A new diagnostic code, not a sudden outbreak, is behind a nearly fourfold spike in emergency-room visits for cannabis hyperemesis syndrome, with the Centers for Disease Control and Prevention highlighting that the condition has long been underestimated.

Emergency departments (EDs) had no dedicated code for cannabis hyperemesis syndrome (CHS), a condition marked by cycles of nausea, vomiting, and abdominal pain tied to long-term cannabis use. They used to rely instead on a combination of broader diagnosis codes.

That changed on October 1, 2025, when the CDC introduced a specific code for CHS. Since then, cases recorded in emergency rooms spiked, but the CDC says this is likely due to the new code catching cases that were always occurring, rather than a genuine surge in the condition itself.

With an estimated 2.75 million Americans affected by CHS, recognizing the condition in EDs is increasingly important, particularly as legal cannabis becomes more widely available and high-THC products are sought out by many consumers.

The data seem to back up the CDC's explanation. CHS-involved ED visits barely moved for nearly three years before the new code took effect, 3.19 per 10,000 in January 2023, 3.35 by September 2025, never straying outside a narrow 2.69-to-3.44 band. But within a month of the code's rollout, CHS-related ED visits jumped to 11.26 per 10,000, and stayed elevated, averaging nearly 12 per 10,000 through May 2026, about 3.7 times the pre-2025 rate.

The CDC attributed the trend, at least in part, to improved clinical recognition and coding of CHS, rather than to a true and immediate increase in the condition’s incidence.

“The abrupt, sustained increase might partly reflect improved recognition and coding of CHS rather than a true rise in incidence,” the report reads.

The new code didn't change who was most at risk. People aged 15–24 and females remained the top groups, as before. However, it did shift the racial breakdown, as Black or African American individuals now have the highest rate, edging out American Indian or Alaska Native individuals, who topped the list before the code's introduction.

The Impact Of Cannabis Hyperemesis Syndrome On Patients And Businesses

Limited recognition of CHS is affecting both patients and businesses. In emergency rooms, the condition is often mistaken for other stomach illnesses, feeding into years of underestimating its true toll.

Ginger Constantine, M.D., CEO and co-founder of PleoPharma, whose cannabis-withdrawal drug candidate PP-01 is in Phase 3 trials, explained that the steady case numbers likely reflect undercounting, driven by the under-recognition of CHS, cannabis use disorder and withdrawal. Providers often fail to ask detailed questions about cannabis use, including frequency, amount and withdrawal symptoms, while the lack of standardized criteria makes the condition harder to identify consistently.

“That gap made consistent recognition, and by extension consistent coding, much harder to achieve,” she said. “A dedicated ICD [International Classification of Diseases] code is an important step, but it doesn't resolve the underlying gap. Providers still need training and tools to ask the right questions from the start.”

In the report, the CDC acknowledged that ED data only capture patients sick enough to seek emergency care, and, therefore, the true incidence of CHS is likely underestimated. Still, the agency said the new code "has improved CHS surveillance and estimation of public health impact."

Constantine further explained that the lack of treatments for cannabis-related conditions can contribute to missed diagnoses in emergency departments, where patients with vomiting and abdominal pain are often treated for gastrointestinal issues before cannabis use is considered. She added that a potential treatment for cannabis-related conditions could encourage clinicians to ask about cannabis use and help patients disclose related complications.

CHS, however, is also becoming a legal liability. In Canada, Aurora Cannabis faces a class action from a military veteran who alleges the company failed to warn consumers that the condition could develop from its products. In the U.S., a class-action federal 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.