Emergency Department Visits for Cannabis Hyperemesis Syndrome Surge in Young Adults: CDC Surveillance 2023-2026
| Audience | Emergency medicine providers, primary care clinicians, public health officials, cannabis users and families, policymakers evaluating cannabis regulation |
| Primary Topic | Epidemiology of cannabis hyperemesis syndrome in emergency departments and implications for clinical practice and public health policy |
| Source | Read the CDC MMWR report |
Emergency Department Visits for Cannabis Hyperemesis Syndrome Surge in Young Adults: CDC Surveillance 2023-2026
A CDC analysis of emergency department diagnoses from January 2023 through May 2026 documents rising rates of cannabis hyperemesis syndrome (CHS)—severe nausea, vomiting, and abdominal pain associated with frequent cannabis use—particularly in young adults aged 15-24. While the apparent surge largely reflects improved diagnosis coding rather than sudden disease emergence, the data highlight an important clinical safety signal warranting patient and provider awareness.
| Data Source | CDC Emergency Department visit data from 13 US states with near-complete data capture |
| Time Period | January 2023-May 2026 (with October 2025 diagnostic code implementation as breakpoint) |
| Key Change | ICD-10-CM diagnostic code R11.2 (cannabis hyperemesis syndrome) implemented October 1, 2025 |
| Pre-Implementation Rate | 3.35 CHS-involved ED visits per 10,000 total ED visits (September 2025) |
| Post-Implementation Rate | 11.26 CHS-involved ED visits per 10,000 total ED visits (October 2025) – 3.4-fold apparent increase |
| Age Pattern | Highest CHS-involved ED visit proportions in ages 15-24 years |
| Sex Pattern | Higher proportion of CHS visits in females compared to males |
| Interpretation | Majority of initial spike reflects improved coding; sustained elevated rates suggest genuine clinical emergence, particularly in youth |
CDC surveillance from January 2023-May 2026 tracked emergency department visits involving cannabis hyperemesis syndrome (CHS). The key finding: when a dedicated ICD-10 diagnostic code (R11.2) was implemented on October 1, 2025, diagnosed CHS cases surged from 3.35 per 10,000 ED visits (September 2025) to 11.26 per 10,000 (October 2025)—a 3.4-fold increase. However, this dramatic jump largely reflects improved diagnostic coding rather than true disease emergence. Post-implementation surveillance (October 2025-May 2026) shows sustained elevated rates, suggesting both genuine clinical recognition and possible underlying epidemiological trends.
Before October 2025, CHS was diagnostically invisible. Patients presenting to the ED with severe vomiting underwent expensive, often unnecessary investigations (imaging, labs, endoscopy) that returned normal. No diagnosis was made. With the new diagnostic code and growing provider awareness, CHS is now recognizable and diagnosable based on clinical history without additional testing. This saves cost, time, and unnecessary procedures. It also enables evidence-based treatment: cessation of cannabis, which is curative.
CHS-involved ED visits are disproportionately common in young adults aged 15-24 years, also with higher proportions in females compared to males. This age-stratified pattern suggests that youth are either using cannabis more frequently, using higher-potency products, or both. It also raises developmental health concerns: adolescent brains are still maturing, and high-potency cannabis exposure during this period carries documented risks beyond CHS, including cognitive and psychiatric effects.
CHS is a relatively newly recognized condition, with clinical case reports first emerging in the 2000s as cannabis potency increased and markets liberalized. It represents one of several cannabis-related conditions increasingly recognized as potency and frequency of use rise globally.
The mechanism of CHS remains incompletely understood. The paradoxical relief with hot bathing or showers suggests involvement of temperature regulation and autonomic nervous system pathways, but cannabinoid mechanisms are not fully elucidated. CB1 receptor abundance in the brainstem and vagal nuclei implicated in vomiting may be relevant.
CHS is distinguished from cannabis withdrawal syndrome (which includes irritability, anxiety, sleep disruption but not typically gastrointestinal symptoms) and cannabis-induced psychosis or anxiety disorders. The gastrointestinal focus of CHS makes it a distinct clinical entity.
Cannabis-legal jurisdictions report higher CHS diagnoses, both pre- and post-coding implementation, compared to prohibition jurisdictions. This geographic variation supports the hypothesis that market access and potency drive CHS incidence, though causation cannot be inferred from surveillance alone.
