US sees a big jump in nausea cases among frequent marijuana users in the hospital

NEW YORK (AP) — In the past year, the U.S. has seen a jump in frequent marijuana users going to the hospital with a nausea and vomiting condition, according to a report released Thursday.

“The abruptness and sustained magnitude of the increase” is largely due to the condition getting its own diagnosis code last fall, which is providing a more accurate picture of what was an underrecognized problem, the authors of the U.S. Centers for Disease Control and Prevention report wrote.

Hospital emergency room diagnoses of the condition, cannabis hyperemesis syndrome, rose 16% from last October to May of this year, federal researchers found.

The syndrome — seen in people who frequently use marijuana, especially smokers — is characterized by recurring nausea, uncontrollable vomiting and excruciating abdominal pain.

Past research has suggested that an estimated 2.75 million Americans suffer from it each year, and that hospital emergency room visits have been rising as daily recreational marijuana use has increased.

But experts also have said that the syndrome probably has been underdiagnosed, possibly because doctors may not have understood patients' marijuana use or because they attributed the suffering to a different illness.

Tracking the syndrome depended on combining diagnostic codes for nausea and vomiting, and for cannabis use. But last October, a new code was introduced to streamline the diagnosis.

In the new paper, researchers at the CDC's National Center for Injury Prevention and Control looked at emergency room data from about 7,500 healthcare facilities across the country through May. From January 2023 through the summer of 2025, almost 200,000 syndrome-related visits were made to the emergency departments.

The burden on ERs was relatively flat over most of the study period. But then it jumped in October, when the new code went into effect.

The largest increases were seen in people aged 15 to 24, in teenage girls and women, and in Black Americans and in American Indian and Alaska Natives.

The increase in younger people diagnosed with the syndrome “was actually one of the surprising findings for us,” said CDC's Alana Vivolo-Kantor, the study's first author.

“Because the assumption going in was, ‘well, how can they have chronic use?’” she said. “How early were they using cannabis?”

The findings suggest a need to raise awareness about the syndrome, particularly in teens and young adults. The report also suggests a need for more research, including into how newer high-potency THC and hemp-derived products — some of which come in the form of vapes, drinks and gummies — are being used by, and affecting, younger Americans, she said.