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Cannabinoid Hyperemesis Syndrome: Understanding the Basics

According to historical records, marijuana started growing in popularity in the 1910s. Now, it is the third most popular drug in the United States (just behind alcohol and tobacco). National surveys reveal its prevalence. About 18% of the U.S. population, or 48.2 million people, reported using the drug at least once in 2019, while about 22.2 million people use it every month.

Frequent use has the potential to have medical consequences. Recent research shows that about 3 in every 10 marijuana users end up with marijuana-related disorders such as Cannabinoid Hyperemesis Syndrome (CHS). Furthermore, marijuana users under 18 years, are especially vulnerable to marijuana-related disorders.

Most CHS patients acknowledge smoking marijuana 3-5 times daily, long-term despite their pleasure being followed by symptoms of CHS which include repeated, severe, and prolonged instances of vomiting and stomach pain. Many CHS sufferers imprudently increased cannabis use, wrongly assuming that it would relieve symptoms. This conclusion, however, only aggravates symptoms.

Given that marijuana use remains somewhat taboo, some chose not to seek medical attention, thus leaving them untreated.

First Known Cases

CHS was first documented by a team of doctors in South Australia, in 2004. The sample size included 19 patients hospitalized due to cyclical vomiting after chronic cannabis abuse. During the observations, patients were asked to abstain from use and follow up with regularly to ensure compliance. Doctors compared the condition with a published case of psychogenic vomiting. It was observed that after ceasing cannabis use, the cyclical vomiting stopped. Of further note, the patients that temporarily stopped but later restarted saw a return in the bouts of vomiting. This led doctors to conclude that chronic cannabis abuse caused a cyclical vomiting illness in all the patients studied. The illness was identified as CHS. Until 2012, just 33 cases of CHS were published globally.

Symptoms of CHS

CHS is a rare illness caused by the persistent use of cannabis over the course of years. Primary symptoms include:

· Repeated, severe and persistent nausea

· Retching

· Severe, prolonged, cyclical vomiting – up to 5 times an hour

· Extensive, severe stomach pain

· Weight loss

· Dehydration through prolonged vomiting. Severe dehydration can cause additional symptoms such as headache, delirium, confusion, dizziness, fatigue, inexplicable drowsiness, dry mouth, quickened heart rate, flushed skin, chills, swollen feet, rapid breathing, fainting, muscle cramps, and kidney problems.

· Esophagitis. Which leads to difficulty swallowing, pain, heartburn, and acid regurgitation.

Alleviation of Symptoms

Although there have been relatively few documented cases of CHS, a variety of different approaches have been used to ease the symptoms. For example, warm baths/showers, medications to reduce nausea, such as haloperidol, and even antipsychotic drugs. However, for long-term relief, patients are encouraged to stop using marijuana. Studies have shown that 70% of patients who gave up cannabis were cured of CHS while the 30% who did not give up, continued to experience CHS symptoms.

Causes of CHS

Since its first identification in 2004, studies have emerged to study this syndrome. With limited data, and difficulty with follow-up (considering that it is an illicit substance), there is inevitably no consensus on why CHS brings such harsh and extreme symptoms only to some cannabis users.

Nevertheless, there is a consensus that CHS is a rare occurrence that only happens to some people who heavily and consistently use marijuana.

Some scientists theorize that while cannabis gives people relief from nausea by activating certain sections of the central nervous system, that same mechanism can bring about gastrointestinal reactions to create the opposite effect, ultimately leading to CHS. It is quite paradoxical and a curious dilemma. Other factors contributing to CHS could include blocking of gastric acid secretion, slowing down gastric discharging, and irritation and soreness in the area - the exact opposite of what the user desires to achieve.

Research on CHS

The present diagnosis of CHS is based on Rome IV criteria, released in May 2016. Rome criteria is used to diagnose and classify functional gastrointestinal disorders. Information currently available on CHS is largely based on observation and it is difficult to follow up with patients. Therefore, CHS is known as a “poorly understood condition.” However, there is future research in the works for CHS that focuses on pathophysiology, clinical presentation, and natural history.

