Use Medical Marijuana? Don’t Drive Under the Influence.

Although many states have legalized marijuana use, that doesn’t make using it safe for the road. However, a new study finds that many medical marijuana users still drive anyway.

The study, published in Drug and Alcohol Dependence this month, highlighted 3 different measures of driving under cannabis influence (1).

Researchers from the University of Michigan Addiction Center surveyed nearly 800 users. Those included people who were seeking certification and recertification for medical cannabis.

The results? In the past 6 months, 56 percent reported driving within 2 hours of using marijuana. In addition, 51 percent reported driving while a “little high,” and 21 percent drove while “very high.”

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“The prevalence of DUIC [driving under influence of cannabis] is concerning, with more research needed on how to best measure DUIC,” the paper states.

Experts know that marijuana can affect coordination and reaction time, corresponding author Dr. Erin E. Bonar told CBS News (2).

Bonar stated: “We just don’t know how long the amount that a person uses is really going to be in their system affecting their driving abilities,” reports CBS News.

Nearly 270,000 people have medical marijuana approval in Michigan, says University of Michigan’s Institute for Healthcare Policy and Innovation (3). That ranks Michigan at second place in the US for number of medical marijuana users.

Bonar says the goal of this study is to keep those users safe on the roads, reports the University of Michigan. According to the author, experts have difficulty finding conclusive guidelines for medical marijuana. That’s largely due to differences in dosing and method of use.

However, the need for clearer guidelines is greater now than ever. In November, recreational use of marijuana became legal in Michigan alongside its previous medical usage, reports the University of Michigan. Now, anyone over age 21 can use the substance in their private residence.

The study’s authors are calling for more research to define parameters for driving and cannabis use. In addition, CBS News reports that researchers are developing new roadside cannabis tests, such as breathalyzers.


  1. Bonar, E. E., Cranford, J. A., Arterberry, B. A., Walton, M. A., Bohnert, K. M., Ilgen, M. A. (2019, January 9). Driving under the influence of cannabis among medical cannabis patients with chronic pain. Drug and Alcohol Dependence. doi:
  2. [CBS Philly]. (2019, January 9). Many Medical Marijuana Patients Driving While High, Study Finds. [Video File]. Retrieved from
  3. Abraham, S. (2019, January 9). New Study Finds Worrisome Statistics Around Medical Cannabis Users Operating Vehicles. University of Michigan Institute for Healthcare Policy and Innovation. Retrieved from