Identifying and understanding Cannabis Hyperemesis Syndrome in practice

Cannabis hyperemesis syndrome (CHS) is an increasingly seen complication related to regular, long-term use of THC-containing cannabis products. This is likely due to two significant factors: greater availability thanks to commercialization and, secondly, the higher concentration of THC in cannabis products compared with years ago. A senior emergency physician at St. Michael’s Hospital in Toronto recently advised this author that her data estimates two to three per 100,000 Ontarians attend an ER somewhere in the province each month for CHS. In a recent study presented in JAMA Network Open by Myran et al in September, 2022, the incidence of CHS in the study cohort had increased by a factor of 13 times since 2017, particularly since commercialization. Given its potential for harm and for increasing presentations in hospital emergency departments, it makes good sense to be aware of the syndrome and especially its earlier symptomatology. PresentationIt typically presents as recurrent, persistent vomiting associated with abdominal discomfort and nausea. It can develop gradually, going through early phases of morning nausea and abdominal pain for weeks or months before vomiting begins. An unusual finding is that if the person takes a hot shower or bath, or applies a topical heating cream such as capsaicin to the chest, the vomiting is temporarily relieved. The presence of this in the history should make one think of CHS. Mechanism behind CHSThe half life of THC is about 36 hours and thanks to its lipophilic nature, it accumulates in body fat. Consequently, someone ingesting THC regularly (2+ times weekly) will develop significant tissue levels within weeks of use. In a review article in the Canadian Medical Association Journal in March 17, 2015, King C. and Holmes A. indicated there are CB1 receptors in the enteric nervous system that interact with THC. These remote receptors, possibly from constant triggering from THC, or from protective downregulation, seem to be involved in CHS by over-riding input from CB1 receptors in the hypothalamus that control nausea and emesis.Approach to diagnosisIt is important to not assume the symptoms are related to CHS just because one’s patient is known to use cannabis or has had a prior history of CHS. Other causes, such as bowel obstruction, acute pancreatitis, viscus perforation, renal colic, gall bladder disease or vascular causes, even an acute MI, must be considered. As well, a history of taking NSAIDs for example, is important to learn as they could be related to the presenting symptoms. Furthermore, a condition called periodic cyclic vomiting should be considered in the differential diagnosis.ComplicationsMallory-Weiss syndrome is always a risk with severe, intractable vomiting and esophageal perforation has been reported with CHS. Dehydration and electrolyte and pH imbalances are serious complications. Alterations in Ca and Mg levels as well are a cause for concern. It is the opinion of this author that anyone presenting with CHS should be assessed urgently in the emergency department.Treatment The treatment in the ER involves establishing an IV and administering a “cocktail” of antiemetics, including ondansetron and Haldol. The cocktail can have a QT interval lengthening effect and persons about to be treated with antiemetics should have a resting EKG to determine QT interval length. As well, emergency physicians will also apply capsaicin topically to the chest wall in hopes of reducing the emesis intensity, and they may also administer lorazepam for relaxation. If there are significant imbalances in electrolytes or other critical elements, it makes sense to place the patient on a monitor.Treatment includes abstinence from THC and it may take several days to realize improvement, resulting in a more protracted hospital stay. The patient must be very clearly explained the mechanism for this and why it is important to stop THC ingestion for some time, from several weeks to over a month, and if resuming, to use half the dose and less frequently, stopping use if abdominal discomfort begins again. Some people may have to avoid THC cannabis altogether.Challenges to treatment and careCanada’s attitudes towards cannabis use are now very casual. Its use has evolved over numerous decades in a milieu where adverse effects weren’t identified as they are now, particularly given the weaker concentrations of THC in the past. Many cannabis users love their substance, and can remain in denial of any adverse effects of cannabis. They must be advised that switching to different types of cannabis or modes of ingestion won’t make any difference. This messaging should be given in a supportive, clear manner. In spite of this increase in understanding about cannabis, there are people who remain “frequent flyers” to our emergency departments from recurrent use and ignoring medical information and advice. PreventionFamily physicians and nurse practitioners are wonderfully placed to have conversations with their patients at certain times. In counselling one’s patient regarding safe cannabis use, it would be wise to make them aware of this risk factor. Public health authorities or those charged with stewardship of the cannabis retail outlets should provide readily accessible, clear information regarding this potentially harmful risk at the retail stores.Unfortunately, in some jurisdictions such as Ontario, this information seems to be absent in the retail outlets. This needs to be addressed. Reduction of the incidence of CHS will result in better health outcomes for people and will dramatically reduce the stress on emergency room personnel, not to mention the potential savings to the health care system.Dr. Tom Bell is a medical advisor with the Schizophrenia Society of Canada.

Identifying and understanding Cannabis Hyperemesis Syndrome in practice

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