Imagine being struck, again and again, by waves of violent vomiting so severe that the only thing that brings any relief is standing under a scalding hot shower for hours at a time. Now imagine visiting the emergency room over and over, undergoing test after test, and still leaving without an answer. This is the reality for a growing number of people living with a puzzling condition called cannabis hyperemesis syndrome, or CHS. Once considered rare, it is now turning up in emergency rooms across the United States and Europe with striking frequency, and doctors are only beginning to catch up.
Here is what you need to know about what causes this syndrome, how to recognize it, how it is diagnosed and treated, and why cases have been climbing so sharply in recent years.
Cannabis hyperemesis syndrome is a condition that affects some people who use cannabis, also known as marijuana, frequently and over a long period of time. It causes repeated episodes of intense nausea, forceful vomiting, and cramping abdominal pain. The word hyperemesis simply means excessive vomiting, and in the most severe cases the vomiting can be so relentless and so accompanied by cries of pain that it has earned a grim nickname among medical staff: scromiting, a blend of screaming and vomiting.
The condition was first described by researchers in Australia in 2004, which makes it a relatively new entry in the medical books. For years it was thought to strike only after roughly ten to twelve years of heavy, chronic use. More recent evidence has upended that assumption, showing that symptoms can begin far sooner, sometimes within the first year of regular use, especially with today's much stronger cannabis products.
The exact cause is still not fully understood, which is part of what makes CHS so tricky. The leading explanation centers on what scientists call the biphasic effect of cannabis. In small or occasional doses, cannabis can actually calm nausea, which is why it has sometimes been used to ease the side effects of chemotherapy. But with frequent, high dose use over a long time, the effect appears to flip. Instead of soothing the system that controls vomiting in the brain, heavy exposure seems to overstimulate and dysregulate it.
Cannabis contains active compounds, the best known being THC, which bind to receptors found throughout the brain and, importantly, throughout the digestive tract as well. Over time this constant stimulation is thought to interfere with how quickly the stomach empties and how the digestive system functions overall. Researchers also point to the overstimulation of certain receptors involved in the body's response to heat and pain, which may help explain one of the syndrome's strangest features. A major driver of the recent rise is potency. The concentration of THC in cannabis products has climbed steadily over the past decade, and higher potency is strongly linked to more frequent use, which is the single biggest risk factor for developing CHS.
CHS tends to unfold in three distinct phases, and recognizing the pattern is often the key to catching it.
The early, or prodromal, phase can last for months or even years. During this stage a person may feel queasy in the mornings, experience a nagging fear of vomiting, and notice mild stomach discomfort. Many people keep using cannabis during this phase, sometimes because they mistakenly believe it will settle their stomach.
The active, or hyperemetic, phase is the crisis point. This is marked by overwhelming nausea and repeated, forceful vomiting that can strike many times in a single hour. Severe abdominal pain, an inability to keep food or fluids down, weight loss, and dangerous dehydration are common. Episodes can last for days. It is during this phase that people most often land in the emergency room.
The recovery phase begins only once cannabis use stops. Symptoms gradually fade, appetite returns, and normal eating resumes, usually over a period of days to weeks.
One of the most distinctive signs of CHS is a compulsive urge to take very hot baths or showers. People often discover on their own that hot water temporarily eases their nausea, and many end up bathing several times a day, sometimes for hours, chasing that relief. Doctors consider this behavior such a strong clue that it can practically point to the diagnosis on its own. There is a real hazard here worth flagging, however. Some sufferers turn the water so hot that they end up with scald burns, so this coping method carries its own risk of injury.
There is no single blood test or scan that confirms cannabis hyperemesis syndrome. It is what physicians call a diagnosis of exclusion, meaning doctors must first rule out other possible causes of the vomiting, from infections to blockages to a closely related condition called cyclical vomiting syndrome, which looks remarkably similar. Doctors weigh several key features together: several years or more of regular cannabis use preceding the illness, a repeating cycle of severe nausea and vomiting, relief from hot bathing, and, most tellingly, symptoms that resolve once cannabis is stopped. Being under the age of 50 is also considered a supporting factor, as is significant weight loss and a tendency for symptoms to be worse in the mornings.
