The ongoing debate over cannabinoid hyperemesis syndrome

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Cannabinoid hyperemesis syndrome is a rare illness that makes heavy pot smokers vomit violently — but some people don't think it's real, or that it's caused by something other than cannabis, like the natural pesticide neem oil.
Wolfgang Claussen

Cannabis is celebrated for its ability to suppress nausea and alleviate pain, but for some long-term daily smokers it may do just the opposite. 

Cannabinoid hyperemesis syndrome (CHS) is a rare (and controversial, but more on that later) condition — only occurring in daily long-term users of marijuana — that leads to repeated and severe bouts of vomiting. It was first identified by a team of Australian researchers in 2004 when a cluster of patients in southern Australia came to emergency rooms complaining of cycles of vomiting and displaying “a spectrum” of involuntary symptoms, “from sweating, flushing, thirst and alteration in body temperature to colicky abdominal pain,” according to the paper. 

In a line you just can’t find in many research papers, the Australian team described nine out of 10 patients participating in “an abnormal washing behaviour during episodes of active illness.”  

“The symptoms of nausea, vomiting and abdominal pain would all settle within minutes in a hot bath or shower,” the researchers wrote. “Symptomatic relief was temperature dependent. The hotter the water, the better the effect.” 

More research on CHS emerged in medical journals as the years passed, but, unsurprisingly, it was met with suspicion, much of it from the cannabis industry. It’s understandable; many of the research samples were statistically too small. Boulder Weekly’s own Leland Rucker wrote skeptically about a 93-person, Michgan-based study of CHS back in 2013. Rucker spoke with Paul Armentano, then and still deputy director for the National Organization for the Reform of Marijuana Laws (NORML), who said “that such a phenomenon, when documented, is so rare to be — from a practical standpoint — irrelevant.”

But with decriminalization of marijuana spreading across the United States, this once novel illness is beginning to look more real to physicians. 

Dr. Cecilia J. Sorensen, an emergency room doctor at University of Colorado Hospital at the Anschutz medical campus, told the New York Times that “after marijuana was legalized in Colorado, we had a doubling in the number of cases of cyclic vomiting syndrome we saw,” which Sorensen says were likely related to pot use.  

The Times goes on to discuss a 2018 study of 2,127 patients at Bellevue Hospital in New York in which “155 patients who said they smoked marijuana at least 20 days a month, 51 heavy users said they had during the past six months experienced nausea and vomiting that were specifically relieved by hot showers.

“Extrapolating from those findings, the authors estimated that up to 2.7 million of the 8.3 million Americans known to smoke marijuana on a daily or near-daily basis may suffer from at least occasional bouts of CHS.”

Still, cannabis industry folks still seem reluctant to admit that cannabis might actually pose a medical problem for some fraction of the population. 

Just recently, on June 24, Russ Hudson, a cannabis consultant for over two decades based in Barcelona, told cannabis website Leafly he “would posit that most veterans in the cannabis industry — people with 20-plus years of experience — think that cannabinoid hyperemesis is a made-up or severely ‘misunderstood’ condition.” 

Hudson and others suggest that neem oil, a naturally occurring pesticide derived from seeds of the neem tree, might be the culprit. Neem oil contains the active ingredient azadirachtin, which can be toxic in large doses and cause severe vomiting and nausea. Azadirachtin poisonings, however, also include seizures, acidic blood and swelling of the nervous system, none of which are present in CHS. 

And while cannabis industry folks like Hudson can say anecdotally that they believe CHS is “made-up,” what isn’t made-up is the astronomical cost undiagnosed CHS places on patients. 

A 2019 paper published in the Journal of Addiction found that for 17 patients seeking treatment for cyclical vomiting, “the total cost for combined [emergency room] visits and radiologic evaluations was an average of $76,920.92 per patient. On average these patients had 17.9 [emergency room] visits before the diagnosis of CH[S] was made.”

A professor of emergency medicine told the New York Times, “I know patients who have lost their jobs, gone bankrupt from repeatedly seeking medical care, and have been misdiagnosed for years.”

Part of the problem — the heart of the problem — is that the research simply isn’t appropriately focused. 

Sorensen, of Anschutz medical center, led a 2016 review of the available body of literature about CHS, published between 2000 and 2015, and found that the bulk of the research concentrated on diagnostic and treatment concerns. 

In the paper the researchers noted that “the pathophysiology of CHS remains unclear with a dearth of research dedicated to investigating its underlying mechanism.” 

Yet another place where marijuana’s Schedule I classification likely prohibits critical research.

CHS patients who cease cannabis consumption report relief from their symptoms within weeks — easy as that. Perhaps it’s time for the marijuana industry to admit that cannabis might not be right for everyone.