What is CHS? How nausea, stomach pain led to a diagnosis and link to cannabis

An increasing number of cases are being reported of a mysterious, rare condition possibly linked to cannabis use that has caused some people to become severely ill, according to an ABC News investigation.

While many people don’t think of cannabis as a substance that could make you violently ill, experts say some people develop this condition after consuming high concentrations of cannabinoids over long periods of time.

This rare illness is being reported more often around the same time as the rising legalization of marijuana and higher potency of cannabis products, from vaping to edibles.

Erica Hagler was an otherwise healthy 33-year-old who was struck down with a severe mystery illness when she says she was using cannabis multiple times a day.

"I felt like I was going to die," she told ABC News, adding that her symptoms included "the shakes, elevated heart rate, completely dehydrated and the vomiting was back to back to back."

After two weeks in the hospital with no diagnosis, Hagler said she was told by doctors she was suffering from a neurological or psychological disorder.

"They tested me for everything else underneath the sun," Hagler recalled. "I actually had the doctor walk into my room and say, 'we're sending you home because -- we can't find anything wrong with you.'"

Soon after, Hagler learned about CHS, cannabinoid hyperemesis syndrome, which affects people who use high doses of marijuana daily over an extended period of time.

"I diagnosed myself. Then I went back to my doctor and I said, 'this is what I think I have.' And then he said, 'oh, you know what? That sounds right. I've heard of this.'"

CHS is a rare condition that causes bouts of vomiting and abdominal pain. One Canadian study published in the Journal of the American Medical Association found that CHS-related emergency room visits increased 13-fold from 2014 to 2021.

"Given the prevalence of cannabis use worldwide, the very recent recognition of CH, and the paucity of CH literature, it is likely that this disease is underrecognized and underdiagnosed," the Mayo Clinic published in a case series.

"One challenge we have is that patients sometimes believe that their use of marijuana is helping them," Dr. Sam Torbati, co-chair of the Department of Emergency Medicine at Cedars-Sinai, told ABC News.

He continued, "We know that in patients with cancer marijuana actually reduces nausea and vomiting -- so for many patients, understanding that for them this is a poison -- is a tough pill to swallow."

Because of that misperception and a lack of tests for diagnosis, Dr. Torbati told ABC News that CHS is often overlooked or misdiagnosed.

"We give patients IVs to hydrate them. We do basic testing, just to make sure their kidneys aren't failing, that their electrolytes are not very disturbed," he said. "But really, to cure them of this condition, they need to stop smoking."

Hagler, who has been cannabis-free for five years, said she started a Facebook group to help others who say they are dealing with the condition.

"I get lots and lots of support," she said of the group "CHS recovery," that has amassed over 20,000 members.

"I don't want anyone to go through what I went through," Hagler said. "And if I can stop anyone to maybe consider moderating or just being careful or even knowing that this exists so that if they do get sick, that they can help themselves. That's really the ultimate goal."

Experts believe CHS is caused by overstimulated receptors in the body that bind with cannabinoids which can trigger a repetitive cycle of nausea and vomiting.

While some reports indicate temporary symptomatic relief with scalding hot showers or a heating pad, stopping marijuana use is the most successful way to manage the condition, experts say. If you believe that you may be suffering from CHS, talk to a doctor to seek medical attention.

Watch the full story live on Nightline at 12:35 a.m. ET or stream on Hulu.