Discovery of Genetic Link to CHS

Researchers are engaged in trying to find genetic markers that could lead to a diagnosis of CHS. One pioneer in cannabis research, Dr. Ethan Russo says that CHS is not so much a “functional gastrointestinal disorder” as a “manifestation of gene and environmental interaction in a rare genetic disease, unmasked by excessive THC exposure.” The mutation of one or more of the following genes could be the cause of CHS. Here is just a brief overview:

· Catechol-O-methyltransferase (COMT) gene - 56% of the CHS patients in Dr. Russo’s study had COMT gene mutations. This gene is responsible for the production of enzymes that help break down dopamine in the brain.

· Transient Receptor Potential vanilloid subfamily, member 1 (TRPV1) gene - 71% of CHS patients in Russo’s study had mutations of the TRPV1 gene. This gene plays a role in digestion as activation of the stomach’s receptors results in painful, burning sensations, severe pain, and gut disturbances.

· Cytochrome P450 family 2 subfamily C member 9 (CYP2C9) gene - 46% of patients had this gene present. This gene is responsible for breaking down fatty acids. When the body does not rid itself of the THC stored in the body’s fat, the levels can rise such that the body reacts by attempting to purge itself.

· Dopamine Receptor D2 (DRD2) gene - 60% of Russo’s patients had mutations in DRD2. This gene creates dopamine receptor D2 which is known to cause nausea and vomiting.

High THC Contributing Factor

Tetrahydrocannabinol (THC) is the psychoactive chemical in cannabis that alters a user’s mental state by modifying the activity of the brain and nervous system. It produces the “high” that users seek from marijuana. The THC percentage in the cannabis flower ranges from 1% to over 30%. Less than 10% THC is considered low, 10-20% is considered medium, 20-30% is considered high and over 30% is considered very high. Higher THC counts are believed to be a contributing factor in CHS although more research is needed for definitive conclusions.

Ingesting Other Cannabinoids

Cannabinoids acquired from the resin-rich buds of cannabis plants are known as phytocannabinoids. While the most widely used form of intake is smoking, there are several other ways to commit the drug into the system. These include edibles, pills, capsules, tablets, powders, and tinctures. While edibles can include THC, the latter forms are typically CBD products, especially if they are sold in stores. There is currently no research on the severity of CHS when users combine smoking with these other forms of intake.

Cannabinoids linked to CHS

Although the reason for the onset of CHS is not totally understood, it could be connected to the effects of three components of cannabis: tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabigerol (CBG). THC, CBD, and CBG all function in the brain and gut. When it comes to the brain, they have powerful anti-nauseous effects. In the digestive system, the same chemicals bring on nausea and vomiting, although they are assumed to be “overridden” by the anti-nauseous chemical reactions in the brain. CBD and CBG could likely lead to CHS as the absence of same when THC, does not show a link to CHS.

How to Get Help for CHS

As doctors have inadequate knowledge of CHS, there are no clinical guidelines for resolving the syndrome. Patients can be misdiagnosed for years, resulting in delayed treatment.

However, doctors recommend restoring hydration through intravenous fluid replacement, controlling nausea and vomiting by using benzodiazepines such as lorazepam, and proton-pump inhibitors to treat stomach inflammation. Further, the common-sense remedy is to stop marijuana use completely for adequate recovery.

Aside from medical care, CHS has an online support group/community with over 300 members. They provide people with information and a platform for members to share their experiences.

Current Recommendations

Total Abstinence Versus Changing Composition of Cannabinoids

CHS is currently shrouded in mystery and understood very little. Researchers are attempting to figure out why only some marijuana users are vulnerable to CHS, while others remain impervious to the medical condition. Right now, the only known effective treatment for CHS is to stop using cannabis permanently as former users report full recovery from within a few days to a few months. While the chemical composition of cannabinoids can be affected by light, temperature, and acidic conditions, there is not enough information available to adequately predict how these changes might affect a person with CHS.


The connection between CHS and cannabis use was invisible for decades. Even now, many researchers believe that CHS is under-recognized and under-diagnosed. Moreover, emergency room doctors, engage in just a brief interaction with the patient and do not diagnose the patient’s condition as CHS. Further, as the ER never follows up on patients, the opportunity for diagnosis never arises. Moreover, with cannabis still illegal in many states, people may be reluctant to tell their doctors of their addiction to cannabis. Yet, in the end, the doctor needs to know about the symptoms for the patient to recover.


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