Study Axes Connection Between Legal Weed and Fewer Opioid Deaths

12 Jun, 2019 Nancy Grover


Sarasota, FL ( – “Cannabinoids have demonstrated therapeutic benefits, but reducing population-level opioid overdose mortality does not appear to be among them.”

That statement from Stanford researchers directly contradicts findings from a 2014 study that suggested states with medical marijuana laws saw fewer opioid deaths. It calls into question the idea that marijuana might be an answer to the unnecessary use of opioids to treat chronic pain.

The researchers from Stanford University’s School of Medicine used the same method that was employed in the 2014 study by the University of Pennsylvania and, in fact, confirmed those findings. However, when they included data on opioid death up to 2017, the results were quite different.

“ …they found the opposite was true. States with legal medical marijuana had a higher rate of deaths due to opioid overdose,” they wrote.

“If you think opening a bunch of dispensaries is going to reduce opioid deaths, you’ll be disappointed,” the study’s senior author, Dr. Keith Humphreys, said in a statement. “We don’t think cannabis is killing people, but we don’t think it’s saving people.”

The study, titled Association Between Medical Cannabis Laws and Opioid Overdose Mortality Has Reversed Over Time, was published by the Proceedings of the National Academy of Sciences of the United States of America.  

The earlier study showed there were on average 25 percent fewer opioid-related deaths in states that had legalized marijuana, which numbered 13 at the time. It included data from the Centers for Disease Control and Prevention from 1999 to 2010.

At the time, many interpreted the results to suggest that legalized marijuana could be one of, if not the answer to using opioids for pain relief.

The Stanford research included CDC data on opioid overdose mortality rates for the next seven years, when many more states had legalized marijuana — for medical and recreational uses.

“Not only did findings from the original analysis not hold over the longer period, but the association between state medical cannabis laws and opioid overdose mortality reversed direction from −21% to +23% and remained positive after accounting for recreational cannabis laws,” the authors wrote.

“We find it unlikely that medical cannabis — used by about 2.5% of the US population — has exerted large conflicting effects on opioid overdose mortality. A more plausible interpretation is that this association is spurious … Research into therapeutic potential of cannabis should continue, but the claim that enacting medical cannabis laws will reduce opioid overdose death should be met with skepticism.”

Humphries speculated that states that had earlier medical marijuana laws tended to be wealthier and more politically liberal and had greater access to addiction treatment. The finding of lower mortality rates “wasn’t about the cannabis, it was something else about those states,” he said.


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    About The Author

    • Nancy Grover

      Nancy Grover is a freelance writer having recently retired as the Director, Media Services for She comes to our company with more than 35 years as a broadcast journalist and communications consultant. Grover’s specialties include insurance, workers’ compensation, financial services, substance abuse, healthcare and disability. For 12 years she served as the Program Chair of the National Workers’ Compensation and Disability Conference® & Expo. A journalism/speech graduate of Ohio Wesleyan University, Grover also holds an MBA from Palm Beach Atlantic University.

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