(HealthDay)—Long-term heavy marijuana use can cause chronic vomiting and abdominal pain in some people, new research suggests.
And the syndrome could become more frequent and pervasive as more states legalize use of the drug, according to health experts.
Cases of the disorder, which is called cannabinoid hyperemesis syndrome (CHS), doubled in Colorado as access to legal marijuana became widespread, said Dr. Kennon Heard. He is chief of medical toxicology for the University of Colorado Anschutz Medical Campus.
"All of the emergency departments in the state now are seeing this on a daily to weekly basis," Heard said. "There are a lot of patients ending up in the emergency room with this, and presumably there are even more who don't come to the emergency room, who just ride it out at home."
Patients who develop the syndrome typically smoke marijuana on a daily basis, and have been using it for six months or more, Heard said.
No one's sure what causes the syndrome, but it's suspected that heavy pot use triggers "some change in the brain pathways that react to marijuana," Heard said.
"You see a change in the nervous system, and the body's response to it becomes hypersensitized or starts reacting differently," he said.
Researchers first identified the syndrome in 2004, in a group of frequent marijuana users who experienced abdominal pain and vomiting with no apparent explanation, Heard said.
Cases of the syndrome doubled at two Colorado hospitals between 2009 and 2011, after the U.S. Attorney General ceased prosecution of marijuana cases in 2009, according to a study co-authored by Heard and published in the journal Academic Emergency Medicine in 2015.
Colorado legalized medical marijuana in 2000, and following the Attorney General's announcement, the number of medical marijuana licenses rose from just over 5,000 in January 2009 to nearly 119,000 in January 2011.
Denver Health and the University of Colorado Hospital experienced 87 diagnosed cases of the syndrome in the months following the liberalization of marijuana enforcement, compared with 41 cases prior to that, Heard and his colleagues reported.
Colorado legalized recreational pot use in 2014.
Marijuana users diagnosed with the syndrome have reported that hot showers help ease their symptoms. No one knows why this helps, Heard said, but it might be like rubbing a scrape to ease pain.
"Two inputs to the brain may start to cancel each other out," he said. "That's one of the best working theories."
Emergency room doctors working in states with legal marijuana need to take note of this phenomenon, and consider it when seeing a patient with extreme nausea and vomiting, said Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City.
"Patients typically present to the emergency department six to 10 times before a diagnosis of CHS [cannabinoid hyperemesis syndrome] is considered, often because many health care providers are simply unaware of this condition," Glatter said.
"After several visits to the emergency department with no clear reason to explain ongoing abdominal pain and vomiting, patients undergo a full medical workup," he said. These workups include "CT scans, MRIs and extensive blood tests to evaluate for gastrointestinal, endocrine or central nervous system causes for ongoing abdominal pain, nausea and vomiting," he added.
"Yet, a careful history to explore substance abuse—specifically, chronic and heavy marijuana use—may help to shed light on ongoing symptoms," Glatter suggested.
Dr. Scott Krakower, assistant unit chief of psychiatry at Zucker Hillside Hospital in Glen Oaks, N.Y., added that marijuana users should keep in mind that this can happen if they overdo it.
"We could potentially be seeing more of this as access is increasing," Krakower said. "They think cannabis is OK to use, but people don't realize some of the side effects that may accompany frequent use."
People experiencing the syndrome obtain relief if they stop using pot, but it can take a while before symptoms subside, Heard said.
"Over a few days to a week after people stop, they start feeling better," he said. "We don't know if people can go back to using again. We just don't have that information at this time."
Recreational use of marijuana is legal in eight states: Alaska, California, Oregon, Washington, Nevada, Colorado, Massachusetts and Maine. Medical marijuana is permitted in 26 states and the District of Columbia.
Explore further: Case report: cannabinoid hyperemesis syndrome
For more on cannabinoid hyperemesis syndrome, visit Saint Luke's Health System.