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Some stoners become suddenly and violently ill from cannabis — and scientists aren't sure why

By Troy Farah,


Erica, a 38-year-old from Boston, used to consume so much marijuana that she considered herself an "Olympic smoker." She would carry a bong from room to room while working from home, and would even wake in the middle of the night to toke up. She consumed as much weed as she could, until one day she just couldn't anymore. Cannabis began making her extremely sick — but at first, she had no clue.

"I went to MGH [Massachusetts General Hospital], which is one of the top hospitals in the country, and I ended up nearly dying," Erica, who asked not to disclose her last name due to stigma around drug use, told Salon. "I could not stop vomiting or shaking. I was getting to the point where I couldn't walk because I was so weak. I lost 30 pounds in three weeks."

After several weeks in the hospital, being tested for everything that could possibly trigger her illness, the medical staff came up short and discharged her. There was nothing more they could do.

"I got mad at the doctor and I said, 'You just want my bed. You're trying to kick me out of here because you just need my room.' And they said, 'No, we literally can't find anything wrong with you,'" Erica said. Eventually, it dawned on her that her excessive cannabis use might be the trigger. "In the back of my head, I'm saying, 'no, no, no, cannabis can't hurt me like that, there's no way.' Well, I got home, I started doing research and I ran across the little information that was on the internet about CHS."

CHS stands for cannabinoid hyperemesis syndrome, a form of excessive vomiting that is triggered by drugs like THC and CBD, two of the active chemicals in cannabis. While CBD is a cannabinoid more often considered medicinal, THC is better known for its ability to get people high. However, both drugs have medical benefits that humans have known about for centuries. The "medical" part of medical marijuana is not a euphemism. Compared to some drugs, it is pretty safe, and most people tolerate it pretty well.

But safety is relative. Erica and thousands of people like her have found out the hard way that their bodies can no longer tolerate this drug. Even more curious, CHS can be triggered spontaneously in people who have smoked or otherwise used cannabis for years. For unknown reasons doctors and scientists are still trying to understand, in very rare cases cannabis can trigger intense, overwhelming vomiting episodes (hyperemesis) that can last for days or even weeks. "Scromiting," in which a patient screams uncontrollably while vomiting, is not unheard of.

Erica struggled to find reliable information about her condition, so a few years ago, she started a Facebook group dedicated to CHS. Currently standing at over 20,000 members, the group allows people to compare their symptoms, support one another and attempt to find answers about this mystifying condition. But so far, aside from abstaining from weed, there isn't much people can do to feel better.

"It's kind of a mysterious illness in the sense that we really still don't understand fully what causes it," Kyle Boyar, a cannabis scientist based in San Diego who has been studying the plant's chemistry for over a decade, told Salon. Boyar was previously the vice-chair of cannabis chemistry for the American Chemical Society and specializes in cannabis testing and analytical chemistry. "A lot of physicians have never been trained on this. It's an emerging condition and there's a lot of misdiagnosis that happens with CHS as well."

Part of the reason this is all so strange is because THC is an antiemetic — a very effective drug at treating nausea. Even the federal government recognizes this and has for nearly four decades. Dronabinol is synthetic THC that is prescribed to chemotherapy patients experiencing severe nausea and vomiting. The Food and Drug Administration approved dronabinol in 1985 and it is still used today.

So the idea that THC can cause the opposite effect is somewhat counter-intuitive, described by some medical experts as "paradoxical," which is perhaps why some CHS patients initially use even more cannabis to relieve their symptoms. This, of course, tends to only make the situation worse.

"I have talked to a number of people who have experienced CHS and it clearly is quite traumatic for them," Dr. Bonni Goldstein, author of the book "Cannabis is Medicine," told Salon in an email. Goldstein is also the medical director at Canna-Centers, a California-based medical practice devoted to medical marijuana treatment. "CHS makes people feel terrible physically, often requires multiple visits to the ER where expensive work-ups are done before the correct diagnosis is made and then these individuals are told to avoid cannabis for the rest of their lives — something that they do not want to do, as they previously found some benefits from using it."

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For Alice Moon, a cannabis entrepreneur living in Los Angeles, giving up cannabis was especially hard, given that she has worked in the cannabis industry for over a decade as an influencer and publicist. Her enthusiasm for marijuana landed her features in High Times, LA Weekly, CNN and she appeared on Viceland's Bong Appetit. But in 2016, she began developing infrequent vomiting episodes every few months.

"Then, as time progressed, it started becoming more frequent," Moon told Salon, describing a puking jag that lasted two weeks nonstop. "I saw numerous doctors who couldn't figure out what was wrong with me. I was poked and prodded, had every test done you can imagine. And it took about two years before a doctor finally diagnosed me with CHS."

Moon still works in cannabis PR, but says she often can't attend clients events because even the secondhand smoke will affect her. Searching for answers, she eventually found Erica's Facebook group and the two became long-distance friends. Together, they have tried to fill in the gaps about this condition due to a severe lack of quality research on CHS, often by surveying group members.

"I don't believe that CHS is rare. I just think it's not documented," Moon said. "There's no actual tracking going on. We don't know how many people truly have this condition in America."

