Cannabinoid hyperemesis syndrome: a rare health complication putting chronic cannabis users at risk

As cannabis legalization continues to spread across the country, doctors are sounding the alarm about the potential health risks of the quickly changing drug. One rare condition is sending chronic marijuana users to emergency rooms. Researchers are attempting to spread awareness about that condition, cannabinoid hyperemesis syndrome (CHS), and the need for more government oversight in the legal cannabis industry.

What is cannabinoid hyperemesis syndrome?

A rare but severe condition, cannabinoid hyperemesis syndrome is caused by heavy cannabis use and is "marked by nausea, vomiting and pain," said The New York Times. It can lead in some cases to extreme dehydration, seizures, kidney failure and cardiac arrest. In rare cases, it can lead to death. The syndrome was first documented in 2004.

The onset of CHS tends to affect people "after years of using marijuana many times a week," per the American College of Gastroenterology. The initial symptoms include nausea, belly pain and persistent vomiting. After about 10 to 12 years of chronic marijuana use, "patients begin to have a strong feeling of sickness, throwing up and belly pain." Some medical professionals refer to symptoms of CHS as "scromiting," a term that combines "vomiting" and "screaming," said the Cleveland Clinic. Some patients scream while they vomit due to the intense belly pain.

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A telltale sign of CHS is that heat often temporarily relieves the condition's symptoms. Hundreds of people told the Times that they spent hours in hot baths and showers. Some were even "burned by scalding water," and one was injured when "in desperation, he pressed his body against a hot car," the outlet said. With there being so little research on the syndrome, experts are not sure why heat soothes the symptoms, "nor why certain chronic marijuana users develop it and others don't," said the Times. The onset of CHS appears to be related to the way marijuana interacts with the body's endocannabinoid system, which helps regulate bodily functions like sleep, digestion and pain perception. People with severe CHS symptoms frequently need emergency care.

While the biggest risk factor for CHS is heavy cannabis use, "most people who smoke cannabis daily don't get this," Christopher Andrews, a clinical professor of gastroenterology at the University of Calgary, said to National Geographic. Among those who do, it is not a constant affliction. "It comes and goes and it happens in cycles," Deepak Cyril D'Souza, the director of the Yale Center for the Science of Cannabis and Cannabinoids, said to the outlet. If it continued indefinitely, that would "force a person to stop" using cannabis.

Why might CHS be on the rise?

Without more research, there is no definitive answer, but doctors have linked the increase in CHS cases to widespread legalization, along with higher tetrahydrocannabinol (THC) content in modern marijuana. The commercial industry that blossomed after legalization "touted its products as beneficial" while focusing on "engineering a quicker, more intense high," the Times said. Researchers in a 2024 study published in the Journal of Clinical Gastroenterology compared hospitalizations for CHS at a large hospital in Massachusetts in 2012 and 2021, before and after cannabis was legalized in the state, and found a significant increase in hospitalizations.

In the 1990's, cannabis typically contained about 5% THC. Modern companies have "turned out inconspicuous vape pens, fast-acting edibles and pre-rolled joints infused with potency enhancers and concentrates" that contain as much as 99% THC. With these new products, hospitals saw influxes of CHS, and researchers called for more public health guidance and education for providers. "Awareness was slow to spread."

Experts say the medical field is woefully behind on understanding the rapidly changing drugs. "There's a difference in legalizing the original cannabis on the planet and the products that exist today," neuroscientist Yasmin Hurd said to the Times. Hurd was the lead author of a 2017 report on the health effects of cannabis from the National Academies of Sciences, Engineering and Medicine, which warned that the lack of evidence-based information posed a public health risk. Until more studies are done on cannabis in all its new forms, putting cannabis "under the umbrella of a safe, legal drug is wrong," she said. "It's misleading at best and dangerous at worst."