Emergency department visits involving cannabis hyperemesis syndrome, a condition that causes severe nausea, vomiting and abdominal pain, have increased sharply in the United States, with the highest rates reported among younger people, according to a new Centers for Disease Control and Prevention report.
CDC researchers found the proportion of emergency department visits involving cannabis hyperemesis syndrome, or CHS, increased from 3.35 per 10,000 visits in September 2025 to 11.26 per 10,000 in October 2025. Overall, CHS-involved emergency visits increased 16% from October 2025 through May 2026.
Researchers caution that much of the increase may be tied to a change in how the condition is identified.
A specific diagnosis code for CHS was introduced in October 2025. Before then, researchers said many cases may have been misclassified as cyclic vomiting syndrome or recorded under other cannabis-related diagnoses.
“The introduction of a specific diagnosis code for CHS in October 2025 represents an important advancement for public health surveillance,” researchers wrote.
The highest proportions of CHS-related emergency visits were females ages 15 to 24.
CHS is typically associated with heavy, frequent and long-term cannabis use. However, researchers said emerging evidence suggests symptoms can develop much sooner than previously thought, including within the first year of cannabis use.
In addition to the new coding, researchers said the higher rates among younger people could also reflect changes in cannabis use, including earlier initiation, more frequent use, increased use of high-potency THC products and methods such as vaping and dabbing. Researchers also cited changing perceptions of the risks associated with marijuana.
The CDC also cautioned that its data likely underestimate the true number of CHS cases because they only include people whose symptoms were severe enough to require emergency care. Identifying CHS also depends partly on patients reporting their cannabis use, which researchers said likely doesn’t always happen.
In addition to the recent spike, suspected CHS cases also increased substantially between 2016 and 2022, with the largest increase occurring during the COVID-19 pandemic. Researchers noted that the increase coincided with widespread state-level cannabis legalization, although marijuana remains illegal under federal law.
CHS symptoms can be severe and debilitating. Symptoms may resolve after a person stops using cannabis, although researchers noted that rare cases have even resulted in death.
The findings come as marijuana use continues to rise nationwide.
For the first time, more Americans report using marijuana daily or nearly daily than drinking alcohol or smoking cigarettes, according to recently released data from the Substance Abuse and Mental Health Services Administration.
About 21.4 million Americans ages 12 and older reported using marijuana daily in 2025, compared with 17.2 million who reported drinking alcohol every day or most days and 19.9 million who regularly smoked cigarettes.
