What is the best course of treatment for a patient experiencing vomiting due to marijuana (cannabis) use?

Treatment of Vomiting Due to Marijuana Use

The first priority is determining whether this is Cannabinoid Hyperemesis Syndrome (CHS) versus Cannabis Withdrawal Syndrome (CWS), as they present oppositely but both cause vomiting—CHS occurs during active chronic use while CWS occurs after cessation. 1, 2

Diagnostic Differentiation

Cannabinoid Hyperemesis Syndrome (CHS)

• Heavy, prolonged cannabis use (>4 times weekly for >1 year) preceding symptom onset 1, 3
• Stereotypical cyclic vomiting episodes (≥3 annually) during active use 1, 3
• Pathognomonic hot water bathing behavior (present in 44-71% of cases) for symptom relief 1, 4
• Abdominal pain and weight loss commonly present 5, 6

Cannabis Withdrawal Syndrome (CWS)

• Symptom onset 24-72 hours after cannabis cessation 2
• Nausea, stomach pain, irritability, anxiety, and insomnia 2
• Occurs in approximately 47% of regular users after stopping 2
• Higher risk with consumption >1.5 g/day inhaled, >20 mg/day THC oil, or >300 mg/day CBD oil 1, 2

Acute Management of CHS

First-Line Pharmacologic Treatment

Haloperidol is the most effective acute antiemetic for CHS, dosed at 5 mg IV initially, with option to add lorazepam 2 mg IV for anxiolysis. 4, 3 For ongoing symptoms, use haloperidol 0.5-2 mg PO/IV every 4-6 hours. 4

Alternative Antiemetic Options

• Droperidol (butyrophenone class, similar efficacy to haloperidol) 1, 7
• Promethazine 12.5-25 mg IV (central line only) every 4 hours 4
• Olanzapine 2.5-5 mg PO BID for refractory cases 4, 3
• Ondansetron 16 mg PO/IV daily may be tried but has limited efficacy compared to dopamine antagonists 4, 3

Non-Pharmacologic Acute Interventions

Topical capsaicin 0.1% applied to the abdomen activates transient receptor potential vanilloid type 1 receptors and provides symptom relief. 4, 3, 7 Hot showers or baths provide temporary relief and serve as a diagnostic clue. 3, 8

Critical Safety Considerations

• Have diphenhydramine 25-50 mg PO/IV available for dystonic reactions from haloperidol 4
• Alternative: benztropine 1-2 mg IV/IM for extrapyramidal symptoms 4
• Avoid opioids entirely—they worsen nausea, carry addiction risk, and do not address underlying pathophysiology 1, 4, 3
• Monitor QT interval with haloperidol use 4

Acute Management of Cannabis Withdrawal Syndrome

Supportive Care

For significant CWS symptoms in patients consuming high amounts of cannabis, nabilone or nabiximols substitution is appropriate. 2 Gabapentin may also be beneficial. 1, 4

Symptomatic Treatment

• Ondansetron may be tried for nausea, though efficacy is often limited 2
• Standard antidiarrheal agents (loperamide) for GI distress 2
• Avoid opioids 2

Specialist Referral

Patients with suspected CWS should be referred to psychiatry or addiction medicine specialists who can initiate or guide treatment with nabilone or nabiximols. 2

Definitive Long-Term Management

Cannabis Cessation

Complete cannabis cessation is the only definitive cure for CHS and requires 6+ months of abstinence for resolution. 1, 3, 6 This is non-negotiable for long-term symptom control. 3, 7

Prophylactic Pharmacotherapy for CHS

Tricyclic antidepressants (amitriptyline) are the mainstay of preventive therapy: start at 25 mg at bedtime and titrate weekly to reach 75-100 mg. 1, 4, 3 This is recommended by the American Gastroenterological Association for prevention. 3

Psychological Support

Provide cannabis cessation counseling and psychological support, as anxiety and depression are common comorbidities. 2, 3 Co-management with psychiatry is appropriate for patients with extensive psychiatric comorbidity or treatment resistance. 3

Common Pitfalls to Avoid

• CHS is often underdiagnosed due to limited clinician awareness 4
• Patients may report cannabis helps their symptoms, leading to continued use and worsening 4
• Do not perform repeated upper endoscopy or gastric emptying studies—these are not indicated 1
• Rule out life-threatening conditions first (acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, MI) before attributing symptoms to cannabis 4, 3
• Standard antiemetics (ondansetron, metoclopramide) have limited effectiveness in CHS compared to dopamine antagonists 4, 7
• Benzodiazepines and opioids should not be first-line therapy 7