What Is Cannabinoid Hyperemesis Syndrome (CHS)?

Last updated December 23, 2025 | Published on August 1, 2023

For some people, cannabis may alleviate pain and nausea. For others, it can have the opposite effect. In fact, abdominal pain, nausea and repeated vomiting may all be tell-tale signs of cannabinoid hyperemesis syndrome (CHS), a condition known to hit some daily cannabis consumers seemingly out of the blue. Because the symptoms of CHS can be misinterpreted, educating yourself and consulting a healthcare professional are key. Let's look at what cannabinoid hyperemesis syndrome is, what its symptoms are and how to address them.

Cannabinoid hyperemesis syndrome (CHS) and prolonged cannabis use

Cannabinoid hyperemesis syndrome is a condition that some people who regularly consume high-THC cannabis may experience. Its symptoms — mainly nausea, recurrent vomiting and abdominal pain — can occur sporadically, and its triggers are not well known.

According to a 2022 Canadian Medical Association Journal article: “Patients [with CHS] are often misdiagnosed with cyclical vomiting syndrome — both conditions involve abdominal cramping, nausea and repeated severe bouts of vomiting. The main difference is CHS affects patients with a history of daily, long-term cannabis use.”

It may take years of regular cannabis use for CHS symptoms to develop. It may also take a long time to pinpoint CHS as the cause; one U.S. study showed that CHS patients went to the ER 17.9 times on average before being diagnosed with the condition. The only way to definitively diagnose CHS is to see if symptoms resolve after abstaining from cannabis.

The first known cases of CHS were reported in South Australia in 1996. Researchers are still working to understand this condition, and the suddenness of CHS onset — often after years of daily cannabis consumption — has been especially puzzling.

CHS symptoms

Cannabinoid hyperemesis syndrome unfolds in three stages, and each one presents varying symptoms: the prodromal phase, the hyperemetic phase and the recovery phase.

In the prodromal phase, which may last for many months, CHS symptoms include:

• morning nausea
• abdominal pain
• fear of vomiting

CHS symptoms in the hyperemetic phase, which may last 24 to 28 hours, include:

• recurring vomiting episodes
• nausea and dry heaving
• inability to keep down water or food
• weight loss and dehydration from continuous vomiting

The recovery phase of CHS involves stopping all cannabis consumption. Symptoms typically lessen over a period of days or months until they completely go away.

How do you relieve CHS symptoms?

Hot baths and showers have been shown to temporarily reduce the symptoms of recurrent vomiting in people experiencing cannabinoid hyperemesis syndrome. Additionally, the Canadian Medical Association Journal says topical capsaicin cream and certain prescription medications can alleviate symptoms. Consult a healthcare provider for a formal diagnosis and treatment.

What causes cannabinoid hyperemesis syndrome (CHS)?

The known causes of CHS are heavy cannabis consumption daily for a long period of time (a year or more) or regularly consuming products high in THC.

Scientists like Dr. Ethan Russo, a neurologist and medical researcher who has spent nearly three decades investigating cannabis, suspect CHS may be linked to an inability of certain people to metabolize THC. Research suggests that once CHS develops, even small amounts of THC — including very small doses in CBD-dominant products — can trigger a flare-up. Any kind of cannabis product can be a trigger, including joints, edibles and capsules.

Who does CHS affect?

A 2022 Canadian Medical Association Journal article estimates that one in every 200 frequent cannabis consumers between ages 16 and 44 will experience CHS.

Dr. Russo has noticed CHS patients tend to consume cannabis heavily, often products high in THC. In one of his studies, participants consumed an average of four grams of flower material — two to four buds — a day.

After years of heavy consumption, CHS sufferers suddenly begin feeling sick. Dr. Russo is careful to note that CHS is markedly different from vomiting caused by “greening out” or having a negative reaction to too much THC. “It’s only CHS when there is this recurrent nausea, vomiting, abdominal pain and this unusual behaviour of spending hours in the hot shower or bath to reduce symptoms,” he says.

Why does CHS occur in only some cannabis consumers?

In a 2022 paper for the peer-reviewed journal Cannabis and Cannabinoid Research, Dr. Russo and his co-authors argue that mutations in five genes and receptors linked to human metabolism seem to be connected to the condition.

“The vast majority of CHS patients had at least two of these gene mutations, and there were a couple of people who had all five,” says Dr. Russo. He says a cheek-swab test, similar to the kind used in at-home DNA testing, could eventually help detect these mutations.

How can you get diagnosed with CHS?

For most patients, the first step to a CHS diagnosis begins in a doctor’s office or hospital emergency room. Patients arrive needing immediate relief from symptoms, including dehydration, intense abdominal pain, nausea and vomiting — ambiguous symptoms that could be signs of countless illnesses.

Dr. Russo says diagnosing cannabinoid hyperemesis syndrome can be tricky: CHS can be mistaken for another condition such as cyclical vomiting syndrome, or it can be diagnosed too quickly in people who have other health issues.

“That's why it’s necessary to be very thorough in talking to people and analyzing the situation and, if necessary, doing a genomic screening test,” he says.

What should I do if I suspect I have cannabinoid hyperemesis syndrome (CHS) symptoms?

If you consume cannabis often and have stomach pain, vomiting or nausea, stop consuming it for a few days to see if your symptoms improve. This is the easiest way to understand if you might have CHS.

Even small amounts of THC should be avoided, as the threshold for what may trigger a flare-up is not yet known. It’s also not known if CHS can affect people who consume only cannabis without THC (such as CBD products). With that in mind, the best bet is to avoid cannabis altogether.

As for how long to abstain from using cannabis, Dr. Russo says CHS symptoms can linger for a couple of weeks after stopping cannabis. For some people, it may take more than a month to start noticing improvements. For others with CHS, episodes occur every few months, which means it may take longer for symptoms to alleviate.

If your symptoms eventually disappear — and only return when you consume THC — it could very well be CHS. Inform your healthcare provider of any cannabis consumption to help with your diagnosis.

Taking a T-break could be beneficial in understanding your body’s reaction to cannabis and what happens when you abstain from cannabis.

Cannabinoid hyperemesis syndrome (CHS) treatment

Health Canada says many CHS sufferers seem to find temporary relief after a hot shower or bath. Additionally, the Canadian Medical Association Journal says certain prescription medications may alleviate symptoms.

The relief from medications and baths is limited and temporary, however. The only thing that appears to resolve CHS episodes is avoiding cannabis altogether. Clinical evidence and research on CHS demonstrate multiple cases in which symptoms disappeared when cannabis was cut out entirely, only to recur almost immediately after consuming THC — even after years of abstinence.

Choosing not to consume cannabis is the only known treatment for CHS.

For those experiencing severe symptoms of CHS, it is recommended to go to the hospital. In the hospital, you may be treated with:

• IV fluids and electrolytes for dehydration
• symptom relief therapies

Learn more about CHS

Because cannabinoid hyperemesis syndrome was only recently identified, healthcare providers may not be familiar with it. If you are consuming cannabis regularly, it’s important to recognize cannabinoid hyperemesis syndrome symptoms, specifically severe nausea and recurring vomiting. Track your symptoms — if abstaining from THC improves your condition, consider modifying your cannabis consumption.