What is the best treatment for a patient with cannabis-induced nausea and vomiting (N/V)?

Treatment of Cannabis-Induced Nausea and Vomiting

For acute cannabis-induced nausea and vomiting, initiate treatment with topical capsaicin cream (0.1%) applied to the abdomen, combined with a benzodiazepine such as lorazepam 0.5-1 mg IV/PO, and haloperidol 0.5-2 mg IV/PO, as these agents have the strongest evidence for cannabinoid hyperemesis syndrome (CHS) and are more effective than standard 5-HT3 antagonists like ondansetron. 1, 2

Acute Management in the Emergency Department or Clinic

First-Line Therapy

• Apply topical capsaicin (0.1%) cream to the abdomen with close monitoring, as this activates transient receptor potential vanilloid type 1 receptors and has shown effectiveness in multiple case series for CHS. 1, 2
• Administer lorazepam 0.5-1 mg IV or PO every 4-6 hours as benzodiazepines are the most frequently reported effective treatment across multiple studies for acute CHS symptoms. 1, 2
• Add haloperidol 0.5-2 mg IV/PO every 4-6 hours as a dopamine receptor antagonist, which has demonstrated efficacy specifically for CHS in case series. 1, 2

Important Caveat About Standard Antiemetics

• Ondansetron and other 5-HT3 antagonists are notably LESS effective for cannabis-induced nausea compared to other causes of nausea, as CHS operates through different mechanisms than chemotherapy-induced or postoperative nausea. 3, 2
• Standard antiemetics like ondansetron, promethazine, and metoclopramide may provide minimal benefit and should not be first-line for confirmed CHS. 3, 4

Supportive Measures

• Allow hot water bathing/showering, as this provides temporary symptomatic relief in 71% of CHS patients through unclear mechanisms, possibly related to cutaneous vasodilation or temperature receptor activation. 1
• Correct dehydration with IV isotonic fluids (lactated Ringer's or normal saline) if the patient has severe dehydration, as prolonged vomiting causes hypokalemia, hypochloremia, and metabolic alkalosis. 5
• Monitor and correct electrolyte abnormalities, particularly potassium and magnesium, as these are commonly depleted with cyclic vomiting. 5

Transitional and Long-Term Management

Definitive Treatment

• Counsel the patient that complete cannabis cessation is the only definitive cure, with symptom resolution expected after 6 months of abstinence or at least 3 typical vomiting cycle durations. 1
• Initiate amitriptyline 25 mg at bedtime, titrating weekly by 25 mg increments to reach 75-100 mg at bedtime for long-term prophylaxis while the patient works toward cannabis cessation. 1

Bridging Therapy

• Continue topical capsaicin (0.1%) cream as needed during the transition period with monitoring for skin irritation or adverse effects. 1
• Consider combining evidence-based psychosocial interventions with pharmacology for successful long-term management of cannabis use disorder. 1

Medications to Avoid

Opioids

• Do NOT use opioids (morphine, fentanyl, methadone) despite some case reports suggesting benefit, as they worsen nausea, carry high addiction risk, and are contraindicated in the management of CHS per AGA guidelines. 1

Cannabinoids

• Do NOT prescribe dronabinol or nabilone for cannabis-induced nausea, as adding more cannabinoids to treat cannabinoid toxicity is counterproductive and paradoxical. 1

Diagnostic Confirmation

Clinical Criteria for CHS Diagnosis

• Confirm stereotypical episodic vomiting occurring 3 or more times annually with cannabis use duration more than 1 year before symptom onset. 1
• Document cannabis use frequency of more than 4 times per week on average as this pattern is characteristic of CHS. 1
• Assess for compulsive hot water bathing behavior, which occurs in 71% of CHS cases and helps distinguish it from cyclic vomiting syndrome. 1

Exclude Other Causes

• Obtain complete blood count, comprehensive metabolic panel, lipase, and urinalysis to exclude metabolic causes, pancreatitis, and assess dehydration severity. 5
• Perform one-time esophagogastroduodenoscopy or upper GI imaging to exclude mechanical obstruction, gastroparesis, or structural abnormalities. 5
• Check urine drug screen to confirm cannabis use and exclude other substances. 5

Common Pitfalls to Avoid

• Do not repeatedly prescribe ondansetron or other 5-HT3 antagonists when CHS is suspected, as this delays appropriate diagnosis and treatment while exposing patients to ineffective therapy. 3, 2
• Do not stigmatize or dismiss patients with cannabis use disorder, as this creates barriers to effective treatment and cannabis cessation counseling. 5
• Do not perform repeated endoscopy or imaging unless new symptoms develop, as this increases healthcare costs without diagnostic yield. 5
• Monitor for extrapyramidal symptoms with haloperidol, particularly in young males, and treat with diphenhydramine 50 mg IV if they occur. 5
• Start with lower doses of medications in elderly or debilitated patients (e.g., haloperidol 0.5 mg, lorazepam 0.5 mg) to minimize adverse effects. 6