In the quiet chaos of an emergency department, a young patient writhes in pain, clutching their stomach, unable to stop the relentless waves of nausea. They have been here before, seen multiple doctors, and yet the diagnosis remains elusive. For years, these mysterious cases puzzled clinicians, hiding in plain sight among the familiar codes for vomiting, nausea, and gastrointestinal distress. Today, a clearer picture is emerging thanks to researchers at the Jane Addams College of Social Work at the University of Illinois Chicago. They have revealed that cannabinoid hyperemesis syndrome, or CHS, is no longer a hidden phenomenon. Between 2016 and 2022, visits for CHS to emergency departments in the United States rose sharply and remain elevated, illuminating a growing public health concern in an era of expanding cannabis access.
A Syndrome Born From Curiosity
CHS is a condition that challenges expectations. First identified in 2004 in Australia, it remains a syndrome with a mysterious origin. Researchers suggest a tangle of neurophysiological mechanisms may be at play: the downregulation of cannabinoid 1 receptors, altered signaling through transient receptor potential vanilloid 1 channels, and disruptions in hypothalamic thermoregulation. Its symptoms unfold in phases that feel almost story-like: a prodromal phase of subtle abdominal pain or morning nausea lasting months or years; a hyperemetic phase marked by relentless vomiting that sometimes escalates to “scromiting,” where patients scream in pain while vomiting; and a recovery phase, where abstaining from cannabis can eventually bring relief and the promise of normalcy. Amid this turmoil, one coping mechanism appears almost ritualistic—patients often bathe compulsively in hot water for hours, finding temporary solace in warmth.
Yet for clinicians, CHS was long invisible. Patients were frequently tested for a wide variety of conditions, misdiagnosed with cyclic vomiting syndrome, or relegated to vague gastrointestinal labels. It wasn’t until the 2025 update of the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, that a dedicated ICD-10 code, F12.188, allowed CHS to be tracked consistently.
Mapping the Surge
The study, published in JAMA Network Open under the title “Cannabinoid Hyperemesis Syndrome, 2016 to 2022,” used the Nationwide Emergency Department Sample to trace CHS prevalence across the country. The data spanned 993 hospitals across 41 states and the District of Columbia, representing roughly 85 percent of the U.S. population and all of its emergency department visits in 2022.
Survey-weighted analyses revealed that CHS patients were notably younger than other patient groups. The average age of a CHS patient was 30.6 years, while those with cannabis use disorder alone averaged 36.7 years. Those with cyclic vomiting syndrome were slightly older at 37.6 years, and visits without either diagnosis averaged 48.1 years. Among CHS patients, 35.7 percent were aged 18 to 25, and 31.5 percent were 26 to 35, highlighting a concentration among young adults. Gender distribution was nearly even, and regional differences emerged, with the West and Northeast seeing more CHS cases compared with the South. Black patients accounted for 24.7 percent of CHS visits.
Notably, co-occurring use of substances like alcohol, opioids, cocaine, or stimulants was rare, appearing in just over seven percent of CHS visits. This detail underscores that CHS is tightly linked to chronic cannabis use rather than broader substance abuse patterns.
Patterns in the Data
The numbers tell a compelling story. Between 2016 and 2022, emergency department visits for cannabis use disorder increased from 1,008 to 1,465 per 100,000 visits. In contrast, CHS visits surged from 4.36 to 22.33 per 100,000 visits, peaking at 33.06 per 100,000 in the second quarter of 2020. Meanwhile, visits for cyclic vomiting syndrome declined, suggesting a growing clinical awareness and recognition of CHS as a distinct condition.
Younger adults were particularly affected. The probability of a CHS diagnosis among patients previously coded with cyclic vomiting syndrome increased sharply, especially for those aged 18 to 25 and 26 to 35. Quarterly estimates revealed a steady rise in conditional CHS probability after mid-2020, peaking in 2021 at 13.2 percent before tapering slightly to 9.7 percent in 2023, yet remaining well above 2019 levels.
Gender and age influenced risk as well. Female patients had a slightly lower risk relative to males, while patients aged 18 to 25 were more than three times as likely to receive a CHS diagnosis compared with those aged 36 to 50.
From Mystery to Awareness
The study’s authors reflect on a paradox. Despite increased legalization and the availability of high-potency cannabis products, CHS did not show a pronounced increase before 2020. They suggest that underdiagnosis or misclassification may have hidden its true prevalence until broader clinical recognition and heightened diagnostic vigilance brought it into focus.
As cannabis becomes more accessible across the United States, clinicians and public health systems face a growing imperative to recognize and manage CHS effectively. Failure to identify the syndrome can lead to unnecessary diagnostic testing, ineffective treatment, and repeated suffering for patients. Clinical guidelines, decision-support tools, and careful attention to symptom patterns, including severe nausea, vomiting, abdominal pain, and compulsive hot bathing, are critical strategies for improving diagnostic accuracy, particularly among younger adults. The new ICD-10 code, F12.188, provides a pathway for more systematic tracking, but only if clinicians recognize and apply it consistently.
Why This Research Matters
Understanding CHS is more than a statistical exercise. It is a reminder that public health must evolve alongside changing societal behaviors and policies. As cannabis use expands and high-potency products become more common, CHS represents an emerging challenge that intersects with youth health, emergency care, and clinical education. By illuminating who is most affected, how symptoms unfold, and where interventions may be needed, this research equips clinicians and policymakers to respond with greater precision.
In the end, CHS is not simply a syndrome to be coded or counted. It is a lived experience of pain, confusion, and relief for countless young adults across the United States. Bringing clarity to this condition transforms lives, guiding patients from mystery to understanding, from suffering to treatment, and from uncertainty to a future where care can be timely, informed, and compassionate.
More information: James A. Swartz et al, Cannabinoid Hyperemesis Syndrome, 2016 to 2022, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.45310
