CHS

Cannabinoid Hyperemesis Syndrome is a disorder of gut–brain interaction characterized by recurrent, stereotyped episodes of nausea, intractable vomiting, and diffuse abdominal pain in chronic (typically daily, multi-year) cannabis users, frequently accompanied by compulsive hot-water bathing that temporarily relieves symptoms. First described by Allen et al. (2004, Gut), CHS is now classified under Rome IV criteria as a functional gastroduodenal disorder, requiring stereotypical cyclic vomiting resembling cyclic vomiting syndrome, onset after prolonged cannabis use, and resolution with sustained abstinence (Drossman & Hasler 2016, Gastroenterology). Pathophysiology remains disputed ⚠️: competing hypotheses include CB1 receptor downregulation with loss of endocannabinoid antiemetic tone, TRPV1 dysregulation (supported by efficacy of topical capsaicin and hot showers, both TRPV1 agonists), lipolytic "reintoxication" from fat-stored THC, and CYP2C9/CYP2C19 pharmacogenomic variants. Epidemiological estimates vary widely (from 0.003% population prevalence to ~33% among heavy-use ED presentations; Sorensen et al. 2017 systematic review), and recognition bias complicates incidence data. → See also: Anti-emetic, TRPV1, CB1 Receptor.