The Benefits and Consequences of Legalized Marijuana

Moving Towards Full Legalization

Massachusetts legalized medical marijuana in 2013, and the issue of recreational marijuana use will go before voters in 2016.

“If medical marijuana was the midterm exam, we have failed miserably. If full legalization is the final exam, we are definitely not ready,” Kevin P. Hill, MD, director of substance abuse service at McLean Hospital and assistant professor of psychiatry at Harvard Medical School in Boston, told Clinical Pain Advisor.  

Massachusetts law allows quantities of marijuana that are much too high, for indications that are not specific, Dr. Hill noted.

As of March 2016, the District of Columbia and 23 other states have legalized medical marijuana. Policies differ by state, and can best be described as extremely varied; possession limits range from 1 to 24 ounces.

Moreover, questions remain as to whether botanically-derived medical marijuana offers clinical benefit over pharmaceutical-grade THC, its active ingredient. Also known as cannabinoids, prescription THC products — dronabinol and nabilone — have been legally available since 1985.

“Many doctors see the whole medical marijuana movement as a scam. They don’t see enough evidence to support it. On the other hand, we only have two cannabinoids — and there are over 80 cannabinoids in marijuana smoke,” Dr Hill pointed out.

According to the National Cancer Institute, several controlled trials support the use of cannabinoids for nausea and vomiting, but there is insufficient evidence to support the use of cannabis.3 In a recent randomized controlled study (N=30), dronabinol provided a longer analgesic effect than smoked marijuana, with lower abuse-related subjective effects.4

Full Impact Still Unknown

The Colorado study focused on hospital discharges and poison control calls, but did not capture the effects of full legalization, including open sale, which went into effect in 2014.

“We now have a cohort of heavy smokers, who smoke from 5 to 10 times per day. Studies of [this population] may give us some valuable data. We also need to study the effects of marijuana legalization on alcohol and other drug abuse. It may be a gateway drug, or it may decrease more dangerous drug abuse. We need the studies,” Dr Davis said.

“Studies will be critical for moving forward. We need a medical marijuana registry. We need prospective evidence on the effect of legalization on substance abuse, overall functional capacity, and hospital care facility use,” Dr Hill added.

Education is Key

According to Dr Hill, many clinicians remain hesitant to prescribe medical marijuana.

“They are understandably afraid. They are afraid of putting their medical licenses on the line for a treatment with limited evidence for effectiveness,” Dr Hill said.

“There may be a whole host of conditions for medical marijuana [but] for now [its] role is limited, and it would be a good idea to try a cannabinoid before resorting to smoked marijuana,” Dr Hill advised.

Still, medical and recreational use of marijuana is expected to rise, and clinicians should be aware of indications, state regulations, and treatment options, Dr Davis pointed out.

Although it may be too late to put the genie back in the bottle when it comes to medical marijuana, only 4 states have full legalization thus far.

“We may still have time to learn enough to do this in a smart way and limit the risks,” Dr Hill said, noting that the Colorado Department of Health has begun issuing public health messages regarding the dangers of underage marijuana use, driving under the influence, and other safety issues.


1. Davis JM, Mendelson B, Berkes JJ, Suleta K, Corsi KF, Booth RE. Public Health Effects of Medical Marijuana Legalization in Colorado. Am J Prev Med. 2016 Mar;50(3):373-9. doi:10.1016/j.amepre.2015.06.034. Epub 2015 Sep 16.

2., Medical Marijuana,

3. National Cancer Institute, Cannabis and cannabinoids-for health professionals (PDQ),

4. Cooper ZD, Comer SD, Haney M. Comparison of the analgesic effects of dronabinol and smoked marijuana in daily marijuana smokers. Neuropsychopharmacology. 2013 Sep;38(10):1984-92. doi: 10.1038/npp.2013.97. Epub 2013 Apr 22.

This article originally appeared on Clinical Pain Advisor