The Rising Trend of Cannabis-Induced Vomiting Syndrome in the US
A rare but increasingly prevalent condition linked to chronic cannabis use is causing concern among healthcare professionals in the United States. Known as cannabinoid hyperemesis syndrome (CHS), this condition is characterized by severe and cyclical episodes of uncontrollable nausea, abdominal pain, and vomiting.
The first case of CHS in the US was reported in 2009, and until recently, it lacked a national diagnostic code, making it challenging to track. Emergency department visits are crucial for identifying affected individuals and understanding the underlying causes.
Between 2016 and 2022, researchers at the University of Illinois Chicago observed a significant increase in CHS-related emergency department visits, rising from approximately 4 visits per 100,000 people to 22 visits per 100,000. While CHS remains rare, this trend warrants attention, especially given the potential for symptom relief.
It's important to note that frequent cannabis use does not inevitably lead to CHS. The reasons why a small percentage of cannabis users develop CHS are still unknown, but it is associated with regular use, particularly among younger individuals. The syndrome typically progresses gradually over the first few years after initial cannabis consumption, starting with morning nausea or abdominal pain, and can persist for years.
The more severe stage of CHS occurs when patients experience overwhelming and recurrent vomiting and nausea for a day or two after cannabis use. Interestingly, a hot bath or shower can provide temporary relief from these symptoms.
The use of cannabis can be halted to resolve the condition. During the COVID-19 pandemic from 2020 to 2021, researchers James Swartz and Dana Franceschini found that CHS prevalence in US emergency departments increased significantly. Their analysis of approximately 806 million ER visits nationwide during this period revealed that CHS was most commonly diagnosed in individuals around 30 years old, with slightly more female cases than male cases. The condition was more prevalent in the West and Northeast compared to the South.
The reasons for this increase are still unclear. Swartz and Franceschini suggest that the COVID-19 pandemic likely played a role in the recent rise in CHS through stress, isolation, and increased cannabis use. However, other researchers argue that the higher percentage of diagnoses may not be due to increased cannabis use but rather improved recognition of CHS and a publication bias for a newly recognized syndrome.
In the past, CHS has been described as 'rare but relevant' and often misunderstood. Some published case studies report that it takes up to 17 hospital admissions to receive a diagnosis, and patients have been accused of exaggerating their symptoms. Diagnosing CHS requires ruling out other possible explanations, and cannabis use is a crucial factor in the diagnostic process, even though some physicians may not consider it or patients may be reluctant to disclose their usage.
The absence of a clear rise in CHS before 2020, despite expanding cannabis legalization and the availability of high-potency products, presents a paradox. Swartz and Franceschini suggest that underdiagnosis or misclassification before the syndrome gained broader clinical recognition could be a factor. The post-2020 surge may reflect both increased exposure and heightened diagnostic vigilance.
Further research and better diagnostics are necessary to determine the true rarity of CHS. The study was published in JAMA Network Open.