High-potency cannabis products (concentrates, vapes, edibles) have proliferated in legal markets. Some evidence suggests CHS risk is dose- and frequency-dependent, making high-potency products particularly risky for CHS development. This finding has implications for product regulation and cannabis education.
This surveillance report documents a genuine clinical concern: cannabinoid-induced hyperemesis syndrome is being recognized and diagnosed more frequently, particularly in young adults. While much of the apparent surge reflects improved coding, the underlying trend is real.
Clinically, what matters most is recognition. CHS is simple to diagnose (frequent cannabis use + cyclical nausea/vomiting + normal investigations), completely reversible with cessation, and treatable with supportive care during the acute episode. Providers should know to ask about cannabis when evaluating young patients with refractory nausea and vomiting.
For patients: if you use cannabis frequently and experience cyclical severe nausea and vomiting, discuss CHS with your provider. The condition is not dangerous but is profoundly uncomfortable. Cessation relieves symptoms completely; temporary cessation trial can both diagnose and treat.
For public health: this surveillance supports the argument that high-potency cannabis products carry real risks for certain adverse effects. CHS is not a high-mortality condition, but it’s genuinely symptomatic and dose-related. Product potency regulation deserves consideration, and cannabis education should acknowledge CHS as a real, recognizable, treatable condition rather than dismissing cannabis as harmless.
Interpreting CDC Surveillance Data and Diagnostic Coding Changes
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Six Steps to Understanding CHS Surveillance
Step 1: Understand the Coding Change and Its Impact
On October 1, 2025, the ICD-10-CM coding system implemented R11.2, a dedicated code for cannabis hyperemesis syndrome. Before this date, CHS symptoms were coded as ‘nausea and vomiting, unspecified’ or attributed to gastroenteritis or other conditions. The dedicated code enabled precise diagnosis and tracking. This explains the 3.4-fold apparent increase from September to October 2025—it reflects improved coding, not disease emergence. Always ask: Is an apparent disease increase due to true incidence change or improved diagnostic capture?
Step 2: Separate Coding Artifact from Genuine Epidemiological Change
While much of the initial surge reflects coding changes, the report tracks post-implementation trends (October 2025-May 2026) to assess whether CHS continues at elevated levels or represents a one-time coding adjustment. Sustained elevated rates in the post-implementation period suggest genuine clinical recognition and possible underlying epidemiological change. This distinction—between the coding artifact (September-to-October jump) and genuine post-implementation trends—is critical.
Step 3: Recognize the Limitations of Surveillance Data
This is ED surveillance data. It captures only patients who sought emergency care, not all CHS cases. Severity selection bias occurs: mild CHS cases treated at home with self-care and cessation are not captured. Severe or complicated cases are overrepresented. True population prevalence of CHS would require representative population surveys, not ED data.
Step 4: Examine Stratified Data for Patterns and Hypotheses
Higher CHS-involved ED visit proportions in ages 15-24 and females (vs. males) suggest that demographic factors matter. These patterns support hypotheses (e.g., youth use higher-potency products, or younger patients are more likely to seek care) but do not prove causation. Generate hypotheses from stratified data, then test them with additional research.
Step 5: Connect Surveillance Findings to Mechanistic Understanding
Surveillance shows that CHS exists and is being diagnosed. Mechanistic research (basic science on why cannabis causes hyperemesis, neuroimaging, biomarkers) is needed to understand how and why. Surveillance is observational; mechanism is investigational. Both are necessary for complete understanding.
Step 6: Consider Policy Implications with Appropriate Caution
This surveillance provides evidence that cannabis-related harms are dose-dependent and emerging in youth. That evidence supports policy discussions about potency regulation and youth prevention. However, surveillance data alone do not prove that specific policies (potency caps, age limits, etc.) would reduce CHS. Policy decisions should integrate this evidence with other considerations (personal liberty, market effects, enforcement feasibility, equity implications).
The Same Study Can Mean Different Things Depending on the Question Being Asked
Scientific papers rarely answer a single question. Patients, clinicians, researchers, policymakers, and critics often read the same data differently. The perspectives below explore how this study looks through several evidence-based lenses.
Recognizing and Managing CHS in the Emergency Department
Emergency physicians encounter young patients with severe nausea and vomiting regularly. Before CHS had a diagnostic code and clinical awareness increased, these patients typically underwent extensive, expensive, and ultimately fruitless workup for appendicitis, gastroenteritis, or inflammatory bowel disease. CT imaging, labs, and sometimes endoscopy were ordered. All returned normal. Patients were admitted, treated with antiemetics, and discharged with ‘diagnosis TBD.’
