Does Medical Marijuana Legalization Affect Other Substance Use?

Office desk with SUBSTANCE ABUSE paperwork and other objects
The National Bureau of Economic Research (NBER) has conducted a comprehensive study on the impact of medical marijuana legalization on the use of other substances. The study found that increased availability of legal marijuana led to a reduction in overall alcohol consumption and binge drinking, as well as a decrease in opioid-related deaths and prescriptions. The report also found that medical marijuana legalization resulted in a decrease in adult cigarette smoking. However, the study found no evidence that medical marijuana legalization led to an increase in the use of harder drugs, such as cocaine.
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“The THC in marijuana causes the ‘high’ and leads to addiction, mental illness, violence, crime, traffic deaths, and many health and social problems.”

That’s a direct quote from a recent paper released by Missouri Medicine, which goes on to cite statistics and examples that paint a dire picture of the consequences of marijuana legalization.

A majority of medical marijuana patients will see this warning as exaggerated fear-mongering, based on both their own and society’s broader experiences with cannabis therapies. Scholarly types might go one step further and subject some of the paper’s assertions to a peer-review process that puts its methodology and conclusions under scrutiny. And as anyone who ever sat through a ‘Statistics 101’ course may recall, numbers can be used to support almost any point of view.

So who should you trust? Is the Missouri paper a scathing exposé or an outlier in the research community?

For clarity on the subject, we can turn to what has been called the “most comprehensive body of work to date” on the effects of marijuana legalization on society. Titled, “The Public Health Effects Of Legalizing Marijuana,” this report comes from the National Bureau of Economic Research (NBER), which is a non-partisan research organization that uses a broad range of scientifically vetted information to identify social and economic trends.

In their own words, the NBER is:

Committed to undertaking and disseminating unbiased economic research among public policymakers, business professionals, and the academic community.

The report referenced above is basically a study of studies, as the authors combed through hundreds of peer-reviewed studies and included only those that adhered to the highest standards of scientific analysis and reporting. Among the topics covered in the report: a detailed section on marijuana legalization’s effect on the consumption of alcohol, tobacco, and illicit drugs.

While the conclusions drawn from the new NBER report are not unique, they do provide a compelling and credible counterpoint to the opening quote from Missouri Medicine.

Marijuana Legalization & Alcohol Consumption

The authors of the NBER report identified 12 studies that were judged most credible on the effects of marijuana legalization and alcohol consumption. Seven of these studies were based on self-reported alcohol consumption, four tracked alcohol sales data, and several included data from alcohol-related hospital admissions and traffic fatalities. In each case, a method known as difference-within-differences modeling was used to draw comparison of behaviors before and after marijuana legalization.

A majority of the studies showed evidence that increased availability of legal marijuana resulted in both a reduction in the overall consumption of alcohol and binge drinking. The generally accepted reasoning for this relationship is that marijuana provides some individuals with a preferred alternative to alcohol.

Some of the specific examples mentioned in the report note:

Marijuana Legalization & Opioid Use

The portion of the NBER report focused on the relationship between marijuana legalization and opioid use identifies two distinct phases in America’s opioid epidemic. It states:

In the first stage, which lasted through 2010, prescription anti-pain medications such as OxyContin and Vicodin were responsible for the majority of deaths; in the second stage, heroin- and fentanyl-related deaths surged, quickly overtaking mortality attributable to prescription opioids.

This distinction helps put some of the report’s subsequent references and conclusions into perspective.

The first – and still most widely quoted – study on the potential role of marijuana as a substitute for opioids was published in 2014. Based on state-level date from 1999 to 2010, the authors report that the adoption of medical marijuana laws resulted in an average 25% decrease in opioid-related mortality.

CannaMD has also reported on this phenomenon, noting that patients in states where medical marijuana was legal were less likely to turn to opioids for pain relief, and that medical marijuana legalization led to decreased opioid use for pain management.

A majority of studies included in the NBER report came to similar conclusions. One study noted that there was an average 11% reduction in opioid deaths in areas where medical marijuana dispensaries opened.

A study of Medicare Part D records from 2010 to 2015 yielded the following conclusions:

  • Medical marijuana adoption was associated with a 4 to 5% reduction in pain-related prescriptions under Medicare Part D
  • The availability of medical cannabis has a significant effect on prescribing patterns and spending under Medicare Part D
  • If all states had adopted dispensary-based medical cannabis laws by 2015, programmatic savings would have been between $1.4 and $1.7 billion

A review of Medicaid records between 2011 and 2016 showed a similar 6% reduction in opioid prescriptions associated with the introduction of medical marijuana.

The NBER report also includes a 2019 study that goes against the grain of previous information, with the headline: “Association Between Medical Cannabis Laws and Opioid Overdose Mortality Has Reversed Over Time.” The authors report that the addition of data on opioid-related deaths through 2017 shows a reversal in the downward trend associated with medical marijuana, and that states in which medical marijuana was legalized after 2010 experienced an average 22% increase in opioid mortality.

