Cannabinoid Hyperemesis Syndrome (CHS): Symptoms, Causes, and the Only Cure

Cannabis is one of the oldest anti-nausea treatments in human history. It is prescribed to chemotherapy patients specifically because it suppresses vomiting. So when chronic, heavy cannabis users start experiencing severe, uncontrollable vomiting that lands them in the emergency room, most doctors do not think to ask about their cannabis use. And most patients do not think to mention it, because why would the thing that stops nausea be the thing causing it.

That paradox is at the center of cannabinoid hyperemesis syndrome, a condition that was first identified in 2004 and is still routinely missed by emergency room physicians. If you are reading this because you have been vomiting for hours and the only thing that helps is a scalding hot shower, this article is going to explain exactly what is happening to you and what you need to do about it.

What CHS Is

Cannabinoid hyperemesis syndrome is a condition in which long-term, heavy cannabis use triggers severe, repeated episodes of nausea, vomiting, and abdominal pain. It was first described in a 2004 study by Dr. J.H. Allen and colleagues, published in the journal Gut (a leading gastroenterology research journal published by the British Medical Journal group). Allen's team identified a pattern in 19 patients who shared three things: chronic heavy cannabis use, cyclical severe vomiting, and a compulsive need to bathe in hot water during episodes.

CHS is not the same as simply feeling nauseous from smoking too much in one sitting. It is a syndrome, meaning it involves a recurring pattern of symptoms that develop over time in response to sustained, heavy use. Most people who develop CHS have been using cannabis daily for years before symptoms appear.

The condition is distinct from cannabis withdrawal syndrome in a critical way. Withdrawal symptoms happen when you stop using cannabis. CHS symptoms happen while you are still using it. In fact, many people with CHS increase their cannabis use trying to treat their nausea, not realizing the cannabis itself is the cause. This makes the cycle worse.

The Paradox: Anti-Nausea Drug Causes Nausea

This is the part that confuses everyone, patients and doctors alike. THC is a proven antiemetic (a substance that prevents vomiting). It works through the CB1 receptors in your brainstem, which regulate nausea and vomiting. In short-term or moderate use, activating these receptors suppresses the vomiting reflex. This is why medical cannabis works for chemotherapy-induced nausea.

But in chronic heavy use, something flips. The current leading theory, supported by a 2012 review by Simonetto and colleagues at the Mayo Clinic published in the journal Mayo Clinic Proceedings (one of the most respected clinical medicine journals in the country), is that prolonged, heavy THC exposure causes a paradoxical effect in the gut. While CB1 receptors in the brain continue suppressing nausea, CB1 receptors in the gastrointestinal tract become dysregulated and begin promoting nausea and slowed gastric motility (the speed at which your stomach empties).

There is also significant evidence pointing to the TRPV1 receptor (transient receptor potential vanilloid 1). This receptor responds to heat and capsaicin (the chemical that makes peppers hot). THC interacts with TRPV1, and chronic exposure appears to desensitize it. When TRPV1 function is impaired in the gut, it disrupts the normal signaling that keeps your digestive system coordinated. This TRPV1 connection also explains why hot water helps, but more on that below.

The short version: cannabis is anti-nausea in your brain but can become pro-nausea in your gut after years of heavy daily use. Your brain and your gut are receiving contradictory signals, and your gut wins.

The Three Phases of CHS

CHS does not appear suddenly. It develops through three distinct phases, and understanding where you are in this progression matters for both diagnosis and treatment.

Phase 1: Prodromal

The prodromal phase is the early warning period. You start experiencing morning nausea, mild abdominal discomfort, and sometimes a fear or anticipation of vomiting. During this phase, most people still maintain a relatively normal eating pattern, though you might notice your appetite is off.

This phase can last months or even years. Because the symptoms are vague and intermittent, most people dismiss them or attribute them to something else. Many people actually increase their cannabis use during this phase because they believe it will help with the nausea. It might temporarily, through the brain-level antiemetic effect, but it is simultaneously making the underlying gut-level problem worse.

Phase 2: Hyperemetic

This is the crisis phase. Nausea escalates into severe, uncontrollable vomiting that can last for hours or days. You may vomit dozens of times per day. The vomiting is often described as violent and relentless. You cannot keep food or fluids down. Abdominal pain can be intense, and weight loss follows quickly.

