Cannabis-related hospital visits were followed by a 5-fold increase in self-harm and 9-fold increase in suicide risk
In an Ontario population study of over 11 million people, those with cannabis-related hospital contacts had a 5.4-fold increased risk of deliberate self-harm and 9.2-fold increased risk of suicide death within 3 years.
Quick Facts
What This Study Found
Cannabis-related hospital contact was associated with a 5.35x risk of deliberate self-harm and 9.22x risk of death by suicide compared to the general population. Even after excluding those with co-morbid mental health or substance use disorders, self-harm risk remained elevated at 7.18x.
Key Numbers
11,320,897 followed. 85,108 (0.75%) had cannabis-related hospital contacts. Self-harm aHR: 5.35. Suicide death aHR: 9.22. Without mental health comorbidity: self-harm aHR: 7.18. Median follow-up: 5 years.
How They Did This
Population-level retrospective study of 11,320,897 people in Ontario, Canada. 85,108 with incident cannabis-related ED visits or hospitalizations were matched with general population controls. Adjusted hazard models controlled for sociodemographics, mental health comorbidities, chronic conditions, and substance use.
Why This Research Matters
This is one of the largest population studies linking cannabis-related hospital contacts to subsequent self-harm and suicide. The finding that risk persists even without pre-existing mental health conditions suggests cannabis-related hospital visits should trigger mental health screening.
The Bigger Picture
As cannabis use disorder prevalence grows globally, these findings have implications for emergency department protocols. Identifying cannabis-related visits as a potential marker for suicide risk could enable preventive interventions.
What This Study Doesn't Tell Us
Hospital contacts capture severe or problematic use, not typical cannabis use. Residual confounding from unmeasured factors is likely. Cannot determine causation.
Questions This Raises
- ?Would routine mental health screening after cannabis-related ED visits reduce subsequent self-harm?
- ?Is the association causal or does it reflect shared vulnerability?
Trust & Context
- Key Stat:
- 9.2x increased risk of suicide death within 3 years of cannabis-related hospital contact
- Evidence Grade:
- Massive population-level study with comprehensive matching and sensitivity analyses. However, hospital contacts represent the severe end of cannabis use.
- Study Age:
- Published in 2025.
- Original Title:
- Deliberate self-harm and suicide in individuals with cannabis-related hospital contacts in Ontario, Canada.
- Published In:
- Molecular psychiatry (2025)
- Authors:
- Fabiano, Nicholas, Vargatoth, Emi, Pugliese, Michael(13), MacDonald-Spracklin, Rachael, Willows, Melanie, Solmi, Marco, Myran, Daniel T
- Database ID:
- RTHC-06427
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does cannabis use increase suicide risk?
This study found that people who had cannabis-related hospital visits had a 9.2x higher risk of dying by suicide. However, these visits represent severe or problematic use, not typical cannabis consumption.
Was the risk only in people with existing mental health conditions?
No. Even after excluding people with diagnosed mental health or substance use disorders, the self-harm risk remained 7.2x higher.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-06427APA
Fabiano, Nicholas; Vargatoth, Emi; Pugliese, Michael; MacDonald-Spracklin, Rachael; Willows, Melanie; Solmi, Marco; Myran, Daniel T. (2025). Deliberate self-harm and suicide in individuals with cannabis-related hospital contacts in Ontario, Canada.. Molecular psychiatry. https://doi.org/10.1038/s41380-025-03339-9
MLA
Fabiano, Nicholas, et al. "Deliberate self-harm and suicide in individuals with cannabis-related hospital contacts in Ontario, Canada.." Molecular psychiatry, 2025. https://doi.org/10.1038/s41380-025-03339-9
RethinkTHC
RethinkTHC Research Database. "Deliberate self-harm and suicide in individuals with cannabi..." RTHC-06427. Retrieved from https://rethinkthc.com/research/fabiano-2025-deliberate-selfharm-and-suicide
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.