What is the most likely diagnosis for a 29-year-old woman with daily morning vomiting, weight loss, anorexia, frequent dizziness, and daily use of high‑potency cannabis?

Cannabinoid Hyperemesis Syndrome (CHS)

This patient almost certainly has cannabinoid hyperemesis syndrome (CHS), a disorder of gut-brain interaction caused by chronic high-potency cannabis use that presents with cyclic vomiting, weight loss, and anorexia in young adults. 1

Clinical Diagnosis

The patient's presentation matches the diagnostic criteria for CHS established by the American Gastroenterological Association 1:

• Age and demographics: Mean age of CHS is 30 years, and this patient is 29 years old 1
• Cannabis use pattern: Daily concentrated (high-potency) cannabis use meets the frequency requirement of more than 4 times per week 1
• Stereotypical vomiting: Morning vomiting pattern is characteristic of the cyclic nature of CHS 1
• Associated symptoms: Weight loss and anorexia are core features, along with the nausea 1

The dizziness is likely secondary to dehydration and electrolyte abnormalities from chronic vomiting and poor oral intake. 1

Key Diagnostic Features to Assess

Ask specifically about:

• Hot water bathing behavior: Does she take prolonged hot showers or baths for symptom relief? This occurs in 71% of CHS patients and is a strong clinical indicator 1
• Duration of cannabis use: CHS typically requires mean duration of 6.6 years of use before symptom onset, though high-potency concentrates ("dabs") can cause symptoms more rapidly 2
• Cyclic pattern: Does she have symptom-free intervals between vomiting episodes? CHS requires 3 or more episodes annually 1

Critical Differential Diagnoses to Exclude First

Before confirming CHS, you must rule out life-threatening conditions 1:

• Pregnancy: Mandatory urine pregnancy test in any woman of reproductive age with vomiting
• Acute abdomen: Assess for peritoneal signs
• Bowel obstruction: Check for distension, absent bowel sounds
• Pancreatitis: Order lipase level
• Gastroparesis: Consider if diabetic or other risk factors present

Management Algorithm

Immediate Actions

1. Confirm cannabis cessation is the definitive treatment: Symptoms resolve after 6 months of complete abstinence or duration equal to 3 typical vomiting cycles 1

2. Acute symptom management (if currently symptomatic) 1:

   • Topical capsaicin 0.1% cream: Apply to abdomen with close monitoring
   • Haloperidol, promethazine, olanzapine, or ondansetron: For antiemetic effect
   • Benzodiazepines: For anxiety and nausea
   • AVOID opioids: They worsen nausea and carry high addiction risk 1

3. Long-term management 1:

   • Cannabis cessation counseling: This is the only curative treatment
   • Amitriptyline: Start 25 mg at bedtime, titrate weekly by 25 mg increments to reach 75-100 mg (minimal effective dose) 1
   • Consider co-management with psychiatry/psychology: Anxiety and depression are very common comorbidities, and many patients remain uncertain about cannabis's role despite diagnosis 1

Common Pitfalls

• Patient denial or minimization: Many patients don't connect their symptoms to cannabis use and attribute them to food, alcohol, or stress instead 1
• Paradoxical perception: Patients often report cannabis "helps" their symptoms, not recognizing it as the cause 1
• Misdiagnosis as eating disorder: CHS can mimic purging behaviors, especially in patients with psychiatric comorbidity 3
• High recidivism: Over 40% of patients may eventually stop treatment, but relapse to cannabis use is common 1

Pathophysiology Context

The concentrated cannabis she uses has high THC content, which overstimulates CB1 receptors in the dorsal vagal complex (the brain's vomiting center), paradoxically causing vomiting despite cannabis's typical antiemetic effects 1. Peripheral CB1 receptor activation also impairs gastric motility and acid secretion, contributing to symptoms 1.

The definitive diagnostic test is symptom resolution with sustained cannabis abstinence—no other intervention will cure this condition. 1