The top reason marijuana users seek help in ERs is a malady known as cannabinoid hyperemesis syndrome, or CHS.

CHS happens exclusively among those who have used marijuana for years, and, typically, on a daily basis. It involves severe stomach pain and bouts of vomiting that can last days, only to abate and reemerge weeks or months later. While there are treatments to ease the pain and discomfort, there’s only one cure, and that’s cutting off cannabis use. For the latest on CHS, UCHealth Today caught up with Dr. Kennon Heard, professor of Emergency Medicine at the University of Colorado School of Medicine and chief of that department’s medical toxicology section. He see patients in the emergency departments at UCHealth University of Colorado Hospital on the Anschutz Medical Campus and at UCHealth Highlands Ranch Hospital.

How common is CHS, and is the number of patients with it climbing?

It’s hard to say, Heard says. That’s in part because there’s no diagnostic code for cannabinoid hyperemesis syndrome. When patients are discharged from a UCHealth emergency department, the official diagnosis is typically “vomiting,” though the CHS details are entered into the medical record’s notes.

Anecdotally, Heard says, the number of CHS patients whose symptoms are serious enough that they end up at a hospital for treatment has leveled off at one or two per day at University of Colorado Hospital.

But the risk may be rising from a national perspective. Twenty-four states and the District of Columbia allow recreational marijuana use, and recreational legalization is on the ballot in Florida, South Dakota, and North Dakota in November. In addition, a 2022 U.S. national drug use survey found that more than 4.5 million 18- to 25-year-olds use the drug daily or near daily, with 81% meeting the criteria for cannabis-use disorder. That’s the type of heavy use that invites CHS.

What causes CHS?

The cause of CHS is both obvious (heavy, prolonged marijuana use) and mysterious, because doctors and researchers don’t know the exact triggers. What’s clear is that THC, the psychoactive ingredient in cannabis, and other cannabinoids stay in the body for a long time because, as Heard put it, “they live in your fat.”

“So, people might not be actively smoking it but still might have a fairly significant amount of THC coming out of your system, and it can be enough to trigger symptoms,” he said.

What can you do at home to relieve CHS symptoms?

Hot showers or baths often help, and the relief from symptoms through methods like these are a telltale sign that the problem is indeed CHS. But Heard cautions that, while many people report feeling better after hot showers or baths, “that doesn’t seem quite as universal as we initially thought it was.”

And, of course, stop using marijuana, which is the only long-term solution.

What medical treatments work to alleviate CHS symptoms in health care settings?

Intravenous fluids and an antiemetic (medicine to stop vomiting) are two standard approaches, Heard says. The common antiemetic odansetron doesn’t seem to work, he says. Fortunately, an older medication, droperidol, does seem effective in stopping the vomiting.

But occasionally, patients who arrive at a hospital with what initially looks like CHS can instead have pancreatitis, gastritis, gastrointestinal reflux disease (GERD), appendicitis, or other problems. So, Heard says, these patients often end up going through a lot of testing.

“Our first job is figuring out what’s wrong, and that makes it a little bit complicated,” he says, because CHS “looks like a lot of other stuff.”

While marijuana legalization has been a driver of CHS cases, the growing social acceptance of cannabis use has helped doctors identify the syndrome more quickly, because patients are more open about their use, Heard says.

As miserable as CHS can be, Heard said patients don’t need surgery, and it’s not a mortal risk. The best solution is straightforward: Stop using marijuana, and you’re going to get better, he says.

Is there a particular demographic that seems prone to CHS?

In the early years of legalized recreational marijuana in Colorado, young men were most likely to show up in emergency departments with CHS, Heard says. But as marijuana use has become more widespread, patients into their 40s and 50s are arriving with CHS, and with no particular pattern with regard to gender or race. Geriatric patients remain rare, he says.

Are there marijuana strains that have been identified as protecting people from CHS?

No.

What other marijuana-related problems are emergency departments seeing these days?

While cannabis-induced psychosis (also called cannabis-associated psychotic symptoms, or CAPS) has gotten recent attention, it appears to be rare, and those with mental health issues such as bipolar disorder, anxiety, psychosis, depression, addiction, and personality disorders are most at risk.

Cannabis also has been found to have cardiovascular effects. Edibles, given the delay in the drug’s psychoactive impact because of the need for digestion, can lead to emergency department visits, as can accidental pediatric exposure of edibles in particular (cannabis is bad for kids in general). Heard says pediatric cases are down, however, thanks to steps the Colorado marijuana industry has taken, some by force of legislation, in packaging and individual dosing.

Since Colorado legalized ‘medical marijuana,’ I assume there are medical benefits. Is that true?

Some people with conditions like epilepsy, multiple sclerosis, chronic pain and nausea believe that marijuana helps them. But the efficacy of marijuana use is not clear. Heard and other physicians say the lack of solid, peer-reviewed research on cannabis’s effectiveness remains reason for skepticism. Its federal status as a Schedule I drug continues to hamper medical-research efforts.

“We subject pharmaceuticals to a standard evaluation for efficacy and safety to see if they help with whatever the condition is,” Heard said. “That really hasn’t happened with cannabis. So, I think it’s difficult for me as a physician to say, ‘Oh, cannabis is a medication.’”

As recreational drugs go, there are worse, he adds.

“If you want to talk about a recreational drug, I’ll tell you right now, I spend a lot more of my time taking care of patients who have problems with alcohol and methamphetamines than with cannabis,” he said.