This strange syndrome is linked to regular cannabis use—and cases have doubled
Nausea. Severe abdominal pain. Compulsive bathing. These are some of the hallmarks of cannabinoid hyperemesis syndrome, a medical condition that’s on the rise.
Sierra Callaham was 23 when she had her first monthlong bout of daily abdominal pain, nausea, and cyclical vomiting. She was bewildered but chalked it up to stress—work had been rough, and she was on the outs with her family. Antinausea and antianxiety meds got her through most days, and in the evenings, when she wasn’t actively vomiting, she kept up her usual routine of smoking a little pot. She wanted so badly, she says, “to relax and not be as present in my body.”
Callaham lives in Washington State, where recreational cannabis has been legal since 2012, and she had long been a daily if moderate user: a bit each night, as a sleep aid. Before her first gastrointestinal ordeal, in late 2020, she was vaping concentrated cannabis oil from a battery-powered pen. After her symptoms seemed to pass, she switched to smoking pre-rolled joints for a few years before returning to vapes.
Then, in early 2024 came another weeks-long attack—debilitating stomach cramps and daily, uncontrollable vomiting—that sent her twice to the emergency room. On a visit to urgent care, a doctor asked if she used cannabis. Every night, Callaham said. She was shocked when the doctor gave her a provisional diagnosis: cannabinoid hyperemesis syndrome (CHS), sometimes simply called weed sickness.
Recurring episodes of nausea, vomiting, and abdominal pain are the classic symptoms of this puzzling gastrointestinal condition, which is associated with long-term frequent use of marijuana, particularly high-potency products. Doctors in Australia first described cannabinoid hyperemesis syndrome in 2004 (cannabinoids are compounds, like THC or CBD, found in marijuana; “emesis” is the clinical term for vomiting). Just how many suffer from CHS is unknown, but one 2018 study, extrapolating from a survey administered to ER patients, put the number as high as 2.75 million people in the United States each year. A recent research summary from the Journal of the American Medical Association suggests it is increasingly diagnosed: ER visits for CHS doubled in the U.S. and Canada between 2017 and 2021.
What’s behind the rise? One factor, says Deepak Cyril D’Souza, a professor of psychiatry and director of the Yale Center for the Science of Cannabis and Cannabinoids, is the increasing potency of cannabis products. Thirty years ago, samples seized by the U.S. Drug Enforcement Administration averaged 4 percent THC content by weight. As of 2022, that average is about 16 percent; the oil in vape cartridges like what Callaham was using can reach as high as 85 percent.
Research also points to the broadening legalization of recreational weed. In one characteristic study, published in 2022 in the American Journal of Gastroenterology, researchers compared admissions for CHS at a large Massachusetts hospital between 2012 and 2020, noting a significant uptick after cannabis was legalized in the state in late 2016.
All the same, CHS is a frustratingly spotty affliction. “Why some people seem to be vulnerable to this and not others really seems to be a mystery,” D’Souza says.
Read more of our reporting in The New Cannabis
Who’s at risk for CHS?
“Most people who smoke cannabis daily don’t get this,” acknowledges Christopher N. Andrews, a gastroenterologist and clinical professor at the University of Calgary in Canada. Among those who do, the symptoms aren’t constant. “It comes and goes, and it happens in cycles,” says D’Souza. Andrews believes that if CHS symptoms were more consistent, it might motivate more patients to stop using cannabis.
One theory about the cause of CHS involves the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the body’s stress responses by adjusting hormone balances. Chronic cannabis use “makes that pendulum swing further one way than the other,” Andrews says, perhaps triggering symptoms by abnormally stimulating the HPA axis.
There may also be a genetic susceptibility at work, and depression and anxiety are common in people with the syndrome. “The paradox is, we don’t understand what’s triggering this in a particular moment,” says David Levinthal, director of the Neurogastroenterology and Motility Center at the University of Pittsburgh Medical Center. Among the leading suspects, he says, are lack of sleep and intense stress.
Another strange aspect of CHS: Sufferers tend to spend a lot of time in the shower. “People with CHS often report temporary relief of symptoms from bathing in hot water, which may lead to compulsive bathing,” says Maria Isabel Angulo, an assistant professor of internal medicine and pediatrics at the University of Illinois in Chicago. This suggests that the area of the brain that helps regulate body temperature—the hypothalamus—might be involved in the syndrome.
Desperate for relief
Whatever the causes, the longer-term consequences of CHS can far exceed the lengthy stretches of intense discomfort. Complications can include severe dehydration and electrolyte imbalances, which can lead to kidney injury, heart-rhythm abnormalities, and seizures. In rare cases, such complications have even proved fatal.
As hard as its symptoms are to ignore, accurately diagnosing CHS can be tricky, physicians say, partly because those symptoms mimic other gastrointestinal conditions and because patients aren’t always straightforward about their habits. “The way to make the diagnosis,” Andrews explains, “is to [have the patient] come off cannabis, proving retroactively that it’s the cannabis” causing the symptoms.
Giving up pot is also the only known lasting CHS solution. And while the myth of nonaddictive cannabis persists, quitting cold turkey from regular use can cause symptoms like anxiety, irritability, sleep disturbances, and loss of appetite. Relief, moreover, can take weeks or months. “Since it can take such a long time to get better once cannabis is stopped,” Andrews says, “people often may think that the cannabis has nothing to do with their symptoms.” Even the prospect of abstinence may make some chronic users reluctant to come to terms with the condition.
Not Callaham. When her urgent care doctor first handed her literature about CHS, she was skeptical. “I was like, there’s no way—I’m so intentional about how I consume,” she says. “But as soon as I read the materials, I thought, Oh no. And that was the day that I quit.”
She’s been weed-sober ever since. It hasn’t been easy—she’s fought cravings and had to retrain herself to recognize what relaxation feels like when she isn’t high. But it’s easier when Callaham remembers what the depths of hyperemesis felt like. “I was so desperate,” she says. “I was so desperate to feel better.”
This story originally published November 11, 2024. It has been updated.
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