The biggest obstacle to a correct diagnosis is often honesty. Because patients may be reluctant to disclose how much cannabis they use, and because many doctors historically did not think to ask, the condition is frequently missed. One study found that patients averaged nearly 18 emergency room visits and thousands of dollars in tests before the syndrome was finally identified. To help solve this, health authorities took a major step in October 2025, when a specific medical diagnosis code for CHS was introduced for the first time. For the first time, doctors could formally record the condition in a patient's chart, which is already improving how well the illness is tracked.
The rise in cases has been dramatic. One 2025 analysis found that in 2016, only about 4.4 out of every 100,000 emergency department visits were diagnosed as CHS. By 2020 that figure had leapt to 33.1 per 100,000 before settling at 22.3 per 100,000 in 2022. The increase lined up closely with the spread of legalization and was especially sharp during the pandemic years.
The introduction of that new diagnosis code in late 2025 revealed just how badly the condition had been undercounted. According to figures published by the Centers for Disease Control and Prevention in August 2026, nearly 200,000 emergency visits involving CHS were recorded between early 2023 and mid 2026. In the very first month after the new code took effect, the share of emergency visits identified as CHS more than tripled, jumping from about 3.4 per 10,000 visits to over 11 per 10,000. Experts believe this leap reflects better recognition of a condition that was there all along rather than an overnight explosion in cases. Local hotspots have been reported too, with notable spikes in Virginia, Massachusetts, parts of California, and North Carolina, where one hospital official described seeing affected patients almost every day.
Europe is watching the same trend unfold, though its data is patchier. Cannabis use across Europe is estimated at around 8 percent of the population, and the syndrome is increasingly recognized as use climbs. France offers a telling example. It is one of the continent's heaviest cannabis-consuming nations, with roughly 11 percent of the population using it, and a study conducted in Marseille emergency rooms estimated that CHS accounted for about 1.6 percent of patients who arrived with unexplained abdominal pain over a ten month period. Neighboring Canada provides a useful comparison for what legalization can bring. After it legalized cannabis, use among people aged 15 and older rose from 15 percent to 25 percent in just four years, and hospital admissions tied to cannabis doubled.
Perhaps the most consistent finding across all this research is who is most affected. CHS overwhelmingly clusters among younger adults. Multiple studies place the highest concentration of cases among people roughly aged 16 to 35. The CDC's own figures show that emergency visits for the syndrome are by far the most common among those aged 15 to 24, followed closely by the 25 to 34 group. Rates then fall off steeply in older age brackets. Women and younger people have shown some of the biggest increases, mirroring a broader rise in frequent cannabis use among young adults and females.
For readers over 50, this age pattern matters in a particular way. While the syndrome itself is far less common in your own age group, it is precisely the illness that your children and grandchildren may be at risk for and may not recognize. Knowing the telltale signs, the cycle of vomiting, the compulsive hot showers, and the link to regular cannabis use, could help you steer a younger loved one toward the right answer far sooner.
Here is the genuinely good news. Cannabis hyperemesis syndrome is not a lifelong sentence, and it does not typically cause permanent damage when handled properly. The one proven cure is complete and lasting cessation of cannabis use. Once a person stops entirely, symptoms usually clear within days to a few weeks, and the recovery tends to be complete. During an acute episode, treatment focuses on comfort and safety: intravenous fluids to correct dehydration, medications to calm the nausea, and sometimes a short hospital stay for the worst cases.
The catch is that as long as cannabis use continues, the vicious cycle continues with it. People who cut back but do not fully quit often find their symptoms return. There are also real dangers during severe episodes that should not be underestimated, including dangerous dehydration, imbalances in the body's essential minerals, kidney strain, and even tears in the esophagus from the sheer force of the vomiting. In very rare cases, complications have proven fatal. That is why recognizing the condition early, and acting on it, truly matters.