This is the phase where people end up in the emergency room, sometimes repeatedly. Dehydration becomes a real medical concern. The hyperemetic phase typically lasts 24 to 48 hours in a single episode but recurs in cycles. You might feel fine for days or weeks between episodes, then get hit again. Each cycle tends to become more severe if cannabis use continues.

Phase 3: Recovery

The recovery phase begins when cannabis use stops completely. Symptoms begin improving within 24 to 48 hours and typically resolve fully within one to two weeks. Appetite returns. Vomiting stops. Abdominal pain fades. If you have been through months or years of this cycle, the relief can feel dramatic.

Recovery is complete. CHS does not cause lasting damage to your digestive system as long as you stop using cannabis. However, if you resume use, the syndrome almost always returns, often faster and more severely than before.

The Hot Shower Phenomenon

If there is one thing that makes CHS almost unmistakable, it is this: people with CHS discover that extremely hot showers or baths provide temporary but significant relief from the vomiting and nausea. This is not a mild preference. It becomes compulsive. People with CHS during an active episode will shower for hours, sometimes until the hot water runs out. Some report burning their skin because the water needs to be as hot as possible to provide relief.

This behavior is so specific to CHS that many gastroenterologists now consider it nearly diagnostic. If a patient with cyclical vomiting reports compulsive hot bathing, CHS should be the leading suspect.

The most accepted explanation ties back to the TRPV1 receptor. Hot water activates TRPV1 in the skin, which may temporarily compensate for the TRPV1 dysfunction caused by chronic THC in the gut. Essentially, you are externally stimulating a receptor that cannabis has internally disrupted. The relief is real, but it is temporary. As soon as the hot water stops, the nausea returns.

Capsaicin cream (the same compound that makes chili peppers burn) applied to the abdomen has also shown some effectiveness for the same reason. It activates TRPV1 through the skin. Some emergency departments have started using topical capsaicin as a treatment for acute CHS episodes, though this is still an emerging practice.

Why CHS Is Underdiagnosed

Despite being first described over 20 years ago, CHS remains widely underdiagnosed. There are several reasons for this.

Many doctors have never heard of it. CHS was not covered in most medical school curricula until very recently. A physician who completed training before 2010 may have received zero education on this condition. Emergency room doctors in particular see vomiting patients constantly and are trained to rule out the most common causes first. CHS is not yet on most of those lists.

Patients do not mention cannabis use. In many clinical settings, patients either do not think their cannabis use is relevant to their vomiting or are reluctant to disclose it. Since CHS cannot be diagnosed without knowing the patient's cannabis history, this creates a diagnostic dead end.

It gets misdiagnosed as cyclic vomiting syndrome. Cyclic vomiting syndrome (CVS) is a condition with a nearly identical presentation: recurrent episodes of severe nausea and vomiting. The key difference is that CVS is not caused by cannabis. Many CHS patients carry a CVS diagnosis and have undergone extensive testing, including endoscopies, CT scans, and bloodwork, all of which come back normal. If you have been diagnosed with cyclic vomiting syndrome and you use cannabis daily, it is worth considering that CHS may be the actual cause.

The Simonetto review at Mayo Clinic noted that of the 98 CHS patients they analyzed, the average time from symptom onset to correct diagnosis was years, not months. Many patients had visited the emergency room multiple times and seen multiple specialists before anyone connected their symptoms to cannabis.

Who Is at Risk

CHS does not affect casual or occasional users. The research consistently shows that it develops in people who use cannabis heavily and daily, typically for several years before the first episode. The Allen study and the Simonetto review both found that most CHS patients had been using cannabis daily for at least two years, with many using for a decade or more before symptom onset.

There is no clear threshold for "how much is too much." Individual biology, genetics, and the potency of the cannabis products you use all play a role. But the pattern is consistent: daily, heavy, long-term use is the common denominator. If you are someone who uses cannabis multiple times per day, every day, and you have been doing this for years, you are in the population where CHS develops.

It is also worth noting that CHS appears to be becoming more common. This is likely due to two factors: increasing cannabis potency (today's concentrates and high-THC flower deliver far more THC per session than what was available 20 years ago) and increasing rates of daily cannabis use as legalization expands.

