What Have Been the Public Health Impacts of Cannabis Legalisation in the USA? A Review of Evidence on Adverse and Beneficial Effects

  • Janni LeungEmail author
  • Vivian Chiu
  • Gary C. K. Chan
  • Daniel Stjepanović
  • Wayne D. Hall
Cannabis (A McRae-Clark B Sherman, Section Editors)
Part of the following topical collections:
  1. Topical Collection on Cannabis


Purpose of Review

To summarise empirical research on the adverse and beneficial public health impacts of cannabis legalisation in states in the USA.

Recent Findings

The most consistent finding from surveys of drug use is that the legalisation of medical cannabis has so far not had an effect on rates of use or cannabis use disorders among youth, but it has increased the frequency of use among adult cannabis users. There are conflicting findings on the impact of legalisation of medical and recreational cannabis use on the following: cannabis use disorders in adults, rates of motor vehicle accidents in which the driver was impaired by cannabis, rates of suicide, and opioid-related harms. The legalisation of recreational cannabis use has increased emergency room attendances for cannabis-related medical conditions (acute adverse psychological effects, hyperemesis, and accidental poisoning of children). There is no evidence to date on the impact of medical or recreational legalisation on the prevalence of mental disorders such as psychoses, depression, and anxiety.


There is suggestive evidence that cannabis legalisation is associated with a range of public health consequences. However, current evidence is limited in the capacity to confidently conclude that these changes are the result of cannabis legalisation. The impacts on public health may take some years to become apparent.


Cannabis Marijuana Legalisation Public health Medical marijuana laws Legislation 



CYSAR is supported by Commonwealth funding from the Australian Government provided under the Drug and Alcohol Program. JL is supported by the University of Queensland development fellowship. We thank Research librarian Sarah Yeates for assisting with literature searching, bibliography management, and proof-editing for this review.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no competing interests.

Human and Animal Rights and Informed Consent

This article does not contain any studies with human or animal subjects performed by any of the authors.

Supplementary material

40429_2019_291_MOESM1_ESM.docx (558 kb)
Online Resource 1 (DOCX 557 kb)


Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.The University of QueenslandSt LuciaAustralia

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