Cannabinoid hyperemesis syndrome (CHS) is more common than most people realize. Among daily cannabis users, roughly 18% report symptoms consistent with CHS, which translates to an estimated 7.2 million U.S. adults. Across the general population, that works out to about a 2.7% national prevalence rate. Cases have been rising steadily, and in states where recreational cannabis is legal, emergency department visits for CHS have doubled.
Prevalence Among Cannabis Users
CHS causes repeated episodes of severe nausea, vomiting, and abdominal pain in people who use cannabis regularly. A nationally representative U.S. survey found that 17.8% of people who used cannabis daily over the past five years reported these symptoms. That figure surprised many clinicians, who had long considered CHS rare or niche. An earlier study from an urban public hospital estimated that roughly 2.75 million Americans may experience a CHS-like phenomenon each year, but the newer national data pushes that number considerably higher, to over 7 million adults.
The discrepancy between those estimates reflects a real problem: CHS is widely underdiagnosed. Many people with milder or less frequent episodes never seek medical care, and those who do often receive a different diagnosis first. For years, the condition flew under the radar simply because most doctors weren’t looking for it.
Rising Cases After Legalization
CHS rates have climbed in lockstep with broader cannabis access. In Colorado, CHS-related emergency visits doubled after the state moved toward legalization in 2009. Nevada saw a similar pattern, with visits jumping from about 1 per 100,000 to 2.2 per 100,000 after legalization. Across the U.S. and Canada between 2017 and 2021, CHS-related emergency visits doubled overall, most commonly among males aged 16 to 34.
The general pattern across states that have legalized recreational cannabis is consistent: hospital presentations for CHS roughly double post-legalization. Since 2009, hospital discharges for compulsive vomiting have increased by about 8% per year nationally. Two factors are likely driving this trend. More people are using cannabis more frequently, and the THC concentration in modern cannabis products has climbed significantly compared to what was available a decade or two ago. Both higher potency and higher frequency of use increase the likelihood of triggering CHS.
How CHS Overlaps With Cyclic Vomiting Syndrome
One reason CHS prevalence is hard to pin down is that it looks almost identical to cyclic vomiting syndrome (CVS), a condition with the same pattern of episodic, severe vomiting but no connection to cannabis. Emergency department data from 2016 to 2022 shows the two diagnoses shifting in opposite directions: CHS visits rose from about 4.4 per 100,000 to over 22 per 100,000, while CVS-only visits declined from 300 to 186 per 100,000. That suggests many cases previously labeled as CVS were likely CHS all along.
Among emergency visits coded as cyclic vomiting, the probability that the patient also received a CHS diagnosis rose from 3.3% in 2019 to a peak of 13.2% in 2021 before settling at 9.7% in 2023. In other words, roughly 1 in 10 patients showing up to the ER with cyclical vomiting now turns out to have CHS. As awareness grows among emergency physicians, the apparent prevalence keeps climbing, not necessarily because more people are getting sick, but because more cases are being correctly identified.
Who Is Most at Risk
CHS tends to develop after years of regular cannabis use, not weeks or months. The typical patient has been using cannabis for about 10 to 12 years before symptoms appear, often starting in adolescence. At minimum, most people who develop CHS have used cannabis at least weekly for more than a year. Daily or near-daily use carries the highest risk, and using high-potency products like concentrates or edibles with elevated THC levels may accelerate the timeline.
The condition is most frequently diagnosed in young men between 16 and 34, which tracks with the demographic group most likely to use cannabis heavily and consistently. But CHS can affect anyone who meets the usage threshold, regardless of age or sex.
How CHS Is Identified
Diagnosing CHS requires meeting a specific set of criteria. The vomiting episodes need to follow a stereotypical, repeating pattern similar to cyclic vomiting syndrome. They must develop after prolonged cannabis use. And, critically, the episodes must resolve when cannabis use stops completely. These criteria need to be present for at least three months, with symptom onset at least six months before diagnosis.
That last criterion, relief with sustained cessation, is what separates CHS from other causes of chronic vomiting. It’s also what makes diagnosis slow in practice. Many patients don’t connect their symptoms to cannabis, especially if they’ve been using it for years without problems. Some are reluctant to disclose their use, and others have been told by friends or online sources that cannabis should help with nausea, not cause it. The result is that people often cycle through multiple ER visits, imaging studies, and specialist referrals before someone asks the right question about their cannabis habits.
Hot showers or baths provide temporary symptom relief for many people with CHS, a pattern distinctive enough that some clinicians use it as an informal diagnostic clue. But the only proven long-term treatment is stopping cannabis use entirely. Symptoms typically resolve within days to weeks of quitting, though they will return if use resumes.