What is the best course of treatment for an 18-year-old male patient with a history of Bipolar I disorder, anxiety, cannabis use disorder, immune thrombocytopenia, esophagitis, and gastroparesis, who presents with acute onset severe vomiting and abdominal pain after inhaling secondhand marijuana smoke, and has a history of daily cannabis use via vape pen, with current symptoms including dehydration, lightheadedness, midepigastric abdominal pain, and chest pain, and is currently taking metoclopramide (Reglan) and famotidine (Pepcid) for gastroparesis, and aripiprazole (Abilify) and escitalopram (Lexapro) for psychiatric conditions?

Treatment of Cannabinoid Hyperemesis Syndrome in an 18-Year-Old Male

This patient requires immediate treatment with parenteral benzodiazepines (lorazepam) as first-line therapy for acute CHS, along with IV fluid resuscitation, topical capsaicin 0.1% cream to the abdomen, and strict avoidance of opioids, while counseling strongly for complete cannabis cessation as the only definitive cure. 1

Immediate Acute Management

First-Line Pharmacotherapy

• Administer parenteral benzodiazepines, specifically lorazepam, which are the most effective acute treatment for nausea and vomiting in CHS patients based on multiple case series and prospective studies 1, 2, 3
• Benzodiazepines work through their sedating and anxiolytic effects, addressing the stress-mediated component of CHS and decreasing CB1 receptor activation in the frontal cortex 1, 2
• This patient's presentation with severe vomiting after secondhand marijuana exposure, history of daily cannabis use via vape pen, and inability to tolerate oral intake makes him an ideal candidate for parenteral benzodiazepine therapy 1

Second-Line Agent

• Haloperidol is the second-line agent for acute symptom control if benzodiazepines are insufficient 1
• Haloperidol has demonstrated superior efficacy in reducing hospital length of stay by nearly 50% (6.7 vs 13.9 hours, p=0.014) 4
• Butyrophenones like haloperidol should be prioritized over standard antiemetics, which typically fail in CHS 1, 5

Adjunctive Topical Therapy

• Apply topical capsaicin 0.1% cream to the abdomen with close monitoring for efficacy and adverse effects 1, 4
• Capsaicin activates transient receptor potential vanilloid type 1 (TRPV1) receptors and has shown consistent benefit in CHS 1, 4, 5
• This provides a mechanistically distinct approach compared to systemic antiemetics 3

Supportive Care

• Provide aggressive IV fluid resuscitation to address dehydration and electrolyte abnormalities 6, 3
• The patient's lightheadedness and inability to tolerate oral intake for 24 hours necessitates immediate volume repletion 1

Critical Medications to AVOID

Absolute Contraindications

• Never use opioids in this patient, as they worsen nausea, carry high addiction risk (particularly concerning given his cannabis use disorder), and do not address the underlying pathophysiology 1, 4
• The American Gastroenterological Association explicitly advises avoiding opioids entirely in CHS management 1

Likely Ineffective Agents

• Standard antiemetics (ondansetron, metoclopramide) are typically ineffective for CHS and should not be relied upon 1, 5, 6
• Note that the patient is already on metoclopramide for gastroparesis, which has clearly failed to prevent this acute episode 7
• Classic antiemetics may be tried initially but often fail to alleviate CHS symptoms 5

Distinguishing CHS from Cannabis Withdrawal Syndrome

Key Diagnostic Distinction

• This patient has CHS, NOT cannabis withdrawal syndrome (CWS), based on critical timing differences 1
• CHS occurs during active cannabis use or immediately after exposure (as in this case with secondhand smoke), while CWS occurs 24-72 hours after stopping cannabis 1
• The patient stopped vaping one week ago but developed acute symptoms only after secondhand marijuana exposure yesterday, confirming CHS rather than withdrawal 1
• CWS would present with irritability, anxiety, insomnia, decreased appetite, and potentially diarrhea 24-72 hours after cessation, not acute severe vomiting triggered by cannabis exposure 1

Definitive Long-Term Management

Cannabis Cessation - The Only Cure

• Complete and sustained cannabis abstinence is the only definitive treatment for CHS 1, 4, 6
• Symptoms require at least 6 months of continuous abstinence or duration equal to at least 3 typical vomiting cycles for complete resolution 1, 4
• This patient must understand that even secondhand exposure can trigger acute episodes, as demonstrated by his current presentation 1

Preventive Pharmacotherapy

• Initiate amitriptyline 25 mg at bedtime as the mainstay of long-term preventive therapy 1, 4
• Titrate weekly by 25 mg increments to reach the minimal effective dose of 75-100 mg 1, 4
• Tricyclic antidepressants are recommended by the American Gastroenterological Association for CHS prevention 1

Addiction Medicine Referral

• Refer to addiction medicine or psychiatry for comprehensive cannabis use disorder treatment 1
• This is particularly critical given his documented cannabis use disorder, Bipolar I disorder, and anxiety, which may complicate cessation efforts 1
• Provide cannabis cessation counseling and psychological support, as anxiety is a prominent feature during the cessation period 1

Special Considerations for This Patient

Psychiatric Medication Interactions

• Continue aripiprazole (Abilify) and escitalopram (Lexapro) for his Bipolar I disorder and anxiety 1
• Monitor closely during cannabis cessation, as anxiety and depressive symptoms may emerge or intensify during withdrawal 1

Gastroparesis Management

• Distinguish between CHS and gastroparesis exacerbation - the temporal relationship with cannabis exposure strongly favors CHS as the primary diagnosis 1
• Continue famotidine for esophagitis, but recognize that metoclopramide is ineffective for acute CHS episodes 1, 7

Immune Thrombocytopenia Consideration

• Rule out hematemesis or signs of GI bleeding given his immune thrombocytopenia history, though he currently denies hematemesis 1
• The American Gastroenterological Association recommends ruling out life-threatening conditions including acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, and myocardial infarction before confirming CHS diagnosis 1, 4

Common Pitfalls to Avoid

• Do not pursue exhaustive investigations once CHS is suspected; focus on making an early diagnosis to facilitate treatment 1
• Do not attribute symptoms solely to gastroparesis when the temporal relationship with cannabis exposure is clear 1
• Do not underestimate the severity - CHS frequently leads to extensive unnecessary testing when unrecognized by clinicians 4, 5, 6
• Do not assume cessation alone is sufficient acutely - this patient requires immediate pharmacologic intervention with benzodiazepines before long-term cessation strategies can be effective 1, 2