Now, with CHS recognition, the clinical approach changes. When a young patient presents with cyclical severe vomiting and normal investigations, the ED provider should ask: ‘How often are you using cannabis? Are you using concentrates or high-potency products? Do hot baths help?’ If answers support CHS, the diagnosis is made without additional testing. Antiemetic treatment provides acute symptom control, but the critical conversation is about cessation.
From an ED resource perspective, CHS recognition saves costs. Imaging and endoscopy are avoided. Hospital admission may not be necessary if the patient is not severely dehydrated and has reliable access to outpatient follow-up. ED burden related to CHS is manageable if providers know what to look for.
Epidemiology and Population-Level Implications of Rising CHS
This CDC surveillance establishes CHS as a recognizable, quantifiable public health issue emerging in the context of cannabis legalization, potency increases, and youth market access. The age-stratified data showing highest CHS burden in teens and young adults (15-24) is particularly concerning.
From a public health standpoint, this surveillance raises several questions: (1) Does cannabis potency regulation reduce CHS incidence? (2) What cannabis education messages would be most effective in preventing CHS among youth? (3) Are certain cannabis product types (concentrates, high-potency edibles) more likely to cause CHS than others? (4) How do medical vs. recreational legalization frameworks affect CHS epidemiology? These are epidemiological questions warranting surveillance continuation and intervention research.
CHS is not a high-mortality condition, but it represents a genuine adverse effect with population-level implications for youth health. Public health agencies should consider CHS in cannabis surveillance, education, and policy deliberations. The finding that CHS is more prevalent in youth and potentially dose-dependent argues for potency limits and youth-focused prevention strategies.
What Frequent Cannabis Users Should Know About CHS Risk
If you are a frequent cannabis user—particularly of high-potency products like concentrates, high-THC edibles, or vapes—you should know about CHS risk. The condition is not universal (most frequent users do not develop CHS), but risk rises with potency, frequency, and duration of use.
CHS is characterized by cyclical nausea and severe vomiting that develops gradually after prolonged frequent use and is completely relieved by cessation. If you notice a pattern of nausea/vomiting that worsens with continued use and improves when you take breaks from cannabis, CHS may be developing.
The most important thing to know: CHS is completely reversible. Cessation leads to rapid, complete symptom resolution. You do not need medications or hospitalization in most cases; you need to stop or significantly reduce cannabis. If you want to return to cannabis use after CHS resolution, lower-potency products and less frequent use reduce recurrence risk.
From a harm-reduction perspective: be aware of potency. Cannabis concentrates can exceed 90% THC, while flower typically ranges 10-25%. Edibles vary widely. If you use cannabis regularly, monitoring your own physical responses and being willing to reduce if adverse effects emerge is wise.
Cannabis Regulation in Light of CHS Epidemiology
This CDC surveillance provides evidence that cannabis-related harms are emerging and dose-dependent. CHS is more prevalent in jurisdictions with high-potency products and is more common in youth—a vulnerable population. This evidence informs arguments for cannabis potency regulation.
Regulatory approaches in cannabis-legal jurisdictions vary widely. Some states have implemented potency caps (e.g., limiting THC in edibles), while others have not. This surveillance supports the case for potency regulation as a harm-reduction strategy. The question is not whether cannabis is risky (which depends on use pattern and individual vulnerability), but whether unrestricted high-potency products pose greater risk than lower-potency alternatives.
Policy considerations include: (1) potency caps on edibles and concentrates, (2) THC labeling and consumer education requirements, (3) age-restricted marketing and youth access prevention, (4) links between product potency and dosing guidance. Jurisdictions considering cannabis policy should review this surveillance as part of evidence-based regulation.
From an international perspective, cannabis-legal jurisdictions provide natural experiments in potency regulation. Comparing CHS and other adverse-effect epidemiology across jurisdictions with different regulatory frameworks could yield valuable evidence about whether potency limits reduce population-level harms.
What We Don't Know About CHS: Research Priorities
While this surveillance establishes CHS as a recognizable clinical entity, fundamental mechanistic and epidemiological questions remain unanswered. Why do some frequent users develop CHS and others do not? Is there genetic predisposition? Do certain cannabinoid ratios or terpenes matter? What is the mechanism of symptom relief with hot baths?
