Background: Many countries are adopting permissive cannabis laws, including Canada, which legalized recreational cannabis in October 2018. To date, little evidence exists regarding the extent that cannabis legalization affects the prevalence of population-level adverse events.
Objectives: The current study examined trends in the prevalence of adverse events among people who consume cannabis before and after Canada’s legalization of recreational cannabis.
Methods: Data comes from International Cannabis Policy Study survey waves, which were conducted online prior to recreational cannabis legalization in Canada (2018), and in the three following years. Analysis included 18,285 Canadian respondents who reported cannabis use in the past 12-months. Outcomes included types of adverse events experienced from cannabis use, medical help-seeking, and types of products used. Weighted logistic regression models examined differences in help-seeking, emergency room usage, and cannabinoid hyperemesis syndrome across survey years.
Results: Approximately one-third of consumers reported at least one adverse event within the past 12-months, including 5% who sought medical help. Prevalence of seeking help and types of adverse events were similar before and after legalization; however, the proportion seeking help from emergency rooms increased post-legalization (F=2.77, p=.041). Adverse events were associated with various product types. Help-seeking associated with edibles significantly decreased post-legalization (p=.001).
Implications: A substantial proportion of consumers report adverse events, suggesting widespread ‘dosing’ difficulties. This is avoidable and may burden healthcare services. The reduced likelihood of adverse events from edibles may suggest federal product standards’ effectiveness.