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Medical Marijuana Users are More Likely to Use Prescription Drugs Medically and Nonmedically

Caputi, Theodore L., BS; Humphreys, Keith, PhD

doi: 10.1097/ADM.0000000000000405
Original Research

Objectives: Previous studies have found a negative population-level correlation between medical marijuana availability in US states, and trends in medical and nonmedical prescription drug use. These studies have been interpreted as evidence that use of medical marijuana reduces medical and nonmedical prescription drug use. This study evaluates whether medical marijuana use is a risk or protective factor for medical and nonmedical prescription drug use.

Methods: Simulations based upon logistic regression analyses of data from the 2015 National Survey on Drug Use and Health were used to compute associations between medical marijuana use, and medical and nonmedical prescription drug use. Adjusted risk ratios (RRs) were computed with controls added for age, sex, race, health status, family income, and living in a state with legalized medical marijuana.

Results: Medical marijuana users were significantly more likely (RR 1.62, 95% confidence interval [CI] 1.50–1.74) to report medical use of prescription drugs in the past 12 months. Individuals who used medical marijuana were also significantly more likely to report nonmedical use in the past 12 months of any prescription drug (RR 2.12, 95% CI 1.67–2.62), with elevated risks for pain relievers (RR 1.95, 95% CI 1.41–2.62), stimulants (RR 1.86, 95% CI 1.09–3.02), and tranquilizers (RR 2.18, 95% CI 1.45–3.16).

Conclusions: Our findings disconfirm the hypothesis that a population-level negative correlation between medical marijuana use and prescription drug harms occurs because medical marijuana users are less likely to use prescription drugs, either medically or nonmedically. Medical marijuana users should be a target population in efforts to combat nonmedical prescription drug use.

School of Public Health, College of Medicine and Health, University College Cork, Republic of Ireland (TLC); Drug Policy Institute, Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL (TLC); Veterans Affairs Center for Innovation to Implementation, Stanford University, Stanford, CA (KH).

Send correspondence to Theodore L. Caputi, BS, Fourth Floor, Adjoining Campus, Western Gateway Building, Western Road, Cork, Republic of Ireland. E-mail:

Received 11 September, 2017

Accepted 29 January, 2018

Conflicts of interest: TLC was supported by the George J. Mitchell Scholarship of the US-Ireland Alliance. KH was supported by a Senior Career Research Scientist Award from the Veterans Affairs Health Services Research and Development Service and by a grant from Stanford Neurosciences Institute.

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© 2018 American Society of Addiction Medicine