Cyclic Vomiting and Hot Showers in Heavy Cannabis Users. An Early Signal

Nine closely followed patients with long-term heavy cannabis use had a repeating vomiting illness. In every case, cannabis use started before the vomiting began. Seven of the nine who stopped using cannabis saw their vomiting stop during follow up. Three people who restarted after a symptom-free break relapsed, a pattern consistent with a drug-related syndrome. A striking behavioral clue showed up too. Nine of ten patients, counting one previously published case they compared against, reported abnormal washing behavior during episodes, which in later literature was described as prolonged hot bathing or showers that temporarily eased symptoms.

This was a case series from South Australia. Nineteen patients with heavy, chronic cannabis use and cyclic vomiting were identified. For ethical and legal reasons, all were counseled to stop using cannabis. Serial urine drug screens and regular clinic visits tracked use and symptoms over time. Five patients declined consent and were lost. Five more were excluded due to confounders. The authors present nine cases in detail and compare them to a previously published case labeled psychogenic vomiting. Outcomes focused on whether vomiting episodes resolved with abstinence and recurred with cannabis rechallenge.

Published in 2004, this paper helped define the clinical pattern that later came to be called cannabinoid hyperemesis syndrome. At the time, many patients with recurrent vomiting cycled through emergency departments without an explanation. An abstinence and rechallenge pattern plus the hot bathing behavior gave clinicians a recognizable profile to consider when standard tests were unrevealing.

This report is one of the earliest to outline a repeatable pattern linking long-term cannabis use with a cyclical vomiting illness that improved with abstinence and relapsed with re-exposure. It did not estimate how common the condition is, who is at highest risk, or which products or potencies track with symptoms. Most heavy cannabis users never develop cyclic vomiting, so individual susceptibility likely matters. The abnormal hot bathing behavior became a widely cited clinical clue, but it is not definitive by itself. Later reports and reviews expanded the case count, while mechanisms remain debated.

This is a small, uncontrolled case series. Half of the initially identified patients did not contribute to the main analysis because five were lost to follow up and five were excluded for confounders that are not detailed in the abstract. There was no control group and no blinding, so expectation effects from counseling could influence reporting. Reliance on self-reported symptom timing introduces recall bias, although urine drug screens strengthened the abstinence verification. Product type, dose, potency, and duration of abstinence before recovery were not standardized or fully reported.