Cannabis positivity rates in 17 emergency departments across the United States with varying degrees of marijuana legalization

Nicole V. Tolan, Matthew D. Krasowski, Patrick C. Mathias, Joesph R. Wiencek, Nikolina Babic, Peter R. Chai, Allison B. Chambliss, Ibrahim Choucair, Christiana A. Demetriou, Timothy B. Erickson, Matthew Feldhammer, Deborah French, Bryan D. Hayes, Phillip Kang, Joe M. El-Khoury, Claire E. Knezevic, Andrew Monte, Robert D. Nerenz, Anthony O. Okorodudu, Stephen M. RoperAlec Saitman, Vamsi Thiriveedhi, Sacha N. Uljon, Alexis Vest, Alison Woodworth, Min Yu, Stacy E.F. Melanson

Research output: Contribution to journalArticlepeer-review


Background: Many states in the United States have progressed towards legalization of marijuana including decriminalization, medicinal and/or recreational use. We studied the impact of legalization on cannabis-related emergency department visits in states with varying degrees of legalization. Methods: Seventeen healthcare institutions in fifteen states (California, Colorado, Connecticut, Florida, Iowa, Kentucky, Maryland, Massachusetts, Missouri, New Hampshire, Oregon, South Carolina, Tennessee, Texas, Washington) participated. Cannabinoid immunoassay results and cannabis-related International Classification of Diseases (ninth and tenth versions) codes were obtained for emergency department visits over a 3- to 8-year period during various stages of legalization: no state laws, decriminalized, medical approval before dispensaries, medical dispensaries available, recreational approval before dispensaries and recreational dispensaries available. Trends and monthly rates of cannabinoid immunoassay and cannabis-related International Classification of Diseases code positivity were determined during these legalization periods. Results: For most states, there was a significant increase in both cannabinoid immunoassay and International Classification of Diseases code positivity as legalization progressed; however, positivity rates differed. The availability of dispensaries may impact positivity in states with medical and/or recreational approval. In most states with no laws, there was a significant but smaller increase in cannabinoid immunoassay positivity rates. Conclusions: States may experience an increase in cannabis-related emergency department visits with progression toward marijuana legalization. The differences between states, including those in which no impact was seen, are likely multifactorial and include cultural norms, attitudes of local law enforcement, differing patient populations, legalization in surrounding states, availability of dispensaries, various ordering protocols in the emergency department, and the prevalence of non-regulated cannabis products.

Original languageEnglish (US)
Pages (from-to)248-259
Number of pages12
JournalClinical Toxicology
Issue number4
StatePublished - 2023


  • cannabis
  • decriminalization
  • ICD codes
  • legalization
  • Marijuana
  • recreational use
  • Tetrahydrocannabinol
  • urine drug screen

ASJC Scopus subject areas

  • Toxicology


Dive into the research topics of 'Cannabis positivity rates in 17 emergency departments across the United States with varying degrees of marijuana legalization'. Together they form a unique fingerprint.

Cite this