Cannabinoid Hyperemesis Syndrome: the cannabis-related condition most clinicians still miss

Cannabis is often discussed in either-or terms — either a benign plant or a public-health threat. The reality, as with most substances, is more textured. One of the textured pieces is a condition called cannabinoid hyperemesis syndrome, or CHS, and it has been quietly bringing long-term cannabis users into emergency rooms in growing numbers for more than a decade.

This is today’s substance spotlight: what CHS is, what we now understand about the biology, and why the treatment picture is both narrow and clear.

The clinical picture

CHS shows up as cyclic, severe nausea, vomiting, and abdominal pain in someone who has used cannabis regularly — often daily — for years. The episodes come in waves, separated by symptom-free intervals. Two pattern features clinicians have learned to look for: symptoms that are weirdly, dramatically relieved by very hot showers or baths, and a relentless cycle that returns no matter what antiemetics are prescribed, until cannabis use stops entirely.

Because the connection to cannabis can feel counterintuitive — many users have relied on it for nausea relief in other contexts — CHS is often missed for years. Patients accumulate ER visits, gastroenterology workups, and sometimes invasive procedures before the diagnosis lands. Cleveland Clinic and other major centers now publish patient-facing CHS explainers specifically to shorten that diagnostic delay.

The biology, as of 2026

Recent reviews in JAMA and elsewhere converge on two pathways. The first is the endocannabinoid system itself: chronic, high-dose exposure to exogenous cannabinoids appears to dysregulate the body’s own cannabinoid signaling, including in the gut and the area of the brainstem that controls vomiting. The second is the transient receptor potential vanilloid-1 (TRPV1) channel — the same heat-sensing channel that capsaicin (the active compound in chili peppers) activates. That overlap is almost certainly why hot showers and topical capsaicin help: they engage TRPV1 in a way that appears to short-circuit the vomiting reflex.

Preliminary genetic work has flagged polymorphisms in COMT, ABCA1, TRPV1, DRD2, and CYP2C9 as candidate susceptibility markers, which would help explain why CHS develops in some long-term users and not others. None of those findings are yet strong enough to drive clinical screening, but they are reshaping the research agenda.

Where the field disagrees

There is no FDA-approved therapy for CHS. The clinical consensus is that cessation of cannabis use is the only definitive treatment. Where clinicians disagree is about everything before that: how much of the symptom burden is best addressed with capsaicin cream versus IV haloperidol or droperidol, how to support patients through what is often a difficult period of cannabis cessation, and how to integrate substance use treatment into ED encounters that are usually structured as one-off acute visits.

There is also active disagreement about whether legalization-era increases in cannabis potency are accelerating CHS prevalence. Anecdotally, many emergency physicians say yes; the published epidemiology is still catching up.

Why this matters for people in recovery

If you’ve been in and out of emergency rooms with cyclic vomiting and a long history of cannabis use, this is worth raising with a clinician you trust. CHS is real, the treatment is real, and the relief can be real — but it requires stopping cannabis, which for many people means navigating a cannabis use disorder they didn’t realize they had.

If that’s where you are, Rize Recovery can help you find evidence-based options in Arizona for cannabis use disorder, including outpatient counseling, motivational interviewing, and peer support. You don’t have to navigate this part alone.

If you are in crisis, please call or text 988.