Emergency department (ED) visits related to cannabinoid hyperemesis syndrome (CHS), characterized by recurrent nausea and vomiting in chronic cannabis users, have steadily increased amid legalization, expanding formulations, and higher-potency products. The trend is placing pressure on clinicians to recognize and accurately diagnose the condition.
“CHS now accounts for a growing share of emesis-related ED presentations,” reported James A. Swartz, PhD, of the University of Illinois, Chicago, and colleagues in one of the latest studies documenting the increasing prevalence.
“Given frequent misdiagnosis and costly, unnecessary testing, greater clinical awareness is needed,” they wrote.
CHS is a subtype of cyclical vomiting syndrome (CVS) that, as detailed in Rome IV criteria, presents with recurrent severe nausea, vomiting and abdominal pain, with the defining feature of chronic cannabis use. Although patients with CHS may report compulsive, prolonged hot bathing, such behavior is also observed in CVS.
Rising Prevalence
Recent epidemiologic data suggest that increasing CHS prevalence corresponds with the legalization of recreational cannabis across the US over the past 15 years, with notable upswings during the COVID pandemic and persistently elevated rates thereafter.
In their cross-sectional analysis of data from the Nationwide Emergency Department Sample, Swartz and colleagues observed that CHS prevalence increased from 4.4 reports per 100,000 visits in 2016 to 33.1 per 100,000 visits in the second quarter of 2020, with rates remaining elevated at 22.3 per 100,000 visits in 2022.
Notably, the study also showed a marked decline in CVS-only diagnoses, from 300 to 186 cases per 100,000 visits over the same period. This inverse trend may reflect improvement in diagnostic differentiation between CVS and CHS.
“The decline in CVS-only cases shown in our paper supports the notion that a portion of cases previously diagnosed as CVS with no clear underlying cause are now being correctly attributed to cannabis use,” Swartz told Medscape Medical News.
In the analysis, CVS cases with likely causes other than CHS were excluded, he noted.
Additional studies published in the past year have similarly documented rising CHS rates in Massachusetts, Northern California, and elsewhere in the US.
Although most studies show the highest CHS rates among young adults in their twenties and thirties, the demographic group most closely associated with cannabis use, CHS is increasing being reported in adolescents.
In a nationwide retrospective analysis of adolescents aged 13-21 years, researchers observed a 49% increase in CHS-related ED visits between 2016 and 2023, rising from 160.4 cases per 1 million ED visits in 2016 to as many as 1968 in 2023.
Importantly, although CHS-related ED visits were more common in states with legalized recreational cannabis than in nonlegalized states (1909 vs 834 per million), the rate of increase was actually higher in states without legalization (49.3% vs 32.5%).
Possible Contributing Factors
The increasing range of higher-potency cannabis products (eg, vapes, tinctures, and edibles) appear to be a key contributor to CHS risk, explained Michael Shalaby, MD, an assistant professor of emergency medicine with the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, whose team has also published research on CVS and CHS.
“Many chronic cannabis users, defined as use for 4 days or more per week, are not traditional smokers anymore, [and] potency is certainly a causative factor,” Shalaby told Medscape Medical News.
“One can only smoke so much cannabis before becoming altered, which is a natural stop-point for ingestion,” he explained. “However, even a single drink can contain hundreds to thousands of mg of THC [tetrahydrocannabinol].”
“Combine this with chronic use, and we are seeing worse and more frequent cases of CHS.”
Still, CHS appears to affect only a small percentage of overall cannabis users, Swartz noted.
“If we could subset cannabis users to those who use the more potent products and those who use them more frequently and for an extended time, we could get a better idea of risk for CHS among this sub-population of high-risk cannabis users,” he said.
The specific etiology of CHS is unclear. Proposed mechanisms include downregulation of high cannabinoid 1 receptors, disrupted hypothalamic thermoregulation, or even possible genetic susceptibility, Swartz said.
What is clear, Shalaby added, is the upswing in cases and the frequency with which CHS is missed.
“We are definitely seeing a lot more frequent cases of CHS,” he said. “However, they are frequently missed because emergency physicians often either forget to ask about social history and drug use or do not correlate symptoms of nausea and vomiting with cannabis use.”
Treatment Challenges
Although cannabis cessation remains the standard recommendation in CHS management, there are currently no treatments approved by the FDA for the condition.
Ondansetron is the most commonly used antiemetic in CHS, however, Shalaby said the data do not support it being the most effective, and when used alone it is often insufficient.
Instead, “a combination of antipsychotic medications such as droperidol or haloperidol, benzodiazepines such as lorazepam or diazepam, and analgesics such as ketorolac, make for the most effective combination of medications to treat CHS,” he said.
The medications address not just nausea but also retching and abdominal pain, the hallmarks of CHS as well as CVS, Shalaby added.
Studies supporting this approach include the randomized Haloperidol vs Ondansetron for Cannabis Hyperemesis Syndrome trial, which demonstrated the superiority of haloperidol over ondansetron for CHS, with improvements in nausea, reduced pain, and shorter ED stays.
On a more anecdotal level, Shalaby and his team have also reported success with regional anesthesia in CHS that is refractory to treatment. They administered anesthesia via a thoracic erector spinae plane block, a technique previously used for other conditions of gastric neurodysmotility accompanied by intractable vomiting.
“We have only performed this block on this patient [in the case study], but given how efficacious it was for her as well as for other disorders of gut-brain interaction, such as gastroparesis, or sources of visceral pain [gastritis, gastrointestinal malignancy, etc.], we would offer it to any patient with refractory pain,” Shalaby said.
Such novel treatments “are viable options for patients with intractable symptoms,” he added. “This can be the difference between intractable symptoms and complete relief, and between admission and discharge.”
Richard J. Gawel, MD, first author on the case reporting describing the use of a thoracic erector spinae plane block and an emergency physician at the Hospital of the University of Pennsylvania, noted that symptom improvement typically occurred within 20-30 minutes, “consistent with the onset of the medication we administer when doing the block.”
Gawel said his group probably performs such blocks for this indication of any ED. He and his research team are currently conducting larger studies to further assess the effectiveness of this approach.
For clinicians, the take-home message is the need to do a better job at recognizing CHS, Shalaby concluded.
“Any patient with intractable vomiting and abdominal pain should have a social history taken,” he said. “And any patient who uses cannabis for at least 4 days a week should be suspected of having CHS.”
Swartz, Shalaby, and Gawel had no disclosures to report.
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