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Understanding Cannabinoid Hyperemesis Syndrome

By Alexander Beadle

Published: Mar 25, 2019   
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Individuals suffering from cannabis hyperemesis syndrome could have more to blame for their condition than just chronic cannabis use, according to a new study. 

The paper, published in the Canadian Journal of Emergency Medicine, studied and compared hair and urine samples from a group of people with cannabis hyperemesis syndrome against similar samples from a control group of frequent cannabis users who did not display symptoms of hyperemesis and a control group representing a more general population. 

The results indicate that the cannabis-related syndrome is not as simple as first thought and more research is required to better understand it. 

Cannabinoid hyperemesis syndrome symptoms

Cannabis hyperemesis syndrome (CHS) is predominantly characterized by chronic cannabis use associated with repeated episodes of vomiting or nausea, sometimes accompanied by a loss of appetite and abdominal pain. In cases where the symptoms are extreme, people with CHS can experience complications related to weight loss and dehydration, such as muscle spasms, seizures, or even kidney failure if symptoms are not properly treated. 

Reported cases of CHS in the medical literature are quite rare, but there is a growing school of thought that believes CHS could be more common than first thought. As a newly recognized syndrome, first formally reported in 2004, it is possible that many clinicians might not be familiar with the syndrome and could be misdiagnosing CHS cases as cyclic vomiting syndrome (CVS), since the two have similar symptoms.

Studying cannabinoid hyperemesis syndrome

In the recent study carried out by researchers from Queen’s University and the Hospital for Sick Children in Ontario, Canada, hair and urine samples were collected from CHS patients who had visited the emergency department for their symptoms.

To be considered for the study, the CHS patients had to have experienced two or more episodes of severe vomiting in the past year and have used cannabis at least three times a week for the last six months. Anyone reporting concurrent synthetic cannabinoid use, opioid use, or alcohol abuse was excluded from the study. Recreational cannabis users with no history of CHS and other emergency department patients who comprised a representative image of the general emergency patient population also contributed samples to form two control groups. 

Samples were taken during an interview one month after the initial emergency room visit to account for the time it takes new hair to appear above the scalp. The urine samples were used to verify self-reported cannabis use, and the hair samples were tested for concentrations of tetrahydrocannabinol (THC), cannabinol (CBN), cannabidiol (CBD) and 11-nor-9-carboxy-THC. The data from the CHS patients was age and sex-matched to members of the two control groups in order to allow a good comparison.

What causes cannabinoid hyperemesis syndrome?

The cause of CHS remains unknown. One theory is that the development of CHS is an eventual and predictable dose-dependent response to the long-term use of increasingly potent cannabis products. Others have speculated that CHS may be the result of an idiosyncratic reaction in a vulnerable subset, similarly to other episodic vomiting conditions, such as hyperemesis gravidarum.

After examining the hair samples in their study, the researchers found that the THC and CBN phytocannabinoid concentrations showed significant overlap between the CHS patients and the two control groups. For the most part CBD and 11-nor-9-carboxy-THC levels in all groups fell below the limit of quantification. 

If the development of CHS was solely down to the chronic use of cannabis, or the long-term use of increasingly potent cannabis products, it would be expected that CHS patients would have far greater concentrations of all cannabinoids in their system than their peers who did not have CHS, but the results from seemed to contradict this theory. Instead, it is more likely that CHS could be driven by a more idiosyncratic mechanism, or at least these results indicate that further research needs to be done into the causes of CHS as it can no longer simply be thought of as a direct consequence of heavy cannabis use.

The researchers noted that heavy cannabis use would indeed still be a necessary factor for developing CHS and so physicians who are treating people with CHS should continue to discourage excessive cannabis use. But this knowledge could be helpful in explaining to patients why they should explore a period of cannabis abstinence to alleviate their symptoms, even if their peers who consume cannabis at the same rate appear to be unaffected by the drug. 

The researchers also detailed two more minor findings. Firstly, the young people in the emergency room control group had higher cannabinoid concentrations in their hair that the older people in the control group. This could indicate that younger people accessing health services are more likely to be regular cannabis users. The hair samples’ high levels of THC were also unexpected when compared to older hair cannabinoid studies. This new THC high is in-keeping with the changing ratios of recreational cannabis, a concerning trend, given the ability of CBD to counter some of the more unpleasant effects of THC.

It is clear that further research into cannabis hyperemesis syndrome is needed as the current understanding of the syndrome appears very limited. But this study demonstrates a positive step towards identifying a root cause for the syndrome. From there, it is hoped that a better understanding of its overall mechanism will follow and perhaps along with it, the development of more comprehensive treatment recommendations for physicians.

Alexander Beadle

Science Writer

Alexander Beadle has been working as a freelance science writer since 2017 and has covered the cannabis industry for Analytical Cannabis since 2018. He has also written for our sister publication, Technology Networks, and the cannabis industry consultant firm Prohibition Partners, among others. Alexander holds a Master's in Materials Chemistry from the University of St. Andrews, where he won a Chemistry Purdie scholarship, and conducted research into zeolite crystal growth mechanisms and the action of single-molecule transistors.


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