A new ICD code designed to help doctors identify cases of cannabis hyperemesis syndrome more consistently now gives researchers a clearer picture of how often the diagnosis – linked to chronic cannabis use – occurs.

Increasingly linked to recurring bouts of vomiting, patients often resist the diagnosis, and the condition’s causes remain murky, according to a study by the University of Washington School of Medicine.

Relief can come from unusual sources like hot showers or capsaicin cream.

Over the last decade, emergency departments have seen a steady rise in patients seeking help for abdominal pain and episodes of intense or long-lasting vomiting.

Until last month, clinicians lacked a standardized way to document this condition.

Now, there is a diagnostic code for “cannabis hyperemesis syndrome,” a gastrointestinal disorder that begins within 24 hours of the most recent cannabis use and can continue for several days.

People who experience it typically face these symptoms three or four times each year.

In October, the World Health Organization added a formal entry for the condition to its International Classification of Diseases manual (ICD-10, currently).

The Centers for Disease Control and Prevention also incorporated the new code, R11.16, into U.S. diagnostic systems.

Clinicians can now document the syndrome with a single, specific billing code instead of relying on multiple, less precise ones.

The code also helps providers recognize repeat episodes during future visits.

“It helps us count and monitor these cases,” said Beatriz Carlini, a research associate professor at the University of Washington School of Medicine. “In studying addiction and other public health concerns, we have three sources of data: what clinicians tell us, what people in the communities tell us, and what health records tell us. A new code for cannabis hyperemesis syndrome will supply important hard evidence on cannabis-adverse events, which physicians tell us is a growing problem.”

Limited Awareness Contributes to Delayed Diagnosis

Although hospitals are seeing more patients with these symptoms, many providers are still unfamiliar with the condition because it has only recently been defined, researchers said.

“A person often will have multiple [emergency department] visits until it is correctly recognized, costing thousands of dollars each time,” Carlini said.

Even after an accurate diagnosis, some patients struggle to accept that cannabis is the source of their severe nausea and vomiting, said Dr. Chris Buresh, an emergency medicine specialist with UW Medicine and Seattle Children’s.

Cannabis is widely known for easing nausea in people undergoing chemotherapy or living with chronic conditions such as HIV and migraines, which adds to the confusion.

“Some people say they’ve used cannabis without a problem for decades. Or they smoke pot because they think it treats their nausea,” he said. “It seems like there’s a threshold when people can become vulnerable to this condition, and that threshold is different for everyone. Even using in small amounts can make these people start throwing up.”

Uncertain Causes and Challenging Treatment

Why the syndrome affects some cannabis users but not others remains unclear.

“We don’t know if it’s related to the greater general availability of cannabis or the higher THC potency of some products or something else,” Buresh said.

Treating the condition is difficult. Standard anti-nausea medications often do not work reliably, he said, which sometimes forces clinicians to turn to second and third-line options such as Haldol, a medication more commonly used for psychotic episodes.

Some individuals find limited relief through capsaicin cream, an over-the-counter analgesic that creates a warming sensation. According to Buresh, some patients apply it to their abdomen during episodes. Hot showers are also widely reported as helpful.

“That’s something that can clinch the diagnosis for me, when someone says they’re better with a hot shower. Patients describe going through all the hot water in their house,” he said.

Why Recovery Can Be Difficult

Several factors can slow recovery.

Because the syndrome appears intermittently, some cannabis users may assume a recent episode was unrelated and continue using the substance without immediate problems, only to suddenly become severely ill again.

For those who accept the diagnosis and try to stop cannabis use to ease their symptoms, addiction can make abstinence difficult, Carlini said.

University of Washington School of Medicine. (2025, November 27). Why more cannabis users are landing in the ER with severe vomiting. ScienceDaily. Retrieved December 5, 2025 from www.sciencedaily.com/releases/2025/11/251126095029.htm