The Only Cure

There is no way to soften this: the only effective treatment for CHS is complete cessation of cannabis. There is no medication that cures it. Switching to a different strain does not help. Reducing the amount does not reliably prevent episodes. CBD-only products have not been shown to resolve CHS. The Simonetto review was unambiguous on this point: patients who stopped cannabis use completely experienced full resolution of symptoms. Patients who continued using experienced continued episodes.

During an active hyperemetic episode, emergency treatment focuses on managing symptoms. IV fluids for dehydration, anti-nausea medications (which often have limited effectiveness in CHS), and in some cases, topical capsaicin. But these are damage control, not treatment. The underlying cause can only be addressed by stopping cannabis.

After cessation, the recovery timeline is relatively fast. Acute vomiting and nausea typically resolve within 24 to 48 hours. Full recovery, meaning complete normalization of appetite and digestive function, usually happens within one to two weeks. For a broader look at what happens when you stop using cannabis, the complete guide to cannabis withdrawal covers the full range of changes you can expect.

You may experience other withdrawal symptoms when you stop, including irritability, insomnia, and anxiety. These are separate from CHS and have their own timeline and trajectory. Having CHS does not exempt you from withdrawal, but it does give you an urgent medical reason to push through it. If you are looking for practical strategies for the quitting process itself, the how to quit weed guide has detailed, evidence-based approaches.

What Happens if You Start Using Again

CHS almost always comes back if you resume cannabis use. And it tends to come back faster and hit harder than the first time. Your body has already demonstrated that it responds to chronic THC with this paradoxical gut reaction. That vulnerability does not disappear with time off. Some people test this by trying to use "moderately" after recovery, and a subset of those people do manage to use occasionally without triggering an episode. But the research does not support this as a reliable strategy, and many people who try it end up back in the emergency room.

This is one of the hardest parts of a CHS diagnosis. If cannabis has been a significant part of your daily life for years, being told you can never use it again is not a small thing. For many people, cannabis was how they managed stress, sleep, pain, or anxiety. Losing that tool requires building new ones. The article on whether weed is addictive covers the psychological and neurological dimensions of cannabis dependence, which may help you understand why quitting feels like more than just a practical decision.

When to Go to the Emergency Room

CHS itself is not fatal, but severe dehydration from prolonged vomiting can become a medical emergency. Go to the emergency room if you experience any of the following during an episode:

• You have not been able to keep any fluids down for more than 12 hours
• You feel dizzy or lightheaded when standing
• Your heart rate is noticeably fast or irregular
• You have not urinated in several hours
• You feel confused or disoriented
• Your vomiting contains blood

Dehydration from CHS can lead to kidney injury, electrolyte imbalances, and in rare cases, esophageal tears from violent vomiting. These are treatable, but they require medical intervention. Do not try to ride out severe dehydration at home.

When to Seek Professional Help

If you have been diagnosed with CHS, or if you suspect you have it, and you are struggling to stop using cannabis on your own, professional support can make a significant difference. CHS gives you a clear, medical, non-negotiable reason to quit. But knowing you need to quit and being able to quit are two different things, especially if you have been using daily for years.

A doctor can help manage the acute episodes and monitor for dehydration and nutritional deficiencies. A therapist or counselor who understands substance use can help you build the coping strategies you will need to replace cannabis in your daily routine.

SAMHSA's National Helpline is free, confidential, and available 24 hours a day, 7 days a week: 1-800-662-4357. They can connect you with local treatment and support resources.

Your Body Is Telling You Something Clear

CHS is one of the few conditions where the body sends an unmistakable signal. The vomiting, the pain, the trips to the emergency room: your body is telling you, in the most forceful way it can, that it cannot tolerate what you are putting into it anymore. That is not a moral judgment. It is physiology. You did not do anything wrong by using cannabis. Your body simply reached a threshold where it can no longer process chronic THC without a severe adverse reaction.

The good news is that CHS is fully reversible. Stop using cannabis, and the symptoms stop. Your digestive system heals. The cycles end. That might sound like an oversimplification when you are in the middle of an episode, hunched over a toilet at 3 AM wondering what is wrong with you. But the answer is clear, the research is consistent, and the recovery is real.

Frequently Asked Questions

Can you get CHS from edibles or concentrates?

How is CHS different from cyclic vomiting syndrome?

Will switching to CBD-only products prevent CHS episodes?

How long after quitting does CHS take to go away?

Can you ever use cannabis again after having CHS?