Changes in Cannabis Potency Over the Last 2 Decades (1995–2014): Analysis of Current Data in the United States



      Marijuana is the most widely used illicit drug in the United States and all over the world. Reports indicate that the potency of cannabis preparation has been increasing. This report examines the concentration of cannabinoids in illicit cannabis products seized by the U.S. Drug Enforcement Administration over the last 2 decades, with particular emphasis on Δ9-tetrahydrocannabinol and cannabidiol.


      Samples in this report were received over time from materials confiscated by the Drug Enforcement Administration and processed for analysis using a validated gas chromatography with flame ionization detector method.


      Between January 1, 1995, and December 31, 2014, 38,681 samples of cannabis preparations were received and analyzed. The data showed that although the number of marijuana samples seized over the last 4 years has declined, the number of sinsemilla samples has increased. Overall, the potency of illicit cannabis plant material has consistently increased over time since 1995 from ~4% in 1995 to ~12% in 2014. The cannabidiol content has decreased on average from ~.28% in 2001 to <.15% in 2014, resulting in a change in the ratio of Δ9-tetrahydrocannabinol to cannabidiol from 14 times in 1995 to ~80 times in 2014.


      There is a shift in the production of illicit cannabis plant material from regular marijuana to sinsemilla. This increase in potency poses higher risk of cannabis use, particularly among adolescents.


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        • ElSohly M.A.
        • Holley J.H.
        • Lewis G.S.
        • Russell M.H.
        • Turner C.E.
        Constituents of cannabis sativa L. XXIV: The potency of confiscated marijuana, hashish, and hash oil over a ten-year period.
        J Forensic Sci. 1984; 29: 500-514
        • ElSohly M.A.
        • Ross S.A.
        • Mehmedic Z.
        • Arafat R.
        • Yi B.
        • Banahan B.F.
        Potency trends of Δ9-THC and other cannabinoids in confiscated marijuana from 1980-1997.
        J Forensic Sci. 2000; 45: 24-30
        • Mehmedic Z.
        • Chandra S.
        • Slade D.
        • Denham H.
        • Foster S.
        • Patel A.S.
        • et al.
        Potency trends of Δ9-THC and other cannabinoids in confiscated cannabis preparations from 1993 to 2008.
        J Forensic Sci. 2010; 55: 1209-1217
        • Slade D.
        • Mehmedic Z.
        • Chandra S.
        • ElSohly M.
        Is cannabis becoming more potent?.
        in: Castle D. Murray R.M. D’Souza D.C. Marijuana and Madness. 2nd ed. Cambridge University Press, Cambridge2012: 35-54
        • ElSohly M.
        • Gul W.
        Constituents of cannabis sativa.
        in: Pertwee R.G. Handbook of Cannabis. Oxford University Press, Oxford2014: 3-22
        • Volkow N.D.
        • Baler R.D.
        • Compton W.M.
        • Weiss S.R.B.
        Adverse health effects of marijuana use.
        N Engl J Med. 2014; 370: 2219-2227
        • Mechoulam R.
        • Carlini E.
        Toward drugs derived from cannabis.
        Naturwissenschaften. 1978; 65: 174-179
        • Cunha J.M.
        • Carlini E.A.
        • Pereira A.E.
        • Ramos O.L.
        • Pimentel C.
        • Gagliardi R.
        • et al.
        Chronic administration of cannabidiol to healthy volunteers and epileptic patients.
        Pharmacology. 1980; 21: 175-185
        • Noonan D.
        Marijuana’s medical future.
        Sci Am. 2015; 312: 32-34
      1. Emergency department visits involving marijuana among adolescents aged 15 to 17: Increase from 2005 to 2010 varied by gender. Data Spotlight. Center for Behavioral Health Statistics and Quality. Drug Abuse Warning Network. November 13, 2012. Available at: Accessed June 8, 2015.