The condition, which can be broken down into three stages, usually tends to develop in someone who has been using large amounts of cannabis daily for several years. The first stage is called "prodromal," characterized by anxiety, sweating, skin flushing and nausea, usually in the morning.

"This stage can last for months without any vomiting. Often the individuals struggling with this will continue to use cannabis to try to treat these uncomfortable and concerning symptoms," Goldstein said. "The second stage is called 'hyperemetic' and is characterized by abdominal pain, nausea and vomiting, and will very often include a compulsion to bathe or shower in hot water, which often provides relief. The third stage is the recovery stage, with resolution of symptoms with abstinence of cannabis use. This stage can be prolonged for weeks or months for some. Unfortunately, CHS has resulted in a few deaths due to electrolyte disturbances."

Figuring out someone has CHS generally involves a lot of trial and error. The term was first coined in 2004, but it's only been documented in a few hundred patients to date. Few drugs seem to treat it. An anti-nausea medication call Zofran (ondansetron) doesn't seem to help, but some patients respond with Haldol (haloperidol), an antipsychotic drug used to treat schizophrenia, or benzodiazepines like Xanax.

Treating patients for dehydration is critical, because the excessive vomiting can cause kidney failure and death, which has happened in a very small number of cases. (It's worth noting that alcohol and even overdosing on caffeine can also kill this way.) If you or someone you know is suffering from chronic vomiting like this, a visit to the emergency room is prudent, whether cannabis is the cause or not.

Some people report that home remedies like hot baths or showers can relieve CHS symptoms while others swear by rubbing capsaicin cream on their abdomen, which contains the chemical in chili peppers responsible for that signature burning sensation. But these tricks may not work for everyone.

"65 percent of members say that they find relief with heat. There's a smaller percentage that says they actually find relief with the opposite, so very cold showers," Erica said. "What I have found is it's actually about shocking the [central nervous] system, so even alternating between hot showers and cold showers causes a temporary relief. But it's very, very temporary and it does not help everyone. Personally, I was not one of the people that it did help."

CHS is idiopathic, meaning we don't know why the body suddenly starts reacting this way. The lack of information has led to blaming everything from pesticides to neem oil to plant viruses that attack cannabis, like latent hop viroid. But pesticide or neem oil poisoning present very differently than CHS symptoms and it's not possible for plant viruses to infect humans.

Dr. Ethan Russo, a neurologist and psychopharmacology researcher who has been studying cannabis for nearly three decades, has been looking into the genetics of CHS patients to see if they metabolize cannabis differently. In a study published last June in the journal Cannabis and Cannabinoid Research, Russo and his colleagues tested 28 patients and 12 controls. It's a small sample size, but for various reasons, Russo had trouble recruiting patients. Nonetheless, they were able to identify five genes with statistical significance in CHS patients that could unlock the mystery of this illness.

"In each case, the five mutations that we noted seem to relate to the pathophysiology of the disorder. They're not just random genes that don't have any obvious relationship to the disorder, but rather they help explain the phenomenology of the disorder," Russo told Salon in a call. For example, one of these genetic mutations involves the TRPV1 receptor, which is found in nerve cells and helps respond to heat.

That's not all the the gene does, though. "This gene is in the gut, it's in the brain. It's been linked to anxiety and pain responses and also affects motility: how the gut moves," Russo said. "And the mutation that we saw is not one that was previously listed in the National Library of Medicine database. But the fact that there was a mutation here in the vast majority of the CHS patients — 71 and a half percent — really indicates links of this mutation to gut disturbances, as well as the hot water bathing on behavior and also points out why capsaicin ointment on the skin may help. That all relates to TRPV1 function."

Despite this preliminary evidence, we need far more research into how these mechanisms work and how to treat them. Unfortunately, some prohibitionists have used CHS as a wedge to argue that this is why cannabis should have remained illegal in the first place. It's not a position Moon or Erica take, noting that CHS probably existed long before medical marijuana was legalized.

"There's members in the group that have said, 'My aunt died from a mysterious vomiting syndrome in the '70s and she used to smoke a ton of weed," Erica said. "He thought that she had it. The thing is, even 20 years ago, no one was talking about being sick like this from smoking weed. You can't tell your doctor because it was illegal. No one was talking about it. So this could be much older than we think it is. But we just don't know."

Russo said that despite its benefits, medical marijuana has to be put into context.

"Yes, there can be serious side effects of cannabis usage and CHS is one of the best examples," Russo said. "There are just some people, such as those with CHS, that should not be using it any longer. But again, this is a tiny percentage and it's not any reason to increase prohibition or anything else. It is a reason to try to understand the problem and properly advise people."

Erica agreed, noting that prohibition was actually standing in the way of finding treatments for CHS patients, due to how expensive and difficult it is to study marijuana under its current federal legal status.

"I really hope that people understand that the CHS community is not against weed — 99 percent of us are envious that we don't get to smoke anymore," Erica said. "I can't tell you how many times I've been attacked by people thinking I work for Big Pharma or that I'm anti-weed and it's just not the case. I'm just pro-awareness. People need to know."

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