What is the best course of treatment for an 18-year-old male with a history of Bipolar I disorder, anxiety disorders, cannabis use disorder, immune thrombocytopenia, esophagitis, and gastroparesis, who presents to the ED with acute abdominal pain, severe vomiting, and dehydration after exposure to marijuana smoke?

Cannabinoid Hyperemesis Syndrome (CHS) Management in the Emergency Department

This patient requires immediate aggressive IV hydration with dextrose-containing fluids, IV lorazepam as first-line antiemetic therapy, IV haloperidol as second-line, topical capsaicin 0.1% cream to the abdomen, and IV ketorolac for abdominal pain—while avoiding all opioids—followed by mandatory cannabis cessation counseling as the only definitive cure. 1, 2

Diagnostic Confirmation

This presentation is classic for Cannabinoid Hyperemesis Syndrome, not cannabis withdrawal syndrome, based on:

• Vomiting occurred during active cannabis exposure (inhaling marijuana smoke at work), not after cessation 1, 2
• Severe repetitive vomiting (50-100 episodes) with abdominal pain following cannabis exposure 3
• History of daily cannabis use (finishing a vape pen every 10 days) meeting the >4 times per week criterion 1, 2
• Previous hospitalization for hyperemesis, indicating recurrent stereotypical episodes 3, 2
• Gastroparesis history may be misattributed; CHS frequently mimics other GI disorders 2, 4

The key distinction: Cannabis Withdrawal Syndrome causes vomiting 24-72 hours AFTER stopping cannabis, whereas CHS causes vomiting DURING active use. 1 This patient stopped using cannabis one week ago but developed acute vomiting only after re-exposure to marijuana smoke, confirming CHS rather than withdrawal. 1, 2

Immediate ED Management Protocol

Fluid Resuscitation (Priority #1)

• Administer IV dextrose-containing fluids aggressively for severe dehydration from 50-100 vomiting episodes and inability to tolerate oral intake 3
• Monitor and correct electrolyte abnormalities, particularly given the severity and duration of vomiting 3

Antiemetic Therapy (Evidence-Based Hierarchy)

First-Line: IV Benzodiazepines

• Lorazepam is the most effective acute treatment for CHS-related nausea and vomiting based on multiple prospective studies 1, 2
• Benzodiazepines provide dual benefit: antiemetic effect plus sedation, which is a therapeutic goal in itself for CHS 3, 2
• Place patient in a quiet, darker room to facilitate sedation 3

Second-Line: IV Haloperidol

• Haloperidol reduces hospital length of stay by nearly 50% (6.7 vs 13.9 hours, p=0.014) in CHS patients 2
• Alternative butyrophenone: droperidol 2

Adjunctive Therapy: Topical Capsaicin

• Apply capsaicin 0.1% cream to the abdomen to activate TRPV1 receptors, which has shown consistent benefit in case series 1, 2
• Monitor closely for skin irritation 1

Additional Antiemetics (Limited Efficacy)

• Ondansetron may be tried but efficacy is often limited in CHS 1
• Promethazine (available as rectal suppository) provides sedation benefit 3
• Prochlorperazine (rectal suppository form available) 3

Pain Management

Non-Opioid Approach (Mandatory)

• IV ketorolac as first-line non-narcotic analgesic for abdominal pain 3
• Avoid all opioids entirely—they worsen nausea, carry high addiction risk, and do not address CHS pathophysiology 1, 2

Critical Pitfall: The patient's history of Bipolar I disorder and cannabis use disorder places him at extremely high risk for narcotic addiction. 3 Even a single dose of opioids in this context is contraindicated. 1

Chest Pain Evaluation

• The chest pain worsening with vomiting likely represents musculoskeletal strain from repetitive forceful emesis, not cardiac etiology 3
• Given stable vital signs (BP 145/84, HR 88, SpO2 100%) and pain pattern (improves after vomiting stops), cardiac workup is low yield 3
• However, rule out esophageal complications given his documented esophagitis history—Mallory-Weiss tear or esophageal perforation must be excluded if hematemesis develops 3

Addressing Comorbidities

Thrombocytopenia Considerations

• Check platelet count given immune thrombocytopenia and hereditary thrombocytopenia history 3
• Avoid IM injections if platelets are significantly low; use IV routes for all medications 3
• Ketorolac use requires caution but is not absolutely contraindicated if platelets >50,000 3

Psychiatric Medication Review

• All current medications are expired (aripiprazole, escitalopram, famotidine), indicating medication non-adherence 3
• Bipolar I disorder with psychotic features requires urgent psychiatric follow-up after ED stabilization 3
• Cannabis use disorder is directly causing the current crisis; this represents a critical intervention point 1, 2

Definitive Treatment: Cannabis Cessation

The Only Cure for CHS

• Complete and sustained cannabis abstinence is the only definitive treatment for CHS 1, 2
• Symptoms require at least 6 months of continuous abstinence for complete resolution, or duration equal to 3 typical vomiting cycles 1, 2
• Provide intensive cannabis cessation counseling before ED discharge 1
• Consider referral to addiction medicine or psychiatry for integrated treatment of cannabis use disorder and Bipolar I disorder 1

Preventive Pharmacotherapy

• Initiate amitriptyline 25 mg at bedtime as the mainstay of long-term CHS prevention 1, 2
• Titrate weekly by 25 mg increments to reach minimal effective dose of 75-100 mg 1, 2
• This also addresses his anxiety disorder and may help with gastroparesis symptoms 3, 5

Disposition and Follow-Up

Discharge Criteria

• Tolerating oral fluids without vomiting 3
• Adequate pain control with non-opioid medications 3
• Electrolytes normalized 3
• Cannabis cessation counseling completed with clear understanding that re-exposure will trigger recurrence 1, 2

Mandatory Outpatient Referrals

1. Psychiatry: For Bipolar I disorder management and expired medication reconciliation 3
2. Addiction medicine: For cannabis use disorder treatment 1
3. Gastroenterology: To reassess "gastroparesis" diagnosis, which may actually be CHS 2, 5
4. Primary care: For thrombocytopenia monitoring and overall coordination 3

Patient Education (Critical)

• Any future cannabis exposure will trigger recurrence of severe vomiting episodes 1, 2
• Edible cannabis, vaping, and smoking all cause CHS—there is no "safe" route of administration 2
• Modern cannabis products have dramatically higher THC concentrations, increasing CHS risk 2
• Hot water bathing provides only temporary relief and does not treat the underlying condition 3, 2

Common Pitfalls to Avoid

1. Do not pursue extensive GI workup once CHS is suspected—this delays definitive treatment and wastes resources 1, 2
2. Do not prescribe opioids under any circumstances in this patient population 1, 2
3. Do not accept "social use" cannabis history at face value—probe specifically about daily use patterns, vaping, edibles, and "dabbing" 6
4. Do not confuse CHS with cannabis withdrawal syndrome—they require opposite management strategies 1
5. Do not attribute all symptoms to pre-existing gastroparesis—CHS is frequently misdiagnosed as other GI disorders 2, 4