Research priorities include: (1) case-control studies linking CHS to specific cannabis product characteristics (THC potency, cannabinoid ratios, terpenes); (2) mechanistic research on why hot baths relieve symptoms; (3) neuroimaging or endocannabinoid system biomarkers in CHS patients; (4) pharmacological trials of prevention or treatment strategies; (5) longitudinal studies of CHS incidence and outcomes among frequent users; (6) animal models to test cannabinoid-induced hyperemesis mechanisms.
This CDC report opens research opportunities. The surveillance data identify high-risk populations (youth, frequent users, concentrates/high-potency users), providing sampling frames for mechanistic studies. Collaborations between public health agencies, clinical researchers, and cannabis science could rapidly advance understanding.
CHS as a Marker of Youth Cannabis Risk Exposure
CHS is not primarily a developmental disorder affecting brain maturation, but its high prevalence in ages 15-24 marks this age group as particularly exposed to high-potency cannabis products. This is concerning from a youth health perspective for several reasons.
First, adolescent brains are still maturing, particularly prefrontal regions governing impulse control and reward processing. High-potency cannabis exposure during this developmental window carries documented risks for cognitive impairment, altered brain structure, and psychiatric symptoms. CHS itself is not developmental neurotoxicity, but it marks high-intensity cannabis exposure precisely when the developing brain is most vulnerable.
Second, CHS prevalence in teens and young adults suggests high market access to high-potency products among youth. This is a regulatory and prevention challenge. Youth-focused cannabis education should address both CHS as an acute, reversible consequence and longer-term developmental risks from high-potency cannabis during adolescence.
Third, from a clinician perspective, a teen presenting with CHS offers an opportunity for counseling about cannabis risks. The conversation might be: ‘You’ve developed CHS because of frequent, high-potency cannabis use. This will go away if you stop. But I’m also concerned that frequent cannabis use at your age carries risks for cognition and mental health. Let’s talk about reducing or stopping entirely.’
CHS Epidemiology and Disparities in Cannabis Access and Harm
This CDC surveillance does not report detailed demographic breakdowns beyond age and sex, but cannabis-related harms are not evenly distributed across populations. Cannabis legalization and high-potency product markets are unevenly available geographically and demographically. Understanding who develops CHS in which contexts is important for equitable public health response.
Cannabis legalization in the US has been geographically uneven, with relatively rapid legalization in certain regions (west coast, parts of northeast) while other regions remain prohibition-focused. This creates potential disparities in CHS epidemiology: youth in legal markets with access to high-potency products may face higher CHS risk than youth in prohibition regions, but data gaps make this hypothesis difficult to test.
From an equity perspective, public health responses to CHS should be designed with attention to populations most burdened. If CHS is more prevalent in specific geographic regions, youth of specific racial/ethnic groups, or socioeconomic contexts, targeted education and clinical training in those communities is warranted.
Additionally, if cannabis potency regulation is adopted as a harm-reduction strategy, such regulation should include attention to equity. For example, are potency limits enforced equitably across licensed and illicit markets? Do price controls on lower-potency products ensure affordability? Regulation without equity attention can worsen disparities.
Training the Next Generation of Clinicians to Recognize and Manage CHS
This surveillance and rising CHS prevalence have implications for medical and nursing education. Historically, CHS received minimal attention in curricula. Trainees in emergency medicine, primary care, gastroenterology, and psychiatry may have no formal education on CHS recognition or management.
Incorporating CHS into clinical training would improve recognition and reduce unnecessary investigation. Key teaching points: (1) CHS is cannabis-use-dependent; (2) normal investigations are expected in CHS; (3) cessation is curative; (4) the hot-bath phenomenon is a diagnostic clue; (5) age 15-24 and high-potency cannabis use are risk factors.
From a medical education perspective, CHS also exemplifies an important broader principle: drug-related adverse effects evolve with market changes. As cannabis markets mature and potency increases, new adverse effects emerge and become diagnosable. Trainees should be taught to recognize evolving adverse-effect epidemiology and adjust clinical practice accordingly.
Continuing education for practicing clinicians is also important. ED physicians, hospitalists, primary care providers, and gastroenterologists should all be aware of CHS. Professional society guidelines (American College of Emergency Physicians, American Gastroenterological Association) could include CHS recognition and management.
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Frequently Asked Questions
What is cannabis hyperemesis syndrome and how is it diagnosed?
