A new study says over half of patients taking medical marijuana for chronic pain in Michigan say they have driven while a "little high."

The study by researchers from the University of Michigan Addiction Center can be viewed at Science Direct. 790 adults were surveyed from February 2014 through June 2015 at Michigan medical cannabis clinics. Results show:

  • 56.4 percent say they drove within two hours of marijuana use.
  • 50.5 percent drove while a "little high."
  • 21.1 percent drove while "very high."
  • Binge drinking was associated with greater amounts of marijuana use.
  • Patients with higher levels of pain were less likely to drive under the influence.

The study is sure to raise concerns with Michigan's recent approval of recreational marijuana use.

When is it safe for marijuana users to drive?

Erin E. Bonar, Ph.D, the lead researcher of the University of Michigan Addiction Center study, says, "The safest strategy is to not drive at all on the day you used marijuana."