A newly recognized syndrome is causing cycles of severe vomiting in long-term cannabis users. Credit: Stock

Hospitals are seeing a striking rise in people with sudden bouts of intense vomiting linked to long-term cannabis use, a condition now formally classified as cannabis hyperemesis syndrome.

With the new medical code, doctors and researchers can better track how often it occurs and how it develops. Many patients are surprised to learn cannabis may be triggering their symptoms, especially since it is commonly used to ease nausea.

Rising ER Visits Linked to Chronic Cannabis Use

Over the past ten years, emergency departments have treated a growing number of people seeking help for abdominal pain accompanied by severe or persistent vomiting. A shared characteristic among many of these patients is long-term cannabis use.

Clinicians only recently gained a standardized way to document this issue. Last month, a diagnostic code for “cannabis hyperemesis syndrome” became available, describing a gastrointestinal condition that begins within 24 hours of the most recent use and can continue for several days. People who develop the syndrome often face three or four bouts of symptoms each year.

New Diagnostic Code Creates Clarity for Providers

On October 1, the World Health Organization added the new code, R11.16, to its International Classification of Diseases manual (ICD-10, currently). The Centers for Disease Control and Prevention also incorporated the update for U.S. health care providers.

The change offers several practical benefits. With a single, specific billing code, clinicians no longer need to rely on multiple less accurate codes to describe the condition. The new entry also allows providers to recognize repeat episodes more easily by checking a patient’s medical records.

For researchers, the update is especially valuable. It provides a clearer picture of how often the condition appears and who is most affected, helping investigators such as Beatriz Carlini track trends that were previously hard to pinpoint.

“It helps us count and monitor these cases,” said Carlini, a research associate professor at the University of Washington School of Medicine who studies adverse health effects of cannabis use. “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 Can Delay Diagnosis

Although cases are increasing, many clinicians remain unfamiliar with the syndrome because it is still relatively new in medical practice.

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

Even with a proper diagnosis, patients are sometimes reluctant to accept that cannabis is causing their symptoms, said Dr. Chris Buresh, an emergency medicine specialist with UW Medicine and Seattle Children’s. Cannabis is widely used to reduce nausea for chemotherapy patients or those managing HIV or migraines, which makes the connection more difficult for some to understand.

“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 Difficult Treatment Options

What causes the condition to affect some individuals 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.

The syndrome is also challenging to treat. Standard anti-nausea medications often do not work well, he said, leading physicians to try second- or third-line options such as Haldol, which is usually prescribed for psychotic episodes.

Some patients find temporary relief from capsaicin cream, an over-the-counter product that creates a warming sensation. Others report that hot showers ease their discomfort.

“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 a patient’s recovery. Because the syndrome appears intermittently, some cannabis users may believe a recent episode was unrelated and continue using cannabis without problems until they suddenly become very sick again. For those who accept the diagnosis and try to stop using cannabis to improve their symptoms, addiction can make that process challenging, Carlini said.

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