25 Nov JAMA: University of Illinois Study Highlights Recents Trends in Cannabinoid Hyperemesis Syndrome

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Dr. Swartz

MedicalResearch.com Interview with:
James A. Swartz, PhD
Professor, Jane Addams College of Social Work
University of Illinois Chicago

MedicalResearch.com: What is the background for this study?

Response: For the past 5 1/2 years, my project team has been charged with monitoring the public health effects of adult cannabis use legalization in Illinois. To fulfill that obligation, we have monitored state data and have tried to keep informed about ongoing research on cannabis legalization and public health. Cannabinoid hyperemesis syndrome (CHS) rose to the surface of this continual monitoring through a growing number of publications indicating the prevalence of this condition was on the rise and clinical case reports. As context, for any readers unfamiliar with the clinical syndrome, CHS is a paradoxical reaction to long-term, heavy cannabis use. Instead of relieving nausea, cannabis in some people appears to trigger cycles of severe nausea, vomiting, and abdominal pain. Patients often present repeatedly to emergency departments, undergo extensive workups, and only much later does someone connect the dots and consider CHS. Resource use is substantial. CHS visits often involve repeat ED presentations, imaging, laboratory testing, and sometimes hospital admission. Even though CHS is rarely life-threatening, it is not a trivial condition from either the patient’s or the system’s perspective.

Most of the existing literature has been case reports, small series, or single-center studies. Those reports clearly show that CHS can be debilitating and is frequently misdiagnosed, but they don’t tell us much about the bigger picture:

• How often Cannabinoid hyperemesis syndrome is showing up in emergency departments nationally
• How those rates have changed over time, especially as cannabis policies and patterns of use have shifted
• What the typical patient profile looks like at a population level

Our goal was to step back and use a large national emergency department database to describe CHS at scale in the United States from 2016 through 2022.

MedicalResearch.com: What are the main findings?

Response:  Using a national sample of U.S. emergency department (ED) visits, we identified encounters with diagnosis codes that most consistently reflect CHS—visits where vomiting or nausea was the main reason for the ED encounter and cannabis use or cannabis use disorder was also documented, with other obvious explanations for vomiting excluded when possible. This is a conservative definition, so it likely underestimates the true burden.

A few key patterns emerged:

• CHS-related ED visits remain uncommon in absolute terms,but they represent a measurable and growing fraction of cannabis-related ED care.
• Rates were relatively stable in the earlier part of the study window and then rose sharply beginning around the COVID-19 period.That pattern is consistent with broader reports of increased cannabis use and worsening mental health and substance use during the pandemic, but our study cannot prove causation.

• Despite a decline from the peak rate seen during COVID-19, the rates remain elevated above those seen pre-COVID suggesting factors other than COVID have been driving the increase. We could not rule out whether this was attributable to greater recognition of CHS or an actual increase in the rate, or some combination thereof.

• Patients with CHS in the ED are typically younger adults,often in their 20s and 30s, and many have public insurance, which tells us something about who is bearing this burden in the healthcare system.

Because our work relies on administrative data and diagnosis codes, it almost certainly captured the “tip of the iceberg”, the cases where someone actually asked about and documented cannabis misuse along with cyclic vomiting syndrome as the presenting condition. Many patients with the same clinical picture are probably still coded as nonspecific vomiting or gastritis and never recognized as CHS at all owing to the failure to take into account substance use during the diagnostic exam.

MedicalResearch.com: What should readers take away from your report?

Response: A few practical points:

• Cannabinoid hyperemesis syndrome is real, and it’s becoming a more routine part of emergency medicine in the U.S.Clinicians should have it on their differential diagnosis when a patient with heavy, long-term cannabis use presents with recurrent vomiting and abdominal pain.
• Asking clearly about cannabis use is essential.Patients may not volunteer cannabis use—especially if they’ve been using it to manage anxiety, sleep, or nausea. A non-judgmental, specific history is critical.
• The pattern matters.Recurrent, cyclic vomiting in a chronic cannabis user, plus relief with very hot showers or baths, should ring loud alarm bells for CHS.
• Cannabis cessation is the key intervention. Supportive care, antiemetics, and in some cases agents like haloperidol or topical capsaicin can help acutely, but symptoms tend to recur if cannabis use continues.
• From a public health standpoint, CHS is an important but still relatively rare complication of cannabis use.Our findings shouldn’t be interpreted as a reason to panic, but they do reinforce that cannabis is not risk-free, especially at higher doses and with long-term, heavy use.

For patients and families, the takeaway is: if someone has repeated unexplained vomiting and uses cannabis regularly, Cannabinoid hyperemesis syndrome should be on the radar, and they should talk honestly with their clinician about their cannabis use.

MedicalResearch.com: What recommendations do you have for future research as a results of this study?

Response: Our study underscores several gaps:

-Who is at risk and why?
We still do not understand why some heavy cannabis users develop Cannabinoid hyperemesis syndrome and others never do. We need more work on genetic, metabolic, and neurobiological risk factors, and on the role of dose, frequency, THC potency, and route of administration (smoked, vaped, edibles, concentrates, etc.).

-Better clinical phenotyping and diagnostic criteria.
Administrative data can only take us so far. Prospective clinical studies that carefully characterize symptoms, timing, co-occurring conditions, and response to cannabis cessation would help refine diagnostic criteria and distinguish CHS from cyclic vomiting syndrome and other causes.

-Treatment and relapse prevention.
We need more rigorous data on what works best in the ED and beyond—pharmacologic options, behavioral interventions to support cannabis cessation, and strategies to prevent relapse both of cannabis use and of CHS symptoms.

-Health equity and policy questions.
With more detailed state-level and health-system data, we could examine how CHS patterns relate to cannabis legalization policies, dispensary density, potency trends, and access to addiction treatment. We also need to understand whether certain racial/ethnic or socioeconomic groups are disproportionately affected or less likely to receive an accurate diagnosis.

MedicalResearch.com: Is there anything else you would like to add?

Response: ICD-10 now includes a recently added and specific diagnostic code for CHS. The availability of this code going forward should provide for more precise public health monitoring of this enigmatic condition. Our study, as with other research conducted over the past 5 to 10 years, had to infer CHS on the basis of the dual presences of a diagnosis of cyclic vomiting syndrome and a cannabis-related disorder.

Disclosures: I do not receive any funding from the cannabis industry or from organizations whose primary mission is to promote or oppose cannabis legalization. My broader research portfolio includes state-funded evaluations of substance use treatment and cannabis policy, but those sponsors had no role in the design, analysis, or reporting of this particular study.

Citation:

Gottlieb M, Shalaby M, Rech MA. The Challenge of Cannabinoid Hyperemesis Syndrome in the Emergency Department. JAMA Netw Open. 2025;8(11):e2545316. doi:10.1001/jamanetworkopen.2025.45316

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Last Updated on November 25, 2025 by Marie Benz MD FAAD