Cannabis hyperemesis syndrome (CHS) is a condition characterized by cyclical nausea, severe vomiting, and intense abdominal pain that develops after prolonged, frequent cannabis use and resolves completely with cannabis cessation. There is no specific laboratory test; diagnosis is clinical: (1) history of frequent, prolonged cannabis use; (2) cyclical episodes of severe nausea and vomiting; (3) normal or non-specific findings on abdominal imaging, endoscopy, and laboratory investigations. A key diagnostic clue is temporary relief with hot baths or showers, a paradoxical response unique to CHS.
Why did CHS diagnoses jump so dramatically in October 2025?
On October 1, 2025, the ICD-10-CM diagnostic coding system implemented a dedicated code for CHS (R11.2), replacing nonspecific codes for nausea and vomiting. This enabled ED providers to diagnose and code CHS precisely rather than attributing symptoms to other conditions. The 3.4-fold increase from September to October 2025 largely reflects this coding change, not a sudden epidemiological surge. However, sustained elevated rates from October 2025-May 2026 suggest genuine clinical recognition and possible underlying incidence increase.
Who is at risk for CHS?
CHS develops almost exclusively after prolonged, frequent cannabis use (typically months to years of daily or near-daily use). It is not a risk for occasional users. Risk appears highest in individuals with high cumulative THC exposure, raising the hypothesis that potency and frequency are key risk factors. Age groups 15-24 show the highest CHS-involved ED visit proportions in this surveillance, suggesting youth may be particularly vulnerable or more likely to use high-potency products.
Why do hot baths relieve CHS symptoms?
The mechanism is unknown. CHS patients often report profound, dramatic relief with hot baths or showers, a response so characteristic it has become a diagnostic clue. Possible mechanisms include modulation of autonomic nervous system tone, effects on temperature regulation centers, or unknown cannabinoid receptor-mediated pathways. The mechanism remains an open research question.
Is CHS dangerous? Does it cause permanent harm?
CHS itself is not life-threatening, but severe vomiting can lead to dehydration, electrolyte imbalances, and rarely, serious complications like esophageal rupture. More commonly, CHS causes profound discomfort, lost work/school time, and anxiety about the cause. The critical point: CHS is completely reversible with cannabis cessation. There is no permanent organ damage or chronic sequelae if cannabis use is discontinued.
How is CHS treated?
Cessation of cannabis use is the definitive treatment and leads to complete resolution of symptoms, typically within days. Supportive care during acute episodes includes antiemetic medications (ondansetron, metoclopramide), IV hydration if needed, and symptomatic relief. Some patients use hot baths for temporary relief. Unlike other cannabis withdrawal effects (irritability, sleep disruption), CHS typically resolves rapidly once cannabis is stopped.
Does cannabis potency matter for CHS risk?
This surveillance does not analyze potency directly, but CHS incidence is higher in cannabis-legal jurisdictions where high-potency products are available and prevalent. This supports the hypothesis that high-THC products increase CHS risk. Some clinical evidence suggests CHS is dose- and frequency-dependent. This raises the question of whether cannabis product potency regulation might reduce CHS incidence, though direct evidence requires intervention studies.
Can you get CHS from low-THC or CBD-dominant cannabis?
CHS is specifically associated with THC and high-frequency THC use. Low-THC or CBD-dominant products have not been reported as CHS triggers in the literature. However, any cannabis use involves some THC exposure, and long-term high-frequency use of even lower-THC products theoretically carries some CHS risk. This remains an area for future research.
How common is CHS? How many people have it?
True population prevalence of CHS is unknown; this surveillance captures only ED visits. Pre-coding, CHS was likely significantly undercounted. Post-coding, CHS accounted for ~11 per 10,000 ED visits by May 2026, but this represents only patients seeking ED care, not all CHS cases. Population surveys would be needed to estimate true prevalence among cannabis users or the general population.
What should I do if I think I have CHS?
First, discuss with your healthcare provider. Bring up cannabis use history and describe your symptoms (cyclical nausea/vomiting pattern, relation to cannabis use, relief with hot baths). Your provider can review investigations to rule out other causes and consider CHS. Most importantly, discuss cessation or significant reduction of cannabis use as the primary treatment. If cessation leads to rapid symptom resolution, CHS is confirmed. If CHS is your diagnosis and you want to return to cannabis use in the future, discuss lower potency, lower frequency use with your provider.
