Cannabis hyperemesis syndrome (CHS) is nothing new, but nonetheless lacks a diagnosis code. This means that nobody—including the Centers for Disease Control and Prevention, which is meant to track such things—knows the prevalence of the condition. It is, however, relatively rare. Medical sources say that it’s likely, as you’d expect, to become more common as nationwide cannabis use increases.
No one claims that CHS is lethal, but it is uncomfortable—and in an emergency room situation requires such medications as haloperidol, an antipsychotic, to relieve vomiting and pain. Business Insider recently reported the story of 29-year-old Alice Moon, who began using cannabis regularly to treat pain and nausea. She did so without problems for five years, but then began experiencing CHS symptoms monthly, and eventually weekly.
People who use any substance deserve access to relevant health information, without exaggeration in either direction. “Marijuana is somehow making millions violently sick” and “Mysterious Syndrome Related To Marijuana Use Begins To Worry Doctors” are two CHS-related news headlines from the past month alone. But CHS likely doesn’t affect millions, and it is less mysterious than some imply.
So this isn’t a Reefer Madness story, designed to scare people, nor a head-in-the-sand story, designed to appeal to those who see cannabis as a risk-free panacea.
Even pro-cannabis advocates agree that CHS exists. “It’s a diagnosis of exclusion,” Peter Grinspoon, MD, a primary care physician at an inner-city clinic in Boston, told Filter. Grinspoon is also on staff at Massachusetts General Hospital, teaches at Harvard Medical School, and authored the memoir Free Refills: A Doctor Confronts His Addiction (2016). “I’m not sure how you can really differentiate it from cyclic vomiting syndrome (CVS), idiopathic [unknown cause] vomiting, or just something else causing the vomiting—except for a cannabis history.”
CHS is caused by heavy long-term use of cannabis—i.e., it’s not a result of overdose or acute toxicity.
Experts believe that the action of the cannabinoid THC on our CB1 receptors, which are found all over the body but mainly in the brain, produces the symptoms of CHS—though the amounts of THC required, the duration of use in months or years, and why some people experience CHS and not others, are still unexplained.
One thing everyone seems to agree on: CHS is caused by heavy long-term use of cannabis—i.e., it’s not a result of overdose or acute toxicity. And it has one unusual manifestation: People afflicted like to take many hot baths or showers for relief.
A study published last month, based on emergency room visits in a Colorado hospital, also found that CHS is more likely to be associated with smoked than edible cannabis. Of 2,567 ER visits that were at least partly attributed to cannabis use, 18 percent of patients who inhaled it were said to have CHS, versus 8.4 percent of those who ate it.
“It’s very dramatic—patients are sometimes writhing on the floor, and they’re vomiting so much. It’s a horrible syndrome,” said Andrew C. Meltzer, MD, associate professor in the Department of Emergency Medicine and Clinical Research Director of GWU School of Medicine and Health Sciences. “It’s very different from any other kind of vomiting thing, and very disruptive to the ED.”
And in the worst cases, “repeated aggressive vomiting can cause tears in the esophagus.”
Unlike gastroenteritis, with CHS there is no diarrhea, no fever and more of a hypersensitivity to pain in the abdomen, Meltzer told Filter. There is an “overlap” with cyclical vomiting syndrome (CVS), in that many symptoms are the same. Blood work might be needed to rule out pancreatitis and hepatitis, and some patients get radiology.
Toxicology testing, on the other hand, is not very useful, because so many people use marijuana without showing these symptoms. Rather, it’s important to get a history of the extent and duration of marijuana use from the patient, said Meltzer. “Confusion exists in the medical literature,” he noted. In addition, he believes there is a pervasive failure to recognize chronic cannabis use as a possible cause of vomiting.
“We’re still trying to figure out how to make them feel better,” said Meltzer of CHS patients. “Typical anti-emetics like Phenergan and Zofran don’t work. Instead, we use antipsychotics, like haloperidol.” In fact, if the haloperidol works, Meltzer views that as diagnostic of CHS in some ways. The heat from capsaicin rubbed on the abdomen also provides some relief from pain.
