Management of Chronic Nausea and Vomiting with Suspected Cannabis Hyperemesis Syndrome

Diagnostic Considerations

The American Gastroenterological Association suggests that a patient's cannabis use pattern is critical in diagnosing Cannabis Hyperemesis Syndrome (CHS), requiring prolonged (>1 year) and heavy cannabis use (>4 times weekly, often daily) that precedes symptom onset 5
A definitive diagnosis of CHS requires 6 months of complete cannabis cessation or at least 3 typical cycle lengths without vomiting, according to the American Gastroenterological Association 5

The American College of Gastroenterology recommends adding a dopamine receptor antagonist (metoclopramide 10 mg three times daily before meals) as first-line therapy for nausea and vomiting, which addresses both nausea and promotes gastric emptying 1, 2, 3
The American College of Gastroenterology suggests adding ondansetron (a 5-HT3 antagonist) after 4 weeks of persistent symptoms despite pantoprazole, as indicated by the American Gastroenterological Association 1, 2, 3
The stepwise algorithm is: start dopamine antagonist → add 5-HT3 antagonist if symptoms persist → consider adding corticosteroids or olanzapine for refractory cases, as recommended by the American College of Gastroenterology 1, 3

The National Comprehensive Cancer Network recommends starting scheduled bisacodyl 10-15 mg daily with a goal of one non-forced bowel movement every 1-2 days, and adding a stool softener (senna plus docusate, 2-3 tablets twice to three times daily) for severe constipation management 4
The National Comprehensive Cancer Network suggests considering adding polyethylene glycol (1 capful in 8 oz water twice daily) or lactulose 30-60 mL twice to four times daily for more aggressive management, and ruling out fecal impaction with physical examination 4, 3

The American Society of Clinical Oncology recommends using the sublingual route for ondansetron (8 mg) during active vomiting episodes, as it improves absorption in actively vomiting patients 3
The American Society of Clinical Oncology suggests considering prescribing promethazine or prochlorperazine rectal suppositories as rescue therapy, and using intravenous or subcutaneous routes for severe episodes requiring ED visits 3, 4

The American College of Gastroenterology recommends monitoring electrolytes within 1-2 weeks given the vomiting duration and risk of hypokalemia, hypomagnesemia, and metabolic alkalosis, and weight trends to assess nutritional status 2, 6
The American College of Gastroenterology suggests monitoring extrapyramidal symptoms if using metoclopramide or haloperidol, particularly in young patients, and QTc interval if combining ondansetron with other QT-prolonging medications 1, 2

The American College of Gastroenterology recommends adding haloperidol 0.5-2 mg orally every 4-6 hours as an alternative dopamine antagonist with different receptor profile, and considering olanzapine 2.5-5 mg orally daily for refractory cases 1, 3
The American College of Gastroenterology suggests adding dexamethasone 10-20 mg IV for severe episodes, as the combination with ondansetron is superior to either agent alone, and using scheduled dosing rather than PRN 3, 4