Summary: The CDC says a dedicated ICD code introduced on October 1, 2025 largely explains a near-fourfold increase in emergency-department visits labeled as cannabis hyperemesis syndrome (CHS), reflecting improved recognition and coding rather than an abrupt surge. Reported rates rose from about 3.2 per 10,000 before the code to roughly 11–12 per 10,000 afterward. CHS remains likely undercounted in ED data; experts call for standardized criteria and clinician training as legal cannabis use and high-THC products expand.
CDC: New ICD Code Largely Explains Sharp Rise in ER Visits for Cannabis Hyperemesis Syndrome
Atlanta, Georgia, USA - August 28, 2011: Close up of entrance sign for Centers for Disease Control and Prevention. Sign located near the 1700 block of Clifton Road in Atlanta, Georgia, on the Emory University campus. Vertical composition.getty
The recent nearly fourfold rise in emergency-department (ED) visits recorded as cannabis hyperemesis syndrome (CHS) reflects a change in diagnostic coding rather than an abrupt outbreak, the Centers for Disease Control and Prevention (CDC) reports. CHS is a condition of recurrent nausea, vomiting and abdominal pain associated with long-term cannabis use.
What Changed?
Before October 1, 2025, EDs did not have a single, dedicated International Classification of Diseases (ICD) code for CHS and instead documented cases using a mix of broader gastrointestinal and substance-use diagnoses. The CDC adopted a distinct CHS code on October 1, 2025, and recorded CHS-involved ED visits jumped sharply once the code went into effect.
Surveillance Data and Interpretation
Surveillance numbers support the CDC's explanation that the increase reflects improved detection and coding. Reported CHS-involved ED visits were essentially flat for nearly three years before the coding change — 3.19 per 10,000 in January 2023 and 3.35 per 10,000 in September 2025, remaining inside a narrow 2.69 to 3.44 per 10,000 range. Within a month of the code rollout, the rate rose to 11.26 per 10,000 and stayed elevated, averaging nearly 12 per 10,000 through May 2026 — roughly 3.7 times the pre-2025 rate.
“The abrupt, sustained increase might partly reflect improved recognition and coding of CHS rather than a true rise in incidence,” the CDC report states.
Who Is Affected?
The groups with the highest recorded rates remained people aged 15–24 and females. The racial distribution in recorded cases shifted after the new code: Black or African American individuals now have the highest recorded rate, surpassing American Indian or Alaska Native individuals, who topped pre-code counts.
Why Under-Recognition Matters
CHS has likely been undercounted for years because clinicians often misattribute symptoms to other gastrointestinal issues and may not consistently ask detailed questions about cannabis use, frequency, amount or withdrawal. The CDC also notes that ED data capture only patients sick enough to seek emergency care, so the true population incidence is probably higher than ED rates indicate.
Ginger Constantine, M.D., CEO and co-founder of PleoPharma — whose cannabis-withdrawal drug candidate PP-01 is in Phase 3 trials — said the steady pre-code figures probably reflected underdiagnosis linked to inconsistent identification of CHS, cannabis use disorder and withdrawal. She added that a dedicated ICD code helps surveillance but does not replace clinician training and standardized diagnostic criteria.
Legal and Industry Implications
CHS has become an issue in litigation. In Canada, Aurora Cannabis faces a class action from a military veteran alleging failure to warn consumers that its products could cause CHS. In the U.S., a federal class-action lawsuit filed in May accuses Cresco Labs, Green Thumb Industries and Verano of deceptively marketing recreational cannabis as safe while concealing risks including CHS; Verano has denied the allegations.
What Comes Next?
The CDC says the new ICD code improves CHS surveillance and helps estimate public-health impact more accurately. Experts emphasize that additional steps are needed: standardized diagnostic criteria, clinician education on asking about cannabis use and withdrawal, and better treatment options. Improved recognition may both improve patient care and provide a clearer picture of how common CHS truly is as legal access and high-THC products expand.
Estimated burden: about 2.75 million Americans affected by CHS (current estimate cited in the CDC report).
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