As cannabis use expands across the United States, there have been increasing reports of a phenomenon called cannabis hyperemesis syndrome (CHS).
While CHS is actually a relatively rare condition, occurring in about 3% of chronic cannabis users, its symptoms can be severe, causing intractable nausea, vomiting, and abdominal pain, sometimes leading to more severe consequences (1)..
I have been a registered medical cannabis practitioner for over 10 years and have treated nearly 1500 patients. And yet, in all that time, I have only had two confirmed patients with it.
However, many years ago, while still working full-time as an emergency medicine physician, long before CHS had been recognized as a clinical entity (it was first described in the literature in 2004), my colleagues and I had frequent encounters with a patient who clearly was suffering from it. We were working in a busy suburban New Jersey hospital when this patient would come in. He was a young man in his mid-20s, casually dressed and very pleasant. He was troubling and unusual, though, in that each time he suddenly appeared in the ER, he would plant himself in the middle of its chaotic main treatment area, in front of the nursing station, and begin to retch. As his occasional bits of vomitus splashed on the floor in front of us, it was hard to be sure if he was vomiting uncontrollably or being theatrical. The retching would happen not just once or twice but multiple times, and his actions were sometimes enhanced by sticking his finger down his throat.
His visits left us all befuddled, the subject of frequent clinical conversation, but with no real idea of what was causing his symptoms.
It was only years later that any of us recognized that he had CHS. The fact that the only real history he ever shared was about his heavy use of cannabis should have tipped us off, I suppose. But I honestly don’t think many in the world of ER medicine were tuned into this phenomenon in those days, and what was understood then was that cannabis was good for preventing nausea and vomiting, not the exact opposite.
As a physician in practice for 40-plus years, I am troubled to recognize that despite its many potential benefits, especially in cases where nothing else has worked, there doesn’t seem to be a way to return to using medical cannabis when CHS develops.
Some time after I began as a medical cannabis practitioner, I was alerted by a patient that she'd suddenly developed this condition. She was an elderly woman who, after several years of successfully using cannabis, wound up in the ICU with kidney failure. And while she did regain kidney function again, it was truly unfortunate because up till that point, cannabis had been the only thing that gave her relief from her debilitating and crippling arthritis, gastrointestinal pain, and insomnia. After her hospitalization, she had to stop her cannabis use and revert to the NSAIDs and opioids she’d been using prior to her several years of successful medical cannabis treatment.
For my second patient, the situation was quite different. He’d been using his cannabis for severe chronic pain for several years (after having difficulty with opioids). When he alerted me that he had CHS, he also told me he was willing to put up with these attacks and had developed a routine to deal with the persistent vomiting, because medical cannabis remained otherwise so helpful in alleviating his musculoskeletal pain.
Why might it be that a substance that works so well to mitigate nausea and vomiting in so many clinical situations can have the opposite effect in a small group of patients?
For one thing, it is known that cannabis has a biphasic effect on nausea and vomiting, with low doses preventing nausea and high doses causing it.
We also know that the site of action of cannabis in our bodies includes receptors found in the nervous system and the gut. (2) It’s hypothesized that the activation of those receptors in the GI tract leads to relaxation of the lower esophageal sphincter, decreased GI motility, and gastric emptying, precipitating hyperemesis. (3) Another hypothesis is that stimulation of the cannabis receptors in the blood vessels in the gut causes them to become congested, engorged, which manifests with symptoms of nausea, vomiting, and abdominal pain.
And, while there seems to be a genetic predisposition to CHS, with genetic markers indicating susceptibility to it (4), it’s also been shown that high-frequency users, not genetically predisposed, taking multiple grams/day of THC-predominant material, are also at risk of developing this condition.
Among those patients, 15.6% carried diagnoses of cannabis dependency or addiction, and 56.6% experienced withdrawal symptoms when discontinuing their use. Almost 90% of patients improved after cannabis cessation, most suffering recurrence rapidly only after resumption.
Interestingly, patients find that taking hot showers helps their symptoms (it’s known that THC affects thermoregulation). In fact, more and more physicians have learned that when a patient comes in complaining of severe nausea and abdominal pain and states that hot showers help them, there’s a good chance that they are suffering from CHS.
Unfortunately, apart from acute treatment with IV fluids, drugs like Haldol, Olanzapine, and benzodiazepines, or using capsaicin on the skin (along with immediate cessation of further cannabis use), there is no other real treatment.
As we inch toward the federal decriminalization of cannabis, CHS prevalence will continue to rise, in parallel with increasing worldwide cannabis use and potency of products. There is a need for education of the general public and my medical colleagues about recognizing the symptoms and causes of CHS, especially in those with a genetic predisposition. Hopefully, as well, we can combat the trend among growers, producers, and consumers to seek higher and higher doses of THC.
Unfortunately, we never saw that first patient after the entity of CHS and its (limited) treatment options became known to us. I can only hope that perhaps someone saw the connection between his heavy cannabis habit and his debilitating symptoms and helped guide him away from his ongoing use.
