Study: When medical marijuana is legal, prescription drug use declines

In states where medical marijuana is legal, doctors prescribe fewer prescription drugs for conditions like chronic pain, anxiety, and sleep disorders, finds a new study published by researchers at the University of Georgia in Health Affairs.

"Using data on all prescriptions filled by Medicare Part D enrollees from 2010 to 2013," the abstract explains, "we found that the use of prescription drugs for which marijuana could serve as a clinical alternative fell significantly, once a medical marijuana law was implemented."

Although only 17 states had legalized medical marijuana use at the time of the study — today that number has risen to 24 states plus the District of Columbia — the resultant decline in prescription drug use saved Medicare Part D millions each year, rising to $165.2 million by 2013. The researchers estimate if medical marijuana is legalized nationwide, those savings could increase to $468.1 million annually, or about 0.5 percent of Medicare drug spending as of 2013.