I was looking at the new Center for Disease Control and Preventions  report on opioid prescriptions and I immediately noticed an interesting correlation. States with medical marijuana laws on average had noticeably lower rates of prescriptions for opioid pain relievers than states without medical marijuana.

Since the CDC data was from 2012 I looked at the 16 states plus D.C. which adopted medical marijuana laws before the beginning of 2012. Of these 17 jurisdictions 12 had below average opioid pain reliever prescription rates.

The only medical marijuana state that was in the top ten for highest rate of opioid pain reliever prescriptions was Michigan at spot number ten. On the other hand five of the top ten states with the lowest rate have medical marijuana laws.

Studies have indicated medical marijuana can help will pain management and allow people with chronic pain to take fewer opioids. Medical marijuana is often recommended as an alternative for pain in some states.

Of course correlation doesn’t necessarily mean there is causation. It is possible both are just the result of some third factor. For example Democratic-leaning states are more likely to have approved medical marijuana laws, and more liberal legislatures may also be more willing to adopt new health care regulations. The map of opioid prescriptions rates does bear some resemblance to the 2012 Presidential election map and in general Southern doctors are more likely to write prescriptions for many types of drugs, like antibiotics.

I simply point out this correlation because it seems like a subject that might benefit from further exploration by a dedicated researcher, especially as more states adopt marijuana reforms. I’m personally unaware of any broad analysis looking at medical marijuana’s impact on the overall use of prescription opioid medication in the country, but think it would be interesting.

It could be important because as the CDC report notes, opioid pain relievers were involved in 16,917 overdose deaths in 2011.

Jon Walker is the author of After Legalization: Understanding the future of marijuana policy