Suspected Cannabinoid Hyperemesis Syndrome in a Traveler from a Cannabis-Legal Country: A Case Report from Japan

Cannabinoid hyperemesis syndrome (CHS) is characterized by recurrent nausea, vomiting, and abdominal pain in chronic cannabis users. We report a case of suspected CHS in a 37-year-old Canadian male who presented to a Japanese emergency department (ED) with severe abdominal pain and persistent vomiting. He reported chronic cannabis use two to four times per week for several years, with the last use the day before departure from Canada. Urine drug screening was positive for tetrahydrocannabinol. Although the clinical presentation was consistent with the hyperemetic phase of CHS, a definitive diagnosis could not be established due to the single-visit nature of the encounter and incomplete acquisition of key diagnostic information. This case highlights the diagnostic challenges of CHS in foreign travelers presenting to EDs in cannabis-prohibited countries, where linguistic, cultural, and legal barriers may impede timely recognition. Early consideration of CHS and systematic history-taking are essential to avoid diagnostic delays in this population.