How should I manage a patient with severe abdominal pain after smoking five joints of cannabis?

Management of Severe Abdominal Pain After Heavy Cannabis Use

This patient most likely has Cannabinoid Hyperemesis Syndrome (CHS), and you should immediately administer haloperidol 5 mg IV (or droperidol) as first-line treatment, provide IV fluids for rehydration, apply topical capsaicin 0.1% cream to the abdomen, and strongly counsel for complete cannabis cessation as the only definitive cure. 1, 2

Immediate Diagnostic Approach

Suspect CHS in any patient presenting with severe abdominal pain, nausea, and vomiting after heavy cannabis use (5 joints qualifies as heavy use, exceeding the 1.5 g/day threshold). 1, 2 Key diagnostic features to look for include:

• Stereotypical episodic vomiting occurring at least 3 times annually with acute onset 2
• Compulsive hot water bathing behavior - ask specifically if the patient has been taking long hot showers or baths for symptom relief, which occurs in 71% of CHS cases 2, 3
• Cannabis use >1 year before symptom onset and frequency >4 times per week 2, 3
• Abdominal pain that accompanies the vomiting episodes 3

Critical pitfall: You must first rule out life-threatening conditions before attributing symptoms solely to CHS. Specifically exclude acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, and myocardial infarction. 2, 3 While cannabis-induced pancreatitis is rare, it has been reported and should be considered if lipase is elevated. 4

Acute Pharmacological Management

First-Line Treatment: Butyrophenones

Administer haloperidol 5 mg IV as the initial dose, which has been shown to reduce hospital length of stay by nearly 50% (6.7 vs 13.9 hours, p=0.014) compared to standard antiemetics. 2, 3 This is far superior to ondansetron or metoclopramide, which are generally ineffective for CHS. 1, 5

• Add lorazepam 2 mg IV for anxiolysis and enhanced symptom control, as benzodiazepines address the stress-mediated component of CHS and have shown consistent effectiveness. 2, 3, 6
• Alternative butyrophenone: Droperidol can be used if haloperidol is unavailable 1, 2
• For ongoing symptoms: Haloperidol 0.5-2 mg PO or IV every 4-6 hours can be repeated 2

Safety monitoring for haloperidol:

• Obtain baseline ECG and monitor QTc interval due to risk of QT prolongation and arrhythmias 2
• Have diphenhydramine 25-50 mg IV available for dystonic reactions 2
• Use lower doses (0.5-1 mg) in elderly, frail, or debilitated patients 2
• Avoid entirely in patients with Parkinson's disease or dementia with Lewy bodies 2

Adjunctive Therapies

Apply topical capsaicin 0.1% cream to the abdomen, which activates TRPV1 receptors and provides symptom relief through the same mechanism as hot showers. 1, 2, 3

Alternative antiemetics if butyrophenones are contraindicated:

• Promethazine 12.5-25 mg IV (central line only) every 4 hours 2
• Olanzapine 2.5-5 mg PO BID for refractory cases 2
• Ondansetron 16 mg IV may be used but is significantly less effective than haloperidol for CHS 2, 5

Supportive Care

Provide aggressive IV fluid resuscitation to correct dehydration and electrolyte abnormalities, which are common in CHS patients. 1, 2 Assess for dehydration by checking skin turgor, mucous membrane moisture, capillary refill, and mental status. 2

Critical Medication Avoidance

Do NOT administer opioids - they are contraindicated in CHS because they worsen nausea, have high addiction risk, and provide no benefit. 1, 2, 3, 7, 5 This is a common pitfall that prolongs suffering and increases complications.

Avoid benzodiazepines as first-line monotherapy - while they are effective as adjuncts to haloperidol, they should not be used alone as primary treatment. 5

Definitive Management: Cannabis Cessation Counseling

Cannabis cessation is the ONLY definitive cure for CHS and must be strongly recommended. 1, 2, 3, 6 Complete and persistent resolution of symptoms requires at least 6 months of continuous cannabis abstinence. 3

Key counseling points:

• Explain that continued cannabis use will lead to recurrent episodes of severe symptoms 1, 6
• Address the paradox that patients often report cannabis helps their symptoms, which perpetuates the cycle 2
• Warn that modern cannabis products contain dramatically higher THC concentrations than historical products, increasing CHS risk 2, 3
• Provide referral to addiction services or psychiatry for cannabis cessation support 8

Long-Term Prevention Strategy

Initiate amitriptyline 25 mg at bedtime, titrating weekly to reach a target dose of 75-100 mg for prevention of recurrent episodes. 1, 2, 3, 6 Tricyclic antidepressants are the mainstay of preventive therapy and require doses in the range of 50-200 mg/day to achieve symptom control. 6

Once the patient achieves remission and maintains cannabis abstinence for 6-12 months, you can taper the amitriptyline dose with the goal of discontinuation in the majority of patients. 6

Special Considerations for Cannabis Withdrawal

If the patient is hospitalized, be aware that Cannabis Withdrawal Syndrome (CWS) can begin 24-72 hours after cessation and includes symptoms of irritability, anxiety, insomnia, decreased appetite, restlessness, and physical symptoms like abdominal pain, tremors, sweating, and fever. 8, 2

Supportive care for CWS may include:

• Gabapentin for symptom management 8, 2
• Nabilone, nabiximols, or dronabinol for patients with severe withdrawal symptoms 8, 2
• Consider these synthetic cannabinoids only for patients consuming >1.5 g/day of smoked cannabis or >20 mg/day THC oil 8

Disposition and Follow-Up

Discharge criteria: Resolution of vomiting, ability to tolerate oral fluids, adequate pain control, and stable vital signs. 2

At discharge, provide:

• Clear instructions on cannabis cessation as the only cure 1, 6
• Prescription for amitriptyline with titration schedule 1, 6
• Referral to addiction medicine or psychiatry for cessation support 8
• Education that CHS will recur with any resumption of cannabis use 3, 6