Cannabinoid hyperemesis syndrome (CHS), that paradoxical condition where cannabis triggers nausea instead of relieving it, is back at the center of public health debate. This time, it’s for two major reasons: a massive new study published in JAMA Network Open and the recent decision by the World Health Organization to assign CHS its own diagnostic code.
Together, these developments paint a clearer (if more complex) picture of why this gastrointestinal syndrome is showing up more often in emergency departments, especially among younger adults and heavy users of high-potency cannabis products.
CHS by the numbers: Who ends up in ER and why
The study, conducted by the University of Illinois, analyzed more than 188 million emergency room visits between 2016 and 2022 and found a consistent trend: cases compatible with CHS surged during the pandemic and never returned to pre-COVID levels.
According to the analysis, CHS cases rose from 4.4 per 100,000 visits to a peak of 33.1 in the second quarter of 2020, then stabilized around 22.3 by the end of 2022. In other words, ER visits compatible with CHS became roughly seven times more common over the study period.
Also read: Is Cannabinoid Hyperemesis Syndrome Real? If So, Should It Be on Warning Labels?
Researchers attribute part of the rise to the effects of the pandemic. As the authors explained: “The COVID-19 pandemic likely catalyzed the rise in CHS through stress, isolation, and increased cannabis use. After peaking in 2021, CHS incidence declined but plateaued above prepandemic levels”, according to Hemp Gazette.
Key data points from the study:
- Highest concentration among adults 18–25 years old (35.7%) and 26–35 (31.5%)
- Simultaneous decline in non-cannabis cyclic vomiting diagnoses
- Parallel rise in cannabis-related diagnostic codes
- More prevalent in the Northeast and West of the U.S. than in the South
The authors also highlight a major limitation: because CHS did not yet have its own ICD-10 code during the study period, clinicians had to infer cases by combining vomiting-related codes with secondary cannabis diagnoses, leaving room for misclassification or underdiagnosis.
From “scromiting” to official recognition: WHO adds CHS to ICD-10
This syndrome has been nicknamed “scromiting” (that is, a blend of screaming and vomiting) to describe the intense heaving episodes and severe abdominal pain that some patients experience.
While ER data shows a sustained increase, the World Health Organization took a landmark step on October 1, 2025, adding CHS to the International Classification of Diseases under the diagnostic code R11.16. That might sound bureaucratic, but it’s a big deal: once a condition has its own code, hospitals, insurers, and public-health agencies can actually count it, track trends, and fund research around it.
As reported by researchers at the University of Washington: “Since October 1, the World Health Organization’s International Classification of Diseases manual […] incorporated a diagnostic code specific to this condition, making it easier for physicians around the world to identify and track it”, as Las Drogas Info shared.
This change helps harmonize criteria, improve epidemiological monitoring, and reduce the number of patients who cycle through emergency rooms without a proper diagnosis, something that happens too often.
UW Medicine researcher Beatriz Carlini emphasized: “A person often will have multiple [emergency department] visits until it is correctly recognized, costing thousands of dollars each time”.
Another challenge is disbelief. Many patients initially reject the idea that cannabis—a plant widely used for easing nausea—could be the cause of their symptoms. As clinicians note: “Some people say they’ve used cannabis without a problem for decades. Or they smoke pot because they think it treats their nausea”.
High potency, high frequency: When weed stops playing nice
Although there is no definitive explanation yet, current scientific literature points to a combination of chronic use, high-potency THC products, and individual susceptibility. These factors may disrupt mechanisms such as CB1 receptor regulation, TRPV1 signaling, or hypothalamic thermoregulation. In plain English, the systems that help manage pain, temperature, and nausea.
Several behaviors help clinicians identify CHS quickly:
- cyclical episodes of intense nausea and vomiting
- compulsive hot showers for relief
- repeated cannabis use despite worsening symptoms
As Dr. Chris Buresh from UW Medicine explained: “It seems like there’s a threshold when people can become vulnerable to this condition, and that threshold is different for everyone. Even using in small amounts can make these people start throwing up”.
Treatment, management, and clinical challenges
Traditional anti-nausea medications are not particularly effective for CHS. Instead, some physicians are turning to drugs like haloperidol or topical capsaicin, which activate the same heat-sensing pathways that make hot showers so relieving.
In the meantime, the JAMA study underscores the need for better clinical training: “The findings highlight the need for continued vigilance and refinements to the clinical recognition of CHS”.
In a world where legal and medical cannabis are part of daily life for millions, the emergence of CHS shouldn’t be used as a weapon for stigma. Instead, it’s an opportunity to strengthen education, harm-reduction strategies, and clinical awareness.
Because understanding how each body responds to cannabis—and what happens when that balance shifts—is essential to building more informed, safer, and healthier relationships with the plant.
