Cannabis Use May Reduce the Effectiveness of Standard Treatment for Cyclical Vomiting Syndrome | Research

The takeaway

Among patients with cyclical vomiting syndrome, 19% used cannabis and the standard treatment (low-dose amitriptyline) worked best when patients stopped using both opioids and cannabis.

Gastroenterologists, emergency physicians, patients with cyclical vomiting syndrome

19% of CVS patients used cannabis, and cessation was part of the most effective treatment approach

What the researchers found

61% of CVS patients responded to a three-tiered treatment algorithm, with 91% of responders responding to low-dose amitriptyline alone (mean 26.5 mg). 33% used opioids and 19% used cannabis. Opioid cessation was significantly associated with treatment response (p = 0.03). While cannabis use was prevalent, the study suggested that cessation of both substances may improve treatment outcomes.

Why it matters

Cyclical vomiting syndrome is frequently linked to cannabis use, yet the interaction between cannabis, CVS treatment, and clinical outcomes has been poorly understood. This study suggests stopping cannabis may be part of effective CVS management.

The numbers in context

61% treatment response rate; 91% of responders responded to TCA alone; mean TCA dose 26.5 mg among responders; 33% used opioids; 19% cannabis; 7% both; opioid cessation associated with treatment response (p = 0.03); IBS associated with 6.59x odds of opioid use

How the study worked

Retrospective data from consecutive newly diagnosed CVS patients at a single UK tertiary neurogastroenterology clinic (January 2016 to June 2024). Patients were advised to stop opioids and cannabis and started on low-dose amitriptyline with stepwise escalation if needed.

What this study cannot tell us

Retrospective design at a single tertiary center, small sample limits statistical power for cannabis-specific analyses, cannot separate cessation effects from treatment effects, patients who stopped substances may have been more motivated overall, UK healthcare context

How to read the evidence

Single-center retrospective cohort; provides real-world treatment data but limited ability to isolate cannabis-specific effects

When this study was published

Published 2025

The bigger picture

Cannabis is paradoxically both a reported remedy for nausea and a recognized cause of cyclical vomiting syndrome (cannabinoid hyperemesis syndrome). This study adds evidence that cannabis use may interfere with standard CVS treatment, supporting cessation as part of clinical management.

Questions still open

How much of the treatment response improvement is from stopping cannabis vs. the amitriptyline itself? Is cannabis-associated CVS a distinct entity from other CVS? Would prospective studies with controlled cessation protocols show clearer cannabis effects?

Common questions

Does cannabis use affect treatment for cyclical vomiting syndrome?

In this study, CVS treatment worked best when patients stopped using cannabis and opioids alongside starting low-dose amitriptyline. Opioid cessation was statistically linked to better outcomes, and cannabis cessation was recommended as part of the treatment protocol.

How common is cannabis use among CVS patients?

19% of CVS patients in this UK study used cannabis, with an additional 7% using both cannabis and opioids.

Read the original research

Impact of Opioid and Cannabis Use on Low-Dose Amitriptyline Efficacy in Cyclical Vomiting Syndrome: A Real-World Study in the United Kingdom.

Neurogastroenterology and motility, 37(6), e70007

View on PubMed ↗Publisher’s paper ↗

Citation

Butt, Mohsin F; Cefalo, Francesca; Sbarigia, Caterina; Dhali, Arkadeep; Corsetti, Maura. (2025). Impact of Opioid and Cannabis Use on Low-Dose Amitriptyline Efficacy in Cyclical Vomiting Syndrome: A Real-World Study in the United Kingdom.. Neurogastroenterology and motility, 37(6), e70007. https://doi.org/10.1111/nmo.70007