There are several variables that critics of this particular study cite as possible confounding factors. First is the increased percentage of opioid fatalities linked to heroin and fentanyl rather than pain pills — as mentioned earlier. Second is the possibility that the increasing severity of the opioid crisis overwhelmed any positive effects of marijuana legalization. In the period analyzed in this study, U.S. opioid-involved overdose deaths increased from just over 21,000 in 2010 to more than 47,000 in 2017.

Marijuana Legalization & Tobacco Use

A 2020 report on the subject from Nicotine and Tobacco Research began by referencing early studies that suggested marijuana use encouraged cigarette smoking or made it more difficult to quit. But in the same paragraph, the authors state that these conclusions were based on small clinical and experimental studies that showed mixed results:

These data are limited in drawing conclusions with relevance for clinical and policy recommendations today because the data are over 10 years old and rapid changes in the legal status of cannabis and the availability of alternative tobacco products have occurred during the past decade.

Common sense would suggest that any meaningful study of marijuana legalization on smoking habits would start with a more precise identification of user groups. A patient who begins legal cannabis therapy for health reasons is not the same as a recreational user who falls into a smoking/drinking/partying lifestyle.

To avoid this type of ambiguity, the new NBER report focuses only on studies that can clearly define and correlate tobacco use patterns as they relate to the medical legalization of marijuana. Six such studies were included based on both relevance and accuracy of methodology. In summarizing the results, the authors state:

Two of these studies found evidence that legalization for medicinal purposes reduces tobacco use, one found evidence that recreational legalization reduces tobacco use, and the remaining three found no evidence of an association between legalization and tobacco use.

The most interesting takeaway comes from a study that the NBER cited as containing the highest quality information in the available literature. This study, published in the American Journal of Health Economics, drew on three separate and detailed databases to conclude that:

  • Medical marijuana legalization leads to a 1 to 1.5 percentage point reduction in adult cigarette smoking
  • Medical marijuana legalization reduces the number of cigarettes consumed by smokers
  • Estimated medical marijuana legalization-induced tobacco-related healthcare cost savings range from $4.6 to $6.9 billion per year

The authors of this study do not attempt to draw any conclusions as to why legalizing marijuana causes these effects. They did include the finding that medical marijuana legalization resulted in a 2 to 3 percentage point increase in adult marijuana consumption. This insight might help add a new piece to the puzzle.

In January of 2023, Chemical Research in Toxicology published a paper under the wonky title: “Inhibition of Nicotine Metabolism by Cannabidiol (CBD) and 7-Hydroxycannabidiol (7-OH-CBD).” A layman’s explanation of this study was subsequently released in Medical Science News, which reports:

A team led by Washington State University researchers tested the effects of CBD and its major metabolite on human liver tissue and cell samples, showing that it inhibited a key enzyme for nicotine metabolism. For the nicotine-addicted, slowing metabolism of the drug could allow them to wait before feeling the need to inhale more of it along with all the other harmful things found in cigarette smoke.

While it is too early to connect the dots, it is interesting to note that the 2 to 3% increase in adult use of medical marijuana roughly correlates to the reported 1 to 1.5 percentage point decrease in adult cigarette smoking. It’s certainly a concept worthy of additional study.

Marijuana Legalization & Other Substances

An additional subsection of the NBER report addressed the validity of the gateway hypothesis which “suggests that legalizing marijuana should, in a causal sense, increase the use of other, harder drugs.” After sorting through the literature, the authors came to two general conclusions. First, that there was evidence that medical marijuana was related to a strong substitution away from a variety of prescription drugs, including sedatives, anti-depressants, and anti-psychotics. And second, that medical marijuana legalization is not associated with an uptick in cocaine use.

Some of the specific conclusions included in the report note:

  • Medical marijuana legalization was associated with reductions in the prescribing of medications for anxiety, depression, nausea, pain, psychosis, seizures, and sleep disorders under Medicare Part D
  • Sales of over-the-counter sleep aids went down in Colorado with the opening of marijuana dispensaries
  • There is no evidence that medical marijuana adoption is associated with cocaine use; some evidence suggests that recreational marijuana laws increase cocaine use, but these estimates are subject to independent variables
  • Legalizing medical marijuana had no appreciable effects on admissions to substance abuse treatment for cocaine or self-reported cocaine use
  • Living near a medical marijuana dispensary does not affect cocaine-related emergency room visits

The NBER report is currently the most comprehensive and up-to-date work on the health and social effects of medical marijuana legalization. As new information on the subject becomes available, CannaMD will continue to provide updates to ensure our patients are provided with the most accurate information.

Updated: February 1, 2024

Article Written By:

Pierce Hoover

Pierce Hoover is a career journalist with more than three decades of experience in print, broadcast and online writing, editing and reporting, with more than 5,000 articles published in national and international print media and online. His focus on medical marijuana therapies mirrors his broader interest in science-based alternative medical practices.


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