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

The takeaway

In a small case series, stopping long-term cannabis use tracked with vomiting stopping, restarting brought it back, and most patients reported compulsive hot bathing during attacks.

Readers trying to understand where the idea of cannabinoid hyperemesis syndrome came from, clinicians facing unexplained cyclical vomiting, and researchers mapping the evidence base behind abstinence and rechallenge patterns.

7 of 9
patients monitored in the case series had vomiting resolve after they stopped using cannabis during follow up

What the researchers found

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.

Why it matters

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.

The numbers in context

- 19 identified patients with heavy cannabis use and cyclic vomiting. 10 proceeded to analysis including one earlier published case

- 7 of 9 observed cases: vomiting stopped after stopping cannabis during follow up

- 3 of 3: vomiting returned after restarting cannabis following a symptom-free period

- 9 of 10: reported abnormal washing behavior during active episodes, later characterized as prolonged hot showers or baths

How the study worked

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.

Who was studied

N=19 patients with chronic cannabis abuse and cyclical vomiting illness, South Australia

What this study cannot tell us

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.

How to read the evidence

Rated preliminary: a small case series with abstinence and rechallenge observations and urine screening, but no control group, substantial attrition from the initial pool, and limited detail on confounders and dosing.

When this study was published

Published in 2004, before widespread recognition of cannabinoid hyperemesis syndrome and before today’s higher-potency and more diverse cannabis products became common.

The bigger picture

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.

Replication

Not stated in abstract.

Funding

Not reported in abstract.

Conflicts of interest

Not reported in abstract.

Questions still open

How common is this vomiting syndrome among heavy cannabis users in the general population?
What levels of exposure, product types, or potencies are most closely linked to symptom onset and relapse?
Which biological mechanisms explain both vomiting and the relief some patients report from hot bathing?
Are there identifiable risk factors, such as genetics or coexisting conditions, that predict who develops this syndrome?
How long after stopping cannabis do symptoms typically resolve, and how durable is remission?

Common questions

What is the abnormal washing behavior described?

During vomiting episodes, most patients reported prolonged hot showers or baths that seemed to ease symptoms temporarily. This behavioral clue has since been associated with the syndrome but is not definitive on its own.

Did stopping cannabis stop the vomiting for everyone?

No. In this series, 7 of 9 closely followed patients improved after stopping. Three who resumed use after a symptom-free period relapsed, which is consistent with a rechallenge pattern.

How was cannabis use tracked?

Patients had serial urine drug screens and clinic follow up to document abstinence and relate symptom timing to use or non-use.

Read the original research

Cannabinoid hyperemesis: cyclical hyperemesis in association with chronic cannabis abuse

Gut, 53(11), 1566-1570

Gut is a leading international journal in gastroenterology and hepatology.

View on PubMed ↗

Citation

Allen, John H.; de Moore, Guy M.; Heddle, Roger; Twartz, John C.. (2004). Cannabinoid hyperemesis: cyclical hyperemesis in association with chronic cannabis abuse. Gut, 53(11), 1566-1570.