I spent a few months recently in Arizona, which allows the sale and use of marijuana for medical purposes, and I was amazed at all the ads for marijuana dispensaries. At present 20 U.S. states and the District of Columbia permit sale of medical marijuana. Two of those states, Colorado and Washington, just this year legalized recreational use of marijuana. A whole nation, Uruguay, may soon take the final step to legalize recreational use. There are good arguments for and against legalization, but the trend is certainly toward allowing legal use, at least in some circumstances.

Having published research articles on the restraining effects of warnings on tobacco and alcohol products, I quickly concluded that states that permit marijuana use ought to require warnings on marijuana products. So I asked a former student of mine, Dr Sally Rooke, to write to the top 30 researchers in the world with regard to the harmful effects of marijuana use to ask them what warning they would recommend. Sally had credibility because she works as a senior research scientist for a marijuana research institute at a prestigious university. Thirteen of the experts responded, and we categorized their susggestions into six categories of health risks. We then worded a warning for each risk. Here are proposed warnings:

1. Using marijuana can increase your risk of driving accidents and accidents in any other activity that requires your full attention and motor skills.

2. Using marijuana can cause lung and heart problems.

3. Avoid using cannabis if you may become pregnant and avoid cannabis use while pregnant, as use may harm the fetus physically and lead to psychopathology later in life.

4. Using marijuana can cause serious harm to your mental health.

5. Using marijuana can lead to dependence and withdrawal.

6. Adolescents using marijuana may experience deficiencies in brain development and more difficulties in succeeding in life.

Do you think these warnings might help restrain potential users of marijuana? Would they affect your thinking about marijuana use? Research findings on tobacco warnings suggest that warnings showing graphically the harm caused by use tends to reduce use, so one might think the same would be true of marijuana warnings.

I spent a few hours this past week writing to governors and health department directors in states that permit medical marijuana use. I recommended mandating warnings and included a copy of our article on the topic. The article is available online. The reference is:

Malouff, J. M., & Rooke, S. E. (2013). Expert-Recommended Warnings for Medical Marijuana. Substance Abuse, 34(2), 92-93.

What are your thoughts about governments allowing use of marijuana for medical purposes? For recreational purposes? Requiring warnings?

John Malouff, PhD, JD
Assoc Prof of Psychology