A comprehensive review found legitimate medical evidence for cannabinoids limited to a few indications, noted that legalization states had higher use rates even before legalization, and identified key public health concerns including driving impairment, pediatric exposures, and addiction.
Read this if you are a healthcare provider navigating cannabis legalization or want a balanced overview of the public health implications.
Medical evidence limited to 4 conditions; legalization states had higher use rates even before laws changed.
What the researchers found
This Annual Review of Medicine article assessed the public health landscape of marijuana legalization from a physician perspective.
Medical evidence was limited to HIV/AIDS cachexia, chemotherapy nausea, neuropathic pain, and MS spasticity. Other therapeutic areas showed promise but lacked robust clinical evidence.
Regarding legalization and use prevalence, the review noted that states with legal marijuana had higher use rates, but these higher rates generally existed before legalization, making it difficult to attribute increases to legalization itself.
Key public health concerns included: acute impairment of driving (well documented), unintentional pediatric ingestion of edibles (increasing with legalization), the complex relationship between marijuana and opioid use (some evidence of substitution), and potential increases in dependence/addiction, psychosis, and pulmonary disorders.
The authors called for more research, noting the urgency given the rapidly shifting legal landscape.
Why it matters
As legalization accelerates, physicians face patient questions about cannabis with limited training and evolving evidence. This review provides a balanced framework for clinical decision-making and identifies the public health surveillance priorities that should accompany legalization.
The numbers in context
Four conditions with established medical evidence: HIV cachexia, chemo nausea, neuropathic pain, MS spasticity. Higher use rates in legal states predated legalization. Public health concerns: driving, pediatric exposure, opioid interaction, addiction, psychosis, lung disease.
How the study worked
Comprehensive narrative review published in the Annual Review of Medicine, covering medical evidence, legalization effects on prevalence, and emerging public health concerns.
What this study cannot tell us
Narrative review format. Published in 2016, before several significant regulatory and research developments. The relationship between legalization and prevalence has become clearer since publication. Some public health concerns identified have been partially addressed by subsequent research.
How to read the evidence
Moderate evidence from a comprehensive narrative review in a prestigious medical journal, synthesizing available evidence across multiple domains.
When this study was published
Published in 2016. The legalization landscape and evidence base have evolved substantially since this review.
The bigger picture
The gap between the speed of legalization and the pace of research creates a challenging environment for evidence-based medicine. This review captures that tension and advocates for research to catch up with policy, rather than either embracing or opposing legalization on ideological grounds.
Questions still open
- Has the evidence base for medical cannabis expanded since 2016? Has legalization led to the predicted increases in cannabis use disorder? Have harm reduction strategies (packaging regulations, impaired driving laws) been effective?
Common questions
Does legalization increase marijuana use?
What medical conditions have the best evidence for cannabis?
Read the original research
Marijuana Legalization: Impact on Physicians and Public Health.
Annual review of medicine, 67, 453-66
Citation
Wilkinson, Samuel T; Yarnell, Stephanie; Radhakrishnan, Rajiv; Ball, Samuel A; D'Souza, Deepak Cyril. (2016). Marijuana Legalization: Impact on Physicians and Public Health.. Annual review of medicine, 67, 453-66. https://doi.org/10.1146/annurev-med-050214-013454