Unintended Consequences of Legalizing Cannabis for Medical and Recreational Use

Kenny Lin, MD, MPH
Posted on October 29, 2024

A recent study described trends in medical cannabis licensure in 38 states and Washington, DC, from 2020 to 2022. The overall number of enrolled patients increased from 3.1 to 4.1 million, but 13 of the 15 jurisdictions that have legalized recreational use saw decreased enrollment, likely because patients no longer needed a clinician’s authorization to legally purchase cannabis. (In my state of Pennsylvania, where recreational use remains illegal, the prevalence of patients using medical cannabis more than doubled from 236 to 549 per 10,000 people.) Of concern, the percentage of patient-reported qualifying conditions with “substantial or conclusive” evidence supporting benefits of cannabis, as according to the National Academies of Sciences, Engineering, and Medicine, declined from 70% to 54%.

A 2022 Agency for Healthcare Research and Quality review and AFP commentary by Drs. Dean Seehusen and Kaitlin Kehoe concluded that cannabis produced “small to moderate short-term pain relief” in patients with neuropathic pain. Similarly, a review of cannabis and pain management in the current issue of the Journal of the American Board of Family Medicine found low- and moderate-quality evidence that cannabis relieves neuropathic pain or rheumatoid arthritis, fibromyalgia, and other chronic noncancer-related pain. Adverse effects are common, with the most serious and prolonged being cannabinoid hyperemesis syndrome. A previous AFP article presented a suggested approach to distinguishing high-risk use and cannabis use disorder from potentially appropriate medical uses.

In New York, where recreational cannabis became legal in 