What is the likely diagnosis and recommended treatment for a 14‑year‑old male chronic marijuana user presenting with recurrent vomiting and abdominal pain, with normal lipase, amylase, complete blood count, creatinine, urinalysis, and abdominal x‑ray?

Cannabinoid Hyperemesis Syndrome (CHS)

This 14-year-old male with chronic marijuana use presenting with recurrent vomiting and abdominal pain, with normal laboratory and imaging studies, most likely has Cannabinoid Hyperemesis Syndrome (CHS), and the definitive treatment is complete cannabis cessation for at least 6 months. 1

Diagnostic Confirmation

The clinical presentation strongly suggests CHS based on the following criteria 1:

• Stereotypical episodic vomiting in the context of chronic cannabis use (present in this case) 1
• Normal laboratory workup including lipase (40), amylase (63), CBC, creatinine (1.02), and urinalysis—which is typical for CHS as it is a functional disorder, not structural 1
• Normal abdominal imaging (x-ray in this case), which helps exclude life-threatening conditions like bowel obstruction, acute abdomen, mesenteric ischemia, or pancreatitis 1

Key Diagnostic Questions to Ask

You must specifically inquire about 1, 2:

• Hot water bathing behavior: Does he take compulsive hot showers or baths for symptom relief? This pathognomonic feature occurs in 44-71% of CHS cases 1, 2
• Cannabis use pattern: Duration of use >1 year before symptom onset and frequency >4 times per week are diagnostic criteria 1
• Episode frequency: Does he have ≥3 vomiting episodes annually with acute onset? 1

Critical Differential: Cannabis Withdrawal Syndrome vs. CHS

The timing of vomiting relative to cannabis use is the key distinguishing feature 2, 3:

• CHS: Vomiting occurs during active chronic cannabis use 2, 3
• Cannabis Withdrawal Syndrome (CWS): Vomiting occurs after stopping cannabis, with symptom onset 24-72 hours after cessation 2

Since this patient is an active marijuana user presenting with symptoms, CHS is the correct diagnosis, not withdrawal 2, 3.

Acute Management in the Emergency Department

First-Line Treatment

Benzodiazepines, specifically lorazepam (0.5-2 mg every 4-6 hours), are the most effective acute treatment for CHS-related nausea and vomiting based on multiple prospective studies 2, 3. They work through both antiemetic effects via sedation and anxiolytic properties that address the stress-mediated component 2.

Second-Line Treatment

Haloperidol or droperidol are second-line agents that can reduce hospital length of stay by nearly 50% (6.7 vs 13.9 hours, p=0.014) 2, 3, 4.

Adjunctive Therapy

Topical capsaicin 0.1% cream applied to the abdomen activates TRPV1 receptors and provides consistent symptom relief 1, 2, 3.

Medications to AVOID

Never use opioids in CHS patients—they worsen nausea, carry high addiction risk, and do not address the underlying pathophysiology 1, 2, 3. This is a critical pitfall to avoid.

Standard antiemetics (ondansetron, promethazine) often fail in CHS, though they may be tried initially 2, 4.

Definitive Long-Term Management

Cannabis Cessation: The Only Cure

Complete cannabis cessation is the only definitive treatment for CHS 1, 2, 3. The patient and family must understand that:

• Symptoms require at least 6 months of continuous abstinence for complete resolution, or abstinence duration equal to 3 typical vomiting cycles 1, 2, 3
• Partial reduction or switching to edibles will not work—complete cessation is mandatory 1
• Recidivism is high (>40% in some series), so ongoing support is essential 1

Preventive Pharmacotherapy

Tricyclic antidepressants, specifically amitriptyline, are the mainstay of long-term preventive therapy 1, 2, 3:

• Start at 25 mg at bedtime 1, 2
• Titrate weekly by 25 mg increments 1, 2
• Target dose: 75-100 mg at bedtime 1, 2
• Can be initiated even while working toward cannabis cessation 2

Psychosocial Support

Refer to addiction medicine specialists or substance use counselors for cannabis cessation support 2, 3. This is particularly important in adolescents, where co-management with psychiatry may be helpful given the high rates of anxiety and depression comorbidity 1, 2.

Common Pitfalls to Avoid

• Do not pursue exhaustive investigations once CHS is suspected—this leads to unnecessary testing, repeated ED visits, and diagnostic delay averaging several years 1, 5, 6
• Do not assume hot water bathing is pathognomonic—while present in 71% of CHS cases, it also occurs in 44% of cyclic vomiting syndrome cases 2, 7
• Do not use opioids for pain management—they exacerbate nausea and have high addiction potential in this population 1, 2, 3
• Do not accept patient denial of the cannabis-symptom connection—many patients remain uncertain about the role of cannabis and attribute symptoms to food, alcohol, or stress 1

Prognosis and Follow-Up

• Symptoms will only resolve with complete and sustained cannabis abstinence 1, 2, 3
• Anxiety and depression may emerge or intensify during withdrawal, requiring concurrent mental health assessment 2
• Close follow-up is essential to monitor for relapse and provide ongoing cessation support 1, 2