Since legalization in Colorado, health consequences observed include psychosis, suicide, other substance abuse, cognitive impairments, fatal motor vehicle collisions, cardiovascular and pulmonary effects, pediatric exposures, contaminant risks, and hash-oil burn injuries.
States considering legalization, public health officials, and cannabis policy researchers.
Psychosis, suicide, and substance abuse are the most concerning post-legalization effects
What the researchers found
The most concerning effects were psychosis, suicide, and other substance abuse. Cognitive impairments may not be reversible with abstinence. Additional concerns include fatal motor vehicle collisions, cardiovascular and pulmonary damage, pediatric exposures, contaminants (infectious agents, heavy metals, pesticides), and hash-oil burns. "Budtenders" provide medical advice without medical training.
Why it matters
Colorado is a real-world natural experiment in cannabis legalization. This review catalogs the negative health consequences that other states should anticipate and prepare for.
The numbers in context
Multiple categories of harm documented. Cannabis research may benefit seizures, MS spasticity, chemo nausea, chronic pain, cardiovascular outcomes, and sleep disorders.
How the study worked
Narrative review of health and safety effects observed in Colorado emergency departments since cannabis legalization.
What this study cannot tell us
Narrative review from one state. No systematic data collection or pre/post comparison. May overrepresent emergency presentations relative to overall population experience.
How to read the evidence
Moderate: comprehensive narrative review of a unique natural experiment, but lacks systematic methodology.
When this study was published
Published in 2019.
The bigger picture
The review presents a balanced view: acknowledging potential medical benefits while documenting significant real-world harms. The lack of standards for cannabis product composition and federal research restrictions are identified as barriers to progress.
Questions still open
- How do other legalized states compare to Colorado? Would stricter product regulations reduce these harms? Can "budtender" advice be regulated or replaced with trained professionals?
Common questions
Does the review say legalization was a mistake?
What are "budtenders"?
Read the original research
Legalized Cannabis in Colorado Emergency Departments: A Cautionary Review of Negative Health and Safety Effects.
The western journal of emergency medicine, 20(4), 557-572
Citation
Roberts, Brad A. (2019). Legalized Cannabis in Colorado Emergency Departments: A Cautionary Review of Negative Health and Safety Effects.. The western journal of emergency medicine, 20(4), 557-572. https://doi.org/10.5811/westjem.2019.4.39935
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