Cyclic Vomiting Syndrome: The truth about the scary-sounding illness sending weed users to the ER

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There's a frightening new trend in cannabis, and the headlines make it sound dire.

"Mysterious Marijuana-Related Illness Popping Up in Emergency Rooms," the Huffington Post reported. "Cyclic Vomiting Syndrome: It's as Terrible as It Sounds," a Fox News story proclaimed. "Mysterious Syndrome Torments Some Heavy Pot Smokers With Constant Nausea" was the Global News take, while the Sacramento Bee went the more colloquial route with "Stoner Barf: Yes, It’s a Thing, and It’s Way More Common Than You Think."

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It's enough to make you think twice before that next bong rip. But how worried should you actually be? Let's break down this new medical oddity.

What is this condition?

The illness is cannabinoid hyperemesis syndrome, or CHS. Australian researchers first identified the condition in 2004, when they studied patients who suffered from peculiar nausea following years of chronic cannabis abuse.

The patients all endured cyclical bouts of abdominal pain and severe, uncontrollable vomiting that the doctors connected to cannabis toxicity — a “paradoxical” finding, given marijuana's reputation as an effective anti-nausea treatment.

Several refused to consider cannabis the cause of their illness and continued to use it with the hope of alleviating their symptoms.

Almost all exhibited “abnormal washing behavior,” taking multiple hot showers or baths a day — even waking overnight to do so. This appeared to be a learned coping strategy for relieving nausea: The hotter the water, the better the patients felt.

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The study's authors guessed that their patients exhibited CHS only after years of cannabis abuse (recovering completely when they stopped using marijuana and succumbing to their symptoms once more as soon as they started consuming again) because the compounds in marijuana can accumulate in the body's fat tissue.

After a while, they theorized, the amount of cannabinoids would reach toxic levels in “sensitive” patients, causing a variety of painful symptoms. Besides quitting pot, there doesn’t seem to be any obvious cure.

Why is cannabinoid hyperemesis syndrome in the news lately?

Some ER physicians say they are seeing more and more cases. But for all the claims that the illness is on the rise in states with legalized marijuana, there’s just one data point on the subject: According to a 2015 study, the prevalence of CHS doubled in Colorado as the state embraced medical marijuana.

That sounds worrying, but here’s some context: The study included just two Colorado hospitals, noting 41 reports of “cyclical vomiting” per 113,262 emergency room visits between 2008 to 2009. In the next couple of years, it was 87 cases per 125,095 ER trips. So we can see that the condition is relatively rare.

Moreover, “cyclical vomiting” is not necessarily CHS. Another possible is cyclical vomiting syndrome, or CVS. These episodes of intense nausea aren't well understood either, but they seem to be brought on by a variety of triggers apart from cannabis, including emotional stress, anxiety and even hot weather.

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With more U.S. adults using marijuana in an era of reform, it's reasonable to expect an uptick in patients who develop CHS. Yet the apparent surge in cases may involve another factor: that doctors are just beginning to recognize the symptoms. In years past, people with CHS typically sought medical attention multiple times, often receiving misdiagnoses. These days, CHS symptoms — the hot showers in particular — can more quickly lead to a correct assessment.

Doctors have also speculated that legalization doesn't create more marijuana-related health emergencies, but makes the prospect of calling for help more comfortable. Meanwhile, three years into a recreational marijuana economy, Colorado officials say that with consumption levels remaining steady, they've actually seen a drop in cannabis-related poison control calls and ER visits.

All of which suggests we don't have to freak out about an epidemic just yet.

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Who is at risk for CHS — and what else are we learning about it?

As with much of cannabis research, the science on CHS is murky and scant.

Regular marijuana users tend to express skepticism of the condition — but denial is dangerous, with some CHS patients administering more marijuana in an effort to alleviate their nausea. In the 2004 Australian study, “virtually all” the patients “had increased their marijuana consumption at the time of illness.”

Yet that paper, which established the idea of CHS in medical literature just 13 years ago, has come under scrutiny from other experts in the field: “Cannabis has been consumed for many centuries and is currently used by millions of people in many countries,” three hospital physicians wrote in a 2006 reply to the original study. “It is hard to believe that a distinctive syndrome caused by cannabis has never been noted before by users or clinicians.”

There's little to go on when it comes to pinpointing a mechanism for CHS, or which people are most susceptible. A 2011 study pointed out that two cannabinoids — cannabidiol (CBD) and cannabigerol — may override marijuana's anti-nausea effects in large doses, prompting nausea instead. Then there's the fact that cannabis disrupts normal digestive processes, except that outcome is usually suppressed by the effects of tetrahydrocannabinol (THC) on the central nervous system. Perhaps, for some, that dynamic reverses.

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The hot bathing compulsion may also provide a clue, another paper noted, as it hints that cannabis toxicity is causing a disequilibrium in the body’s temperature regulation systems. When these reactions are more fully explored, they may give us a better sense of warning signs; at the moment, all we can say about the onset of the illness is that the initial phase can last for years, with patients developing early morning nausea, a fear of vomiting and abdominal discomfort, before the episodes of severe vomiting kick in.

Then there are those who believe we ought to be taking a closer look at our cannabis as well as the patients stricken with CHS: A doctor from the Seattle clinic Greenleaf Health Care, for example, told Leafly that he suspected potent pot grown with additional chemicals may be the ultimate culprit. But like all the other proposed causes of CHS, we just don't have the evidence to prove it.

I use marijuana every day — am I going to get CHS?

Going by the numbers we have: probably not.

One study found that CHS may not present until around 20 years of consistent cannabis abuse. And although the authors of the 2011 paper admitted that the syndrome is likely underreported, they couldn't help but notice just how few people develop CHS, especially given “large prevalence of marijuana use in the world.”

So despite the absence of statistics that would accurately convey the percentage of cannabis users struggling with CHS, it seems safe to say that it's quite uncommon — or uncommon enough that the parade of frightening headlines about it may exaggerate the problem somewhat.

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Still, cannabis is known to affect everyone differently, and to use it at all means running the risk of various (and widely debated) negative effects. And remember: Whatever health problem you're facing, “more weed” isn't an automatic fix.

In fact, as bold as it may sound, it's definitely always better to see a doctor.