Cannabinoid Hyperemesis Syndrome in North America

Evaluation of Health Burden and Treatment Prevalence

Christopher N. Andrews; Renata Rehak; Matthew Woo; Ian Walker; Christopher Ma; Nauzer Forbes; Katherine Rittenbach; Joshua Hathaway; Lynn Wilsack; Andy Liu; Yasmin Nasser; Keith A. Sharkey


Aliment Pharmacol Ther. 2022;56(11):1532-1542. 

In This Article

Abstract and Introduction


Background: Cannabinoid hyperemesis syndrome (CHS) is a poorly understood vomiting disorder associated with chronic cannabis use.

Aims: To characterise patients experiencing CHS in North America and to obtain a population-based estimate of CHS treatment prevalence in Canada before and during the Covid-19 pandemic

Methods: Internet survey of 157 CHS sufferers in Canada and the United States. Administrative health databases for the province of Alberta (population 5 million) were accessed to measure emergency department (ED) visits for vomiting, with a concurrent diagnostic code for cannabis use. Three time periods of 1 year were assessed: prior to recreational cannabis legalisation (2017–2018), after recreational legalisation (2018–2019) and during the first year of the Covid-19 pandemic (2020–2021).

Results: Problematic cannabis use (defined as a CUDIT-R score ≥8) was universal among the survey cohort, and 59% and 68% screening for moderate or worse anxiety or depression, respectively. The overall treatment prevalence of CHS across all ages increased from 15 ED visits per 100,000 population (95% CI, 14–17) prior to legalisation, to 21 (95% CI, 20–23) after legalisation, to 32 (95% CI, 31–35) during the beginning of the Covid-19 pandemic (p < 0.001). Treatment prevalence among chronic cannabis users was as high as 6 per 1000 in the 16–24 age group.

Conclusion: Survey data suggest patients with CHS almost universally suffer from a cannabis use disorder, which has significant treatment implications. Treatment prevalence in the ED has increased substantially over a very short time period, with the highest rates seen during the Covid-19 pandemic.


Cannabis is the most widely used illicit substance in the world, with 2.5% of the world population consuming cannabis annually.[1] In Canada, over 2 million people over the age of 15 consumed cannabis on a daily or near-daily basis in 2018.[2] It is the most commonly used federally illegal substance in the United States with 48.2 million having used it at least once.[3] Recreational cannabis use is legal in Canada, in many US states and in parts of Europe. Whilst for some its use is not associated with harms, for others, especially heavy users, cannabis is associated with adverse health effects. Psychological adverse effects of cannabis use, such as anxiety, are well documented.[4–6] In the gastrointestinal system, the most well-described manifestation of prolonged, heavy cannabis use is cannabinoid hyperemesis syndrome (CHS). CHS defined by Rome IV is characterised by stereotypical episodic vomiting resembling cyclic vomiting syndrome (CVS) in terms of onset, duration and frequency; with presentation after prolonged use of cannabis; and relief of vomiting episodes by sustained cessation of cannabis use.[7] CHS may also be associated with bathing behaviour (prolonged hot baths or showers) as a self-soothing measure during attacks of emesis but this is not pathognomonic for CHS.[8–11] CHS shares much similarity to cyclic vomiting syndrome (CVS), with the exception of the requirement for chronic, heavy cannabis use.[10]

CHS remains a poorly studied disorder, with very little data available globally on incidence trends. Increased emergency department visits for vomiting in the US[12] and France,[13] as well as anecdotal clinical impressions from the authors' gastroenterology and emergency medicine practices suggest the prevalence may be widespread. Conversely, a questionnaire-based study from North America and the UK suggests that CHS is uncommon when strict Rome IV criteria are used.[14] The pathophysiology of CHS is likely due to dysregulation of stress responses mediated by the hypothalamic–pituitary–adrenal (HPA) axis, with a possible contribution of genetic polymorphisms.[11,15,16] During acute attacks of CHS, patients often present to the emergency department (ED) for treatment, which can lead to prolonged stays as well as multiple further investigations.[17] This, in combination with its relapsing nature, makes CHS a significant health care burden.

Currently, the generally accepted management for CHS is complete cannabis abstinence.[9,10] However, people with Cannabis Use Disorder have numerous barriers to stopping, including cravings and withdrawal symptoms, a lack of freely available cannabis-specific resources for quitting, and in many cases, one or more co-existing mental health symptoms for which patients use cannabis to self-medicate.[18] Abstinence is difficult to track, and the duration of abstinence required for symptom improvement is not defined; and as this may be months or even years, this is a further barrier to this treatment. Moreover, the Covid-19 pandemic in Canada and parts of the US has also been associated with increased cannabis sales[19,20] and preliminary reports indicate that cannabis use amongst those already using cannabis increased over the first three Covid-19 waves in Canada,[21] the US[22] and Europe,[23] potentially increasing risks for CHS. Key questions remain regarding CHS. What are the characteristics of patients who experience CHS and what is its prevalence? Here we addressed these in two aims: (1) characterise the patients experiencing CHS in North America; and (2) obtain an estimate of CHS treatment prevalence in the province of Alberta, Canada before and during the Covid-19 pandemic.