Successful Management of Refractory Cannabinoid Hyperemesis Syndrome With Topical Capsaicin: A Case Report With Proposed Mechanism of Action and Literature Review

Introduction: Cannabinoid hyperemesis syndrome (CHS) is a debilitating disorder of chronic, heavy cannabis users characterized by cyclic severe nausea, vomiting, and abdominal pain that is classically relieved by hot baths. Standard antiemetics often fail, and dysregulation of endocannabinoid signaling with involvement of heat-sensitive TRPV1 channels has been proposed. Topical capsaicin - a TRPV1 agonist - has been reported in small series and case reports to reproduce the hot-water effect and rapidly relieve symptoms. Case presentation: A 28-year-old man with daily high-potency cannabis use (∼2 g/day for 7 years) presented to the emergency department with 48 hours of intractable non-bilious vomiting (∼20 episodes/day), severe periumbilical cramping (8/10), and a history of similar episodic flares relieved by prolonged hot showers. Initial ED therapy (IV fluids, ondansetron, metoclopramide, pantoprazole) produced minimal benefit; labs showed hypokalemic, hypochloremic metabolic alkalosis and pre-renal azotemia, with otherwise unremarkable imaging and enzymes. After informed consent, ∼2 g of 0.1% topical capsaicin cream was applied across the abdomen. The patient experienced an acute burning sensation for ∼15-30 minutes; retching ceased within 10 minutes, pain fell to 2/10 by 30 minutes and resolved by 90 minutes, and he tolerated oral intake. Vital signs normalized and electrolytes/renal function returned to baseline at 48-hour follow-up. He was discharged with counseling on cannabis cessation and a capsaicin tube for prodromal use. Conclusion: Topical capsaicin produced rapid, durable symptom resolution in this case of refractory CHS with only transient local discomfort. The effect is plausibly mediated by TRPV1 activation followed by peripheral desensitization, recapitulating the therapeutic hot-water response. Given consistent positive signals from case reports, series, and small pilot data, topical capsaicin is a low-risk, accessible adjunct for refractory CHS, but larger controlled studies are needed to define optimal dosing, duration, and long-term outcomes.