A cannabis-related syndrome that can cause severe nausea, repeated vomiting and intense abdominal pain is being diagnosed more frequently in U.S. emergency rooms, with the sharpest increase reported among teenagers and young adults. According to a report by the U.S. Centers for Disease Control and Prevention, emergency department diagnoses of cannabis hyperemesis syndrome, or CHS, rose 16% between October 2025 and May 2026.
The syndrome presents a medical paradox: Cannabis is sometimes used to relieve nausea, yet chronic use can eventually produce the opposite effect. “This is a paradoxical phenomenon: Although cannabis is sometimes used to treat nausea, chronic use can cause a syndrome characterized by nausea, repeated vomiting and abdominal pain,” said Dr. Nadav Ilani, a gastroenterology specialist with Clalit Health Services.
Ilani cautioned that the increase in reports does not necessarily mean the syndrome itself has become more common. “The rise in reports does not necessarily indicate an increase in the incidence of the syndrome, but likely reflects improved diagnosis and reporting following the introduction of a dedicated diagnostic code into computerized medical systems,” he said.
One of the most striking findings was that much of the increase was recorded among people ages 15 to 24. The figure surprised CDC researchers because CHS usually develops only after years of chronic cannabis use, raising questions about how young some patients may have been when they began using marijuana regularly.
Researchers examined emergency department data from about 7,500 medical facilities across the United States. From January 2023 through the summer of 2025, nearly 200,000 visits related to the syndrome were recorded. Rates remained relatively stable during most of the study period but rose after the new diagnostic code was introduced.
Previous studies have estimated that about 2.75 million Americans experience the syndrome each year and that emergency department visits have increased alongside rising rates of daily recreational marijuana use. The largest increases were reported among girls and women, Black Americans, Native Americans and Alaska Natives.
What is cannabis hyperemesis syndrome?
Cannabis hyperemesis syndrome, or CHS, occurs among frequent marijuana users, particularly those who smoke it regularly.
According to medical information from Cedars-Sinai, the syndrome typically develops after 10 to 12 years of chronic use and is most common among people who use marijuana every day. Only a small proportion of regular users, however, develop the condition.
THC and similar substances in marijuana bind to receptors in the brain that produce the drug’s “high” and other effects. Similar receptors are also found in the gastrointestinal system. As a result, marijuana can affect how quickly the stomach empties and influence the esophageal sphincter, the ring-shaped muscle that opens and closes to allow food to pass from the esophagus into the stomach.
Dr. Nadav Ilani“The exact cause of the syndrome is still being investigated, but the leading scientific theory is that chronic use causes prolonged overstimulation of the endocannabinoid system,” Ilani said. “This overstimulation disrupts the natural control mechanisms of the digestive system and brain and produces a paradoxical, opposite effect. While cannabis generally helps suppress nausea, in these patients it becomes the trigger.”
Recent studies, he added, have also suggested a possible genetic component, including differences in genes responsible for producing enzymes that break down THC in the liver.
The three stages of CHS
The first, or prodromal, phase is usually marked by morning nausea and abdominal pain, sometimes accompanied by fear of vomiting. Most patients continue eating normally, and some actually increase their marijuana use because they believe it will help relieve their nausea. This phase can last for months or even years.
Chronic cannabis use can cause nausea, repeated vomiting and severe abdominal pain
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During the hyperemesis phase, patients experience persistent nausea, repeated bouts of vomiting, abdominal pain, reduced food intake, weight loss and dehydration.
Many repeatedly take hot showers because heat appears to ease the nausea. One possible explanation involves heat’s effect on the hypothalamus, a region of the brain that regulates body temperature and is also involved in vomiting. The hyperemesis phase can continue until marijuana use is stopped completely.
The recovery phase then begins, with symptoms disappearing and normal eating resuming. Recovery can last days or months, but symptoms tend to return if cannabis use resumes.
How is CHS diagnosed and treated?
Many medical conditions can cause repeated vomiting, making diagnosis difficult. Doctors typically ask about symptoms and marijuana use and perform a physical examination. They may also order blood tests, measure electrolyte levels and liver and pancreatic enzymes, conduct pregnancy, urine and drug tests, or use X-rays, endoscopy, ultrasound or abdominal CT scans to rule out other causes.
If doctors suspect a neurological cause, a head CT may also be performed. CHS can be mistaken for cyclic vomiting syndrome, which produces similar symptoms.
Doctors are more likely to suspect CHS in patients who have used marijuana daily or weekly for an extended period, suffer from abdominal pain, severe nausea and frequent vomiting, and report relief after taking a hot shower.
There is no single test that confirms CHS. According to Cedars-Sinai, improvement after stopping marijuana use is what ultimately supports the diagnosis. Severe cases may require a short hospital stay.
Treatment can include intravenous fluids, anti-nausea medications, pain relievers, proton pump inhibitors to treat stomach inflammation and benzodiazepines for sedation or anxiety. In a small group of patients with CHS, applying capsaicin cream to the abdomen was found to reduce pain and nausea, producing an effect similar to that of a hot shower.
Completely stopping cannabis use is the only way to prevent symptoms from returning
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Symptoms usually begin to ease within one or two days after marijuana use stops. Full recovery requires complete cessation of cannabis use. Rehabilitation programs, cognitive behavioral therapy and family therapy may help patients stop using the drug. If cannabis use resumes, symptoms almost always return.
Possible complications
Severe and prolonged vomiting can lead to dehydration and dangerous electrolyte imbalances. Without treatment, complications can include muscle spasms or weakness, tears in the esophagus, seizures, kidney failure, abnormal heart rhythms and shock. In extremely rare cases, cerebral edema can also develop.
Prompt treatment of dehydration and electrolyte abnormalities can help prevent serious complications. Medical attention should be sought if severe vomiting continues for a day or longer. The only way to prevent CHS and keep it from returning is to avoid marijuana in all forms.
Stopping cannabis use may also improve lung function, memory, thinking and sleep and reduce the risk of depression and anxiety. Before seeing a doctor, patients are advised to write down their symptoms and questions. During the visit, they should keep track of recommended medications, treatments and tests and ask about the purpose and potential side effects of each treatment.