metoclopramide 10 mg PO/IV every 6 hours or prochlorperazine 10 mg PO/IV every 6 hours) as first-line therapy, and if symptoms persist after 4 weeks, add ondansetron 8-16 mg PO/IV. 1

Initial Assessment and Stabilization

Before initiating antiemetic therapy, you must identify and address life-threatening causes and metabolic derangements:

• Obtain complete blood count, serum electrolytes, glucose, liver function tests, lipase, and urinalysis to exclude metabolic causes and assess dehydration severity 1, 2
• Correct electrolyte abnormalities immediately, particularly hypokalemia, hypochloremia, hypomagnesemia, and metabolic alkalosis that develop from prolonged vomiting 1, 2
• Ensure adequate hydration with at least 1.5 L/day fluid intake and provide IV fluids if oral intake is not feasible 1, 2
• Consider thiamin supplementation to prevent Wernicke's encephalopathy in patients with persistent vomiting 1

Critical Red Flags Requiring Urgent Investigation

Never use antiemetics if mechanical bowel obstruction is suspected, as this masks progressive ileus and gastric distension 1, 2. Immediately evaluate for:

• Neurologic symptoms (headache, visual changes, altered consciousness, focal deficits) suggesting increased intracranial pressure or brain metastases 3
• Inability to tolerate liquids, severe abdominal pain, and distension indicating gastrointestinal obstruction 3
• Bilious or bloody vomiting requiring urgent surgical evaluation 1

Stepwise Pharmacologic Management

First-Line: Dopamine Receptor Antagonists

Administer antiemetics on a scheduled around-the-clock basis rather than PRN, as prevention is far easier than treating established vomiting 4, 1:

• Metoclopramide 10 mg PO/IV every 6 hours (particularly effective for gastric stasis and can be titrated to maximum benefit) 1, 5
• Prochlorperazine 10 mg PO/IV every 6 hours 4, 1
• Haloperidol 1 mg IV/PO every 4 hours as needed (alternative dopamine antagonist with different receptor profile) 4, 1

Monitor for extrapyramidal symptoms, particularly in young males, and treat with diphenhydramine 50 mg IV if they develop 1, 2, 5

Second-Line: Add 5-HT3 Antagonist After 4 Weeks

If symptoms persist despite dopamine antagonist therapy:

• Add ondansetron 8-16 mg PO/IV (acts on different receptors providing complementary antiemetic coverage) 1, 6
• Monitor for QTc prolongation when using ondansetron, especially in combination with other QT-prolonging agents 1, 2
• Ondansetron may increase stool volume/diarrhea in gastroenteritis-related vomiting 1

Combination Therapy for Refractory Cases

Combine ondansetron with dexamethasone 10-20 mg IV, as this combination is superior to either agent alone and represents category 1 evidence 1:

• Use agents from different drug classes simultaneously rather than sequential monotherapy 4, 1
• Consider alternating routes (IV, rectal, sublingual) if oral route is not feasible 4, 1
• Multiple concurrent agents in alternating schedules may be necessary 4, 1

Adjunctive Therapies

Acid Suppression

Add proton pump inhibitor or H2 blocker if dyspepsia or GERD is suspected, as patients may confuse heartburn with nausea 4, 1, 3

Anxiolytics

Consider lorazepam 0.5-2.0 mg PO/IV/SL every 4-6 hours as adjunct to primary antiemetic regimen 4

Refractory Cases

For patients who fail conventional therapy:

• Dronabinol 2.5-7.5 mg PO every 4 hours as needed (FDA-approved cannabinoid for refractory nausea) 4, 1
• Olanzapine as alternative agent 4, 1
• Scopolamine transdermal patch for vestibular-related vomiting 4

Diagnostic Workup

Perform one-time esophagogastroduodenoscopy (EGD) or upper GI imaging to exclude obstructive lesions, but avoid repeated endoscopy unless new symptoms develop 1, 2

Consider specific etiologies based on clinical context:

• Cannabis hyperemesis syndrome: Obtain detailed cannabis use history in appropriate age groups; definitive diagnosis requires 6 months cessation or 3 typical cycle lengths without vomiting 1
• Medication review: Document all current medications and timing relative to vomiting, particularly digoxin, phenytoin, or carbamazepine 3
• Metabolic causes: Test for hypercalcemia, hypothyroidism, and Addison's disease if clinically indicated 1

Non-Pharmacologic Management

• Small, frequent meals rather than large meals 1, 3
• Avoid late evening meals and elevate head of bed if GERD suspected 3
• Dietary modifications avoiding trigger foods 7

Critical Pitfalls to Avoid

• Never delay neuroimaging if any neurologic symptoms are present 3
• Do not stigmatize patients with cannabis use; offer therapy even with ongoing use as treatments can still be effective 1
• Avoid PRN dosing for recurrent vomiting; scheduled administration is essential 4, 1, 3
• Never use antiemetics in suspected mechanical obstruction 1, 2
• Monitor for dystonic reactions with metoclopramide and prochlorperazine; treat promptly with diphenhydramine 5, 8