In the patients Meltzer has seen with CHS, all “would qualify as addicted” to cannabis, he said. He doesn’t recommend using morphine for CHS pain because of what he sees as the addiction risk in this population.
Some CHS patients can’t be treated with emergency room management alone. Meltzer said he had to admit one patient for dehydration, fluids replacement, renal insufficiency, and other problems. “But now we’re getting more used to how to manage this with haloperidol and even Ativan. They are sedated, they sleep, and they go home.”
“I don’t care what people do in their free time, but in the medical history I try to include things that are pertinent.”
Ryan Marino, MD, an emergency medicine physician and medical toxicologist at the University of Pittsburgh, sees CHS about two-to-three times a month—but acknowledges it could be more, because sometimes it’s hard to be sure.
“The big issue is [CHS] is under-recognized,” said Marino, agreeing with Meltzer. “So a lot of patients get unnecessary testing.” For someone who comes in with a lot of nausea and vomiting, and is young and otherwise healthy, he says it’s important to ask about their marijuana use.
“I try to be as non-judgemental as possible” in asking those questions, he said. “I don’t care what people do in their free time, but in the medical history I try to include things that are pertinent.”
With emergency patients, the differential diagnosis is crucial and must be done quickly. “When there’s belly pain, you worry about things that need surgery, like appendicitis and the gallbladder,” said Marino. “CVS is kind of similar [to CHS], but people aren’t using cannabis.” So asking about marijuana use history can clearly help.
“The main thing seems to be people who use heavily and regularly: daily use or near-daily use,” said Marino. “With the rise of medical cannabis, more people have access to it, so maybe there are more presentations now than there used to be. But with no ICD [International Classification of Diseases] code, I don’t think you’d be able to say whether you can find prevalence.”
Marino acknowledges that there’s a fine line to tread in questioning patients, especially in situations where they are worried about law enforcement, and some healthcare providers are better than others at getting honest histories. “There are going to be people on the provide side who don’t get the truth out of patients, and there are patients who won’t disclose. This is why the way we treat patients is important.”
Whether they’re called in to consult in the emergency department or see a person in their office, gastroenterologists have a big role to play for CHS patients. CHS has been known about since 2004, but a seminal 2011 Current Drug Abuse Reviews article put gastroenterologists on the alert.
A year ago, Healio interviewed gastroenterologist Joseph Habboushe, MD for an article titled “Cannabinoid hyperemesis syndrome: What GIs should know.” Habboushe had surveyed 155 patients in an emergency department who reported smoking marijuana frequently and found that 32.9 percent of them met criteria for CHS. He concluded that the syndrome is vastly underreported.
“I would definitely ask” about marijuana use in the case of an otherwise-healthy, vomiting patient, said Lisa Gangarosa MD, AGAF, FACP, professor of Medicine at the UNC Division of Gastroenterology and Hepatology, speaking for the American Gastroenterological Association. “The diagnosis is largely made on the history.”
There is no clear test. “Basically, if the history fits, and if the patient stops smoking and gets better, that’s what it was.”
Some testing would be done to exclude other problems, such as stomach cancer, a large ulcer or gallstones, Gangarosa told Filter. It’s also important to conduct basic lab testing, such as for pregnancy, and then, if all of that testing comes back negative, to think about endoscopy and ultrasound of the gallbladder.
Gangarosa has only seen CHS in patients who have been “smoking pot,” not in anyone who has been prescribed dronabinol, which is synthetic THC.
There is no clear test for the syndrome. “In some cases you can say your impression is suspected marijuana-induced hyperemesis,” she said. “Basically, if the history fits, and if the patient stops smoking and gets better, that’s what it was.”
Surprisingly, many patients who use cannabis haven’t heard of CHS, said Gangarosa. For others, they don’t want to stop smoking, “and they don’t want to believe that this is the cause of their problems. It’s the same thing with pancreatitis—just because of the health harms, doesn’t mean people want to give up drinking.”
