Canadian Centre on Substance Use and Addiction

Understanding Cannabis-Related Physical and Mental Health Presentations to the Emergency Department Following Legalization of Non-Medical Cannabis Use

Tibbo, P., Crocker, C., Emsley, J., Magee, K., Stewart, S., Yakovenko, I., Carter. A, Abidi, S., & Sridharan. S.

This study aimed to determine (i) the frequency of cannabis-related mental and physical health visits to emergency departments (ED) since cannabis legalization in Canada, (ii) the number of such visits required before obtaining a medical admission or mental health referral, (iii) the physical and/or mental health side effects of cannabis use, and (iv) the associations between demographic factors and risks of experiencing cannabis-related health problems. The researchers collected administrative and medical chart data from three of the largest emergency departments in Nova Scotia. The qualitative part of the study (personal interviews) and final data analysis is still ongoing.

Researchers identified that prior to legalization in 2018, there were an average of 120 ED visits per month related to cannabis use, for both medical and mental health issues. Post-legalization, the average number of cannabis-related ED visits increased to 200 per month, with 1.7% of ED encounters being related to cannabis use. The study found that cannabis use disorder in conjunction with a mood disorder significantly increases the risk of self-harm and mortality. Among those who presented with mental health-related complaints, depression/suicidal ideation was the most common. The study found that most patients with mental health complaints were referred to a psychiatric service, but only 25% received a psychiatric emergency consult. More than a quarter of the patients with mental health complaints arrived by police or ambulance, and 54% of the sample was on a psychiatric medication. The researchers highlight that administrative data may underestimate cannabis-related health events. Researchers suggest that knowledge translation efforts should consider the interaction between cannabis and different classes of psychiatric drugs. Recommendations are provided for ED clinicians regarding the importance of informing patients about cannabis use risks. More recommendations are expected once the qualitative part of this study is complete.


Crocker, C. E., Carter, A. J. E., Emsley, J. G., Magee, K., Atkinson, P., & Tibbo, P. G. (2021). When Cannabis Use Goes Wrong: Mental Health Side Effects of Cannabis Use That Present to Emergency Services. Front Psychiatry, 12, 640222.

Crocker, C. E., Emsley, J., & Tibbo, P. G. (2023). Mental health adverse events with Cannabis use diagnosed in the Emergency Department: what are we finding now and are our findings accurate? Frontiers in Psychiatry; Addictive Disorders, 14, 1093081.

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