What is CHS poisoning? Understanding Cannabinoid Hyperemesis Syndrome

September 21, 2025 •

4 min read

Despite cannabis often being used for its anti-nausea effects, long-term, heavy use can paradoxically lead to a condition known as Cannabinoid Hyperemesis Syndrome (CHS). Commonly referred to as CHS poisoning, this syndrome causes severe and cyclical vomiting that can have significant health consequences if left untreated.

Quick Summary

Cannabinoid Hyperemesis Syndrome (CHS), or 'CHS poisoning,' is a condition causing severe, cyclical bouts of nausea, vomiting, and abdominal pain in chronic, long-term cannabis users. It is not an overdose but a specific reaction to prolonged cannabinoid exposure, often involving compulsive hot water bathing for temporary relief.

Key Points

Not a True Poisoning: CHS is a syndrome resulting from chronic cannabis use, not an acute overdose.
Cyclical Vomiting: The condition is defined by recurring, severe episodes of nausea and vomiting.
Hot Shower Relief: A hallmark symptom is the temporary relief of symptoms by taking hot baths or showers.
Caused by Chronic Use: It only develops in long-term, heavy, and often daily cannabis users, not casual users.
Abstinence is the Cure: The only permanent treatment is the complete cessation of cannabis use.
Often Misdiagnosed: Due to its paradoxical nature, CHS is frequently confused with other gastrointestinal disorders, like Cyclic Vomiting Syndrome.

Demystifying CHS: More Than Just a Bad Trip

While the term 'CHS poisoning' is used by some, it's more accurately described as Cannabinoid Hyperemesis Syndrome, a condition, not a traditional toxic overdose. This syndrome is an emerging public health risk, especially with the increased potency and legalization of cannabis. It affects a subset of long-term cannabis users and is characterized by distinct clinical phases, as detailed in the Rome IV criteria. The diagnosis can be challenging, as symptoms may be misattributed to other gastrointestinal issues or patients may hesitate to disclose their cannabis use.

The Three Phases of CHS

CHS typically progresses through three recognizable phases, each with its own set of symptoms.

The Prodromal Phase

This initial phase can last for months or even years. Symptoms are generally milder and include early morning nausea and a vague, persistent feeling of abdominal discomfort. Many people unknowingly increase their cannabis use during this time, mistakenly thinking it will alleviate the symptoms, which only exacerbates the underlying problem.

The Hyperemetic Phase

This is the most debilitating phase and is characterized by intense, severe, and repeated bouts of vomiting and nausea.

Intense vomiting: Episodes can occur multiple times per hour and lead to extreme distress, pain, and dehydration.
Compulsive hot bathing: A key hallmark of this phase is the urge to take frequent, hot showers or baths, which provides temporary but significant relief from the nausea and abdominal pain.
Dehydration: The constant vomiting can lead to severe dehydration, electrolyte imbalances, and potentially kidney failure.
Abdominal pain: Severe, often diffuse, abdominal pain is common.

The Recovery Phase

The recovery phase begins once the individual stops using cannabis entirely. This is the only definitive cure. Symptoms begin to subside over a few days or weeks, and the individual returns to normal health. However, relapsing into cannabis use will almost certainly trigger another hyperemetic episode.

The Physiological Paradox: Why Cannabis Can Cause Nausea

The exact mechanism of CHS is still under investigation, but it involves the complex interaction between cannabinoids and the body's endocannabinoid system (ECS). While THC can act as an antiemetic (preventing nausea) at low doses, chronic, high-dose exposure seems to have the opposite effect in the digestive tract. Overstimulation and desensitization of cannabinoid receptors, particularly in the gastrointestinal system and parts of the brain that regulate body temperature and vomiting (the hypothalamus), are thought to play a role. The relief from hot showers is also tied to this mechanism, potentially by activating other receptors (TRPV1) that influence the body's temperature and vomiting centers.

CHS vs. Cyclic Vomiting Syndrome (CVS)

It is crucial for medical professionals to differentiate CHS from Cyclic Vomiting Syndrome (CVS), a condition that shares overlapping symptoms but has different triggers and treatments.


Feature	Cannabinoid Hyperemesis Syndrome (CHS)	Cyclic Vomiting Syndrome (CVS)
Trigger	Chronic, long-term, and heavy cannabis use.	Stress, excitement, infections, or a strong migraine history.
Curative Treatment	Complete cessation of cannabis use.	Identification and management of individual triggers.
Hot Showers/Baths	Provides significant, temporary symptom relief.	May also provide relief for some, but not a defining feature.
Pathophysiology	Related to chronic overstimulation of the endocannabinoid system.	Often linked to migraine and central nervous system dysfunction.
Response to Antiemetics	Standard anti-nausea medications are often ineffective during an acute episode.	Standard antiemetics can be effective.

Management and Long-Term Prevention

For an acute hyperemetic episode, hospital care often involves intravenous fluids to combat dehydration and sometimes specialized medications like benzodiazepines or antipsychotics (e.g., haloperidol) that have shown effectiveness where traditional antiemetics fail. Topical capsaicin cream may also be used to help alleviate pain and nausea.

The only long-term solution and preventative measure is complete and sustained abstinence from all cannabinoid products. For many chronic users, this is challenging and may require support from healthcare providers, addiction counseling, or a formal substance use treatment program. Proper diagnosis and patient education are key to breaking the cycle of repeated emergency room visits and misdiagnoses.

For more detailed information on substance use and recovery, visit the Substance Abuse and Mental Health Services Administration (SAMHSA) website.

Conclusion

CHS poisoning, or Cannabinoid Hyperemesis Syndrome, is a serious, paradoxical condition that develops in a subset of heavy cannabis users. Unlike an acute poisoning, it is a cyclical syndrome driven by prolonged cannabinoid exposure. Recognizing the symptoms—including intense vomiting and the urge to take hot showers—is the first step toward a proper diagnosis. The definitive treatment involves total cannabis cessation, which stops the cycle and allows for full recovery. Understanding and accepting this link is crucial for those experiencing these debilitating symptoms, as it can prevent prolonged suffering and potentially serious health complications.

Frequently Asked Questions

CHS poisoning is an informal term for Cannabinoid Hyperemesis Syndrome (CHS). It is a condition in which a long-term, heavy cannabis user experiences cyclical episodes of severe nausea and vomiting. It is not a poisoning in the traditional sense, but a syndrome caused by prolonged exposure to cannabinoids.

CHS affects people who are chronic, long-term cannabis users, typically daily or multiple times per day, often for a period of several years. It is not a universal side effect, and researchers are still working to understand why some users develop it while others do not.

A key feature of CHS is that patients find temporary, significant relief from their nausea and vomiting by taking frequent hot showers or baths. This happens because the heat is thought to help stabilize the part of the brain that regulates body temperature and vomiting, which is disrupted by chronic cannabis use.

Standard anti-nausea medications (antiemetics) are often ineffective at stopping the intense vomiting episodes of CHS. More specialized medications, such as certain antipsychotics and benzodiazepines, are sometimes used in a hospital setting for acute symptom management, but they do not cure the underlying condition.

The only proven and definitive cure for CHS is the complete and sustained cessation of all cannabis use. Symptoms will resolve once the individual stops using cannabis and will not return unless they relapse.

Symptoms typically begin to resolve within a few days or weeks after stopping cannabis use. However, some individuals may experience residual nausea or symptoms for up to a few months. Long-term recovery is dependent on sustained abstinence.

Yes, CHS can be prevented by not using cannabis. For those who already use cannabis, avoiding chronic and heavy use, and seeking help at the first sign of symptoms, can be preventative.