Cannabinoid Hyperemesis Syndrome: What the Evidence Actually Shows

Cannabinoid hyperemesis syndrome, usually shortened to CHS, is a condition of cyclical, often severe nausea and vomiting seen in people who use cannabis heavily and chronically, typically daily or near-daily for months to years. According to PubMed, cyclic vomiting attacks tied to chronic cannabis use were virtually unrecognized in the medical literature until roughly 25 years ago, and the pattern has become far more visible to emergency clinicians as high-potency cannabis use has become more common (Bonnet, 2025, Der Nervenarzt, ^[1]). The classic, distinguishing clue is that hot showers or baths bring temporary relief, which is unusual enough that it is now written into the formal diagnostic criteria for the condition. This page focuses on what recent, peer-reviewed research actually supports about who gets CHS, how it is told apart from similar conditions, why heat helps, and which treatments have real evidence behind them.

Why cannabinoid hyperemesis syndrome ER visits just jumped sharply

According to PubMed, a CDC report published in August 2026 in Morbidity and Mortality Weekly Report analyzed emergency department visit data from the National Syndromic Surveillance Program between January 2023 and May 2026, covering 199,565 ED visits that involved CHS (Vivolo-Kantor et al., 2026, MMWR, ^[2]). Through September 2025, the proportion of ED visits involving CHS stayed roughly steady, at about 3.35 per 10,000 all-cause ED visits. Then, in October 2025, a new CHS-specific diagnosis code went into use, and in that single month the proportion jumped to 11.26 per 10,000 visits. Over the following eight months, the monthly average ran about 3.7 times higher than the pre-code baseline, with the largest increases among people aged 15 to 24 and among females. The CDC authors are careful to note that this abrupt, sustained jump likely reflects clinicians finally having a specific code to document a condition they were already seeing and recognizing more readily, rather than a true multi-fold increase in how many people actually developed CHS that month. Still, the underlying message for anyone searching about CHS right now is straightforward: this is a condition emergency physicians are actively being trained to look for, and it is being diagnosed far more often than it was a year ago.

That points to a real, if slower-moving, upward trend that predates the coding change. According to PubMed, a separate analysis of the Nationwide Emergency Department Sample, covering roughly 85 percent of all U.S. ED visits from 2016 through 2022, found CHS-coded visits rising from 4.4 per 100,000 ED visits in 2016 to a peak of 33.1 per 100,000 in the second quarter of 2020, before settling at a still-elevated 22.3 per 100,000 in 2022 (Swartz and Franceschini, 2025, JAMA Network Open, ^[3]). Over that same period, visits coded as cyclic vomiting syndrome alone, without any cannabis involvement, actually declined, from about 300 to 186 per 100,000 visits, a pattern consistent with cannabis-related cyclic vomiting displacing some of what used to be labeled as unexplained cyclic vomiting. That same study found the highest relative risk of a CHS-coded visit in patients aged 18 to 25 and 26 to 35, and a slightly lower relative risk among females compared with males, a detail worth knowing since it runs against the assumption that the recent surge is being driven mainly by young women.

How CHS is told apart from cyclic vomiting syndrome and other look-alikes

CHS is not simply diagnosed by asking whether someone uses cannabis and vomits. According to PubMed, the current Rome-based diagnostic framework for disorders of gut-brain interaction now formally distinguishes CHS as its own entity within the gastroduodenal disorders category, separate from functional dyspepsia, chronic nausea and vomiting syndrome, gastroparesis, and cyclic vomiting syndrome, with the newest revision (Rome V) aimed specifically at sharpening these distinctions rather than lumping them together as vaguely “functional” (Remes-Troche, 2026, Revista Española de Enfermedades Digestivas, ^[4]). That precision matters clinically, because roughly a third of people diagnosed with cyclic vomiting syndrome also use cannabis chronically, which makes the two conditions genuinely difficult to tell apart at a single emergency visit. According to PubMed, the only reliable way to distinguish true CHS from cannabis use that happens to coexist with cyclic vomiting syndrome is to document full symptom remission during six to twelve months of confirmed cannabis abstinence; short of that, emergency departments generally end up treating a mixed, “suspected CHS” picture rather than a confirmed diagnosis (Bonnet, 2025, Der Nervenarzt, ^[1]). A broader review of the cyclic vomiting syndrome literature adds that CHS is increasingly understood as one of several overlapping endophenotypes of a shared vomiting-disorder spectrum, alongside migraine-associated and autonomic-dysfunction-associated forms, rather than a fully separate disease with its own unique biology (Li, 2025, Neurogastroenterology and Motility, ^[5]). In practice, this means a clinician evaluating unexplained cyclic vomiting should still rule out GERD, gastroparesis, gallbladder disease, and pancreatitis before settling on a cannabis explanation, exactly as the live version of this page already advises.

Why hot showers help, and why that explanation is a leading theory, not a settled fact

The compulsive hot-shower or hot-bath behavior in CHS is distinctive enough that it appears as a supporting diagnostic clue in the Rome-based criteria. The most commonly cited explanation is that tetrahydrocannabinol (THC) activates TRPV1 receptors, the same heat- and capsaicin-sensitive receptors that give chili peppers their burn, and that external heat or capsaicin cream can override that same pathway and blunt the nausea signal. According to PubMed, a 2026 case report describing successful use of topical capsaicin cream for refractory CHS proposes exactly this mechanism, TRPV1 activation followed by peripheral receptor desensitization, as the reason both hot water and capsaicin cream produce relief (Ilyas et al., 2026, Clinical Medicine Insights: Case Reports, ^[6]). But a broader 2025 review of the cyclic vomiting spectrum is more cautious, listing TRPV1 alongside CGRP, mitochondrial dysfunction, and impaired cation transport as “possible,” not confirmed, contributing pathways, distinct from mechanisms it calls fully established, such as CB1 receptor involvement and hypothalamic-pituitary-adrenal axis dysregulation (Li, 2025, Neurogastroenterology and Motility, ^[5]). The honest summary is that TRPV1 is the leading, most mechanistically coherent explanation for why heat helps, and it is consistent with the clinical pattern seen at the bedside, but it has not been proven with the kind of direct human mechanistic study that would settle the question.