Andrew Meltzer, the ED physician, said that some of his patients have taken six-to-eight warm baths a day to relieve symptoms.
This reminds me of a personal experience. A member of my family had acute gastritis at the age of six, with a lot of vomiting, and was hospitalized for a week. All she wanted to do was lie in the hospital bathtub with the water as hot as possible. There was no marijuana involved, but bells went off in my head when I heard about the hot shower “cure.” Could this be a common way of responding to extreme vomiting and pain in general?
Experts stress that the hot shower treatment is anecdotal, and can’t be used as a sure sign of CHS. “But it’s something I ask people,” said Ryan Marino. “It seems as if most people have figured out” that it works. “It might be that they’re so symptomatic they try anything, and find the one thing that works.”
Like the capsaicin, which provides heat, and heating pads, heat from the hot shower on the belly might relieve the pain, said Marino. However, “I don’t think anyone has a good reason for the link” between CHS and hot showers.
The National Institute on Drug Abuse (NIDA) referred Filter to Kiran Vemuri, PhD, a research assistant professor at Northeastern University in Boston, who has a grant from the agency to find an antidote for synthetic cannabinoid intoxication.
That, of course, is a very different issue from CHS. But as an organic chemist, Vemuri has studied emesis from a CB1 antagonist perspective. He is aware of the paradox with THC: The synthetic version, dronabinol, is approved by the FDA to treat the nausea and vomiting associated with chemotherapy, as well as to increase appetite in wasting associated with AIDS, and for many other conditions.
How would the same substance that treats nausea induce it?
“This only happens in people who have been consuming cannabis for a long time,” Vemuri said. But he noted that most information in the literature is anecdotal and based on case histories. “People try to come up with a number”— how much cannabis, for how long—“but you can never really tell as to what causes the hyperemesis. Is it the dose, is it the strain?”
“If you know the CB1 receptor is implicated … the best treatment option would be an antagonist.” Except there isn’t one.
Vemuri has studied antagonists which induce nausea, with the CB1 receptor the biological target. CB1 receptors are all over the body, but most are in the brain, he said.
If you want to know everything the top researcher in emesis (vomiting) knows about the topic, look up the work of Linda Parker. It’s hard to study in animals, because not all of them even vomit.
There is no antidote for emesis itself, said Vemuri. “But if you know that the CB1 receptor is implicated, and the patient is presenting with an overdose of THC or synthetic cannabinoids, the best treatment option would be an antagonist.” Except there isn’t one.
As for the hot showers, CB1 receptors could indeed be involved, but there is no “concrete connection” to CHS or its treatment, said Vemuri.
And he cautions that “‘overdose’ is a big word when it comes to THC.” The dose, the strain, the route of administration all matter, he said. And because THC can reside in fat, and build up, it makes sense that some of the side effects could be worse in people who have consumed THC over a long period of time. “At the end of the day, anything in excess is not good.”
There was one medication which briefly showed promise for CHS—ribonabant—but it was removed from the market due to psychiatric side effects (suicidal ideation). “The target is so new,” Vemuri said. “But NIDA is definitely interested, and no one ever gave up on the target, and no one ever gave up on cannabis, and no one ever gave up on the antagonists. Recently I was at a conference where I got to know companies that are pursuing both CB1 and CB2.”
While hot showers may provide temporary relief, and anti-emetics and intravenous hydration can help “someone in the throes of repetitive vomiting,” for now, the best way for CHS patients to avoid further symptoms for good is to stop using cannabis, said Lisa Gangarosa, the gastroenterologist.
“That is always the recommendation,” agreed Marino. “It seems to be the only thing that makes it better or makes it go away. But it’s not always the easiest thing. It’s easy for me to say.”
The implications of quitting for people who use cannabis for medical reasons—and the difficulties for people who are addicted—are clear. But for now, the unknown minority of cannabis users unfortunate enough to experience cannabis hyperemesis syndrome have no other reliable recourse.