Cannabis-involved self-harm ER visits nearly doubled over 12 years in Ontario, accelerating after medical cannabis liberalization
Cannabis co-involvement in self-harm ER visits increased 90% from 2010 to 2021, with the entire increase after medical cannabis liberalization, while alcohol-involved self-harm declined 17%.
Quick Facts
What This Study Found
Among 158,912 self-harm ER visits, cannabis co-diagnosis increased 90.1% (3.6 to 6.9/100,000) while alcohol declined 17.3%. The entire cannabis increase occurred after medical liberalization (asRR 1.71) with no additional increase during recreational legalization.
Key Numbers
158,912 self-harm visits. 7,810 (4.9%) with cannabis. 24,761 (15.6%) with alcohol. Cannabis: +90.1%. Alcohol: -17.3%. Increase began after medical liberalization (asRR 1.71).
How They Did This
Repeated cross-sectional study using Ontario administrative data (2010-2021). Poisson regression across four cannabis policy periods.
Why This Research Matters
The parallel trends and timing alignment with medical liberalization suggest a real shift in which substances co-occur with self-harm, though whether cannabis is contributing or just more commonly detected remains unclear.
The Bigger Picture
Rising cannabis involvement in self-harm coinciding with declining alcohol involvement suggests the substance landscape around mental health crises is shifting.
What This Study Doesn't Tell Us
Cannot determine causation. Cannabis may cause more self-harm, people at risk may use more cannabis, or clinicians may test more. COVID confounds final period.
Questions This Raises
- ?Is the increase driven by more use, more testing, or genuine causation?
- ?Should cannabis screening become standard in self-harm presentations?
Trust & Context
- Key Stat:
- in cannabis-involved self-harm ER visits from 2010 to 2021, contrasting with 17% decline in alcohol-involved
- Evidence Grade:
- Large population study with clear temporal analysis. Cannot establish whether cannabis is causing more self-harm or is increasingly co-present.
- Study Age:
- 2024 publication using 2010-2021 data.
- Original Title:
- Cannabis-involvement in emergency department visits for self-harm following medical and non-medical cannabis legalization.
- Published In:
- Journal of affective disorders, 351, 853-862 (2024)
- Authors:
- Myran, Daniel T(16), Gaudreault, Adrienne(4), Pugliese, Michael(13), Tanuseputro, Peter, Saunders, Natasha
- Database ID:
- RTHC-05581
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does cannabis increase self-harm risk?
Cannabis is increasingly co-involved in self-harm ER visits, but whether it is causing more self-harm, or people at risk are using more cannabis, or testing is increasing, cannot be determined.
Why did the increase start with medical liberalization?
Medical liberalization increased access and reduced stigma before recreational legalization, suggesting availability and normalization rather than full legalization may be the relevant factor.
Read More on RethinkTHC
- 420-sober-survival-guide
- CBT-cannabis-recovery
- LGBTQ-cannabis-use-recovery-support
- cannabis-induced-psychosis
- cannabis-relapse-cycle-pattern
- cold-turkey-vs-taper-quit-weed
- dating-sober-after-quitting-weed
- exercise-quitting-weed-anxiety-brain
- grieving-quitting-weed-loss
- help-someone-quit-weed
- how-to-quit-weed
- journaling-weed-withdrawal
- marijuana-anonymous-SMART-recovery-compare
- meditation-mindfulness-weed-withdrawal
- online-therapy-cannabis-anxiety-review
- partner-still-smokes-weed
- partner-still-smokes-weed-quitting
- pink-cloud-sobriety-cannabis
- quit-weed-cold-turkey
- quit-weed-or-cut-back-which-is-better
- quit-weed-regret-went-back
- quitting-weed-20s
- quitting-weed-30s
- quitting-weed-adhd
- quitting-weed-after-years
- quitting-weed-depression
- quitting-weed-during-crisis-divorce-job-loss
- quitting-weed-exercise
- quitting-weed-grief-loss-coping
- quitting-weed-legal-state
- quitting-weed-ptsd
- quitting-weed-success-stories
- quitting-weed-triggers-environment
- relapsed-smoking-weed-what-to-do
- relapsed-weed
- self-medicating-with-weed
- should-i-quit-weed
- sober-music-festival-concert-without-weed
- supplements-weed-withdrawal
- telling-friends-quitting-weed
- weed-OCD-intrusive-thoughts
- weed-and-ptsd
- weed-childhood-trauma-ACE
- weed-relapse-prevention-plan
- weed-relapse-why-it-happens
- weed-ritual-replacement
- weed-ruined-relationships
- weed-social-media-triggers-quit
- weed-suicidal-thoughts-withdrawal
Cite This Study
https://rethinkthc.com/research/RTHC-05581APA
Myran, Daniel T; Gaudreault, Adrienne; Pugliese, Michael; Tanuseputro, Peter; Saunders, Natasha. (2024). Cannabis-involvement in emergency department visits for self-harm following medical and non-medical cannabis legalization.. Journal of affective disorders, 351, 853-862. https://doi.org/10.1016/j.jad.2024.01.264
MLA
Myran, Daniel T, et al. "Cannabis-involvement in emergency department visits for self-harm following medical and non-medical cannabis legalization.." Journal of affective disorders, 2024. https://doi.org/10.1016/j.jad.2024.01.264
RethinkTHC
RethinkTHC Research Database. "Cannabis-involvement in emergency department visits for self..." RTHC-05581. Retrieved from https://rethinkthc.com/research/myran-2024-cannabisinvolvement-in-emergency-department
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.