What the treatment evidence actually shows

This is the area where the existing coverage of CHS online, including the previous version of this page, tends to overstate certainty. According to PubMed, a 2024 systematic review conducted for the Society for Academic Emergency Medicine’s GRACE initiative searched specifically for direct evidence on treating CHS in the emergency department and found seven qualifying studies covering 492 patients total (Sabbineni et al., 2024, Academic Emergency Medicine, ^[7]). Five of those studies, covering 386 patients, evaluated topical capsaicin cream, and the review’s conclusion is that the evidence for capsaicin is mixed, meaning the existing studies do not consistently agree on whether it meaningfully reduces nausea and vomiting. Two studies, both randomized controlled trials covering 106 patients, evaluated dopamine antagonists, specifically haloperidol and droperidol, and both of those trials found a clinical benefit over usual care or no active comparator, a more consistent signal than what was found for capsaicin. The review’s own conclusion is blunt: because of the small number of studies, small patient numbers, inconsistent dosing protocols, and risk of bias across the available research, “methodologically rigorous trials on both types of intervention are needed” before either can be called a well-established treatment.

That does not mean capsaicin is useless in practice, only that it is not yet proven at the level the underlying evidence review demands. According to PubMed, the same 2026 case report referenced above describes a 28-year-old man with refractory CHS whose retching stopped within 10 minutes and whose abdominal pain resolved by 90 minutes after roughly 2 grams of 0.1 percent topical capsaicin cream was applied to his abdomen in the emergency department, with only transient local burning as a side effect (Ilyas et al., 2026, Clinical Medicine Insights: Case Reports, ^[6]). A 2025 narrative review separately reports that intramuscular haloperidol, at doses up to 5 milligrams, and capsaicin cream at a concentration of 0.075 to 0.1 percent, both provide acute relief in clinical practice, with capsaicin generally acting more slowly than either hot water or haloperidol (Bonnet, 2025, Der Nervenarzt, ^[1]). And a 2026 study of a pediatric emergency department that implemented a standardized CHS treatment algorithm found that, after the algorithm rolled out, capsaicin use rose from 2.7 percent to 22.2 percent of encounters and metoclopramide use rose from 6.8 percent to 42.6 percent, both large, statistically significant shifts in practice, while the average haloperidol dose given fell from 2.7 milligrams to 1.0 milligram (Kelly et al., 2026, Pediatric Emergency Care, ^[8]). Notably, that same study found no statistically significant change in hospital admission rates or ED length of stay after the algorithm was adopted, a reminder that a treatment protocol changing what clinicians reach for is not the same thing as a treatment protocol being proven to shorten a hospital stay. Standard antiemetics such as ondansetron and metoclopramide, along with IV fluids and acid reducers, remain the default first response in most emergency departments, but the clinical literature consistently describes them as frequently insufficient for the nausea and vomiting that CHS specifically produces, which is why dopamine antagonists and capsaicin are being studied as targeted add-ons rather than replacements for supportive care.

What actually resolves CHS, and what is still unproven

Across every source reviewed for this page, one point is consistent and not in dispute: full, sustained cannabis abstinence is the only intervention reliably associated with complete resolution of CHS, and continued or resumed heavy use reliably brings the cycle back, often faster and more intensely than before. According to PubMed, this “sensitization” pattern, in which the threshold for triggering another CHS episode drops after repeated cycles, is specifically described in the clinical literature, meaning a relapse at a lower dose than someone used previously can still provoke a full episode (Bonnet, 2025, Der Nervenarzt, ^[1]). What is not established in the sources reviewed here is whether a gradual taper produces better long-term outcomes than abrupt cessation, or whether switching to CBD-dominant products meaningfully reduces symptoms during that process. Those are reasonable, commonly recommended clinical strategies for supporting a patient through withdrawal and addressing the pain, anxiety, or nausea that may have driven the cannabis use in the first place, but they have not been tested against each other in a controlled study, and this page is not going to present either one as proven superior when the evidence does not yet say so.

The bottom line

Cannabinoid hyperemesis syndrome is being diagnosed far more often than it was even a year ago, partly because of genuinely rising heavy cannabis use and partly because clinicians now have a dedicated code and more training to recognize it. It remains a clinical diagnosis of exclusion, confirmed only by ruling out more common look-alikes like GERD, gastroparesis, and cyclic vomiting syndrome, and, ideally, by documenting that symptoms fully resolve after a sustained period of cannabis abstinence. Hot showers and, per the most direct evidence available, dopamine antagonists like haloperidol appear to offer the most consistent acute relief; capsaicin cream shows real promise in case reports but has genuinely mixed support in the systematic evidence, and standard antiemetics frequently fall short. If you or someone you know is having recurring, unexplained cycles of severe vomiting and heavy cannabis use is part of the picture, that combination is worth raising directly with a physician, by name, rather than waiting to be asked. Sustained abstinence remains the only path to full resolution that the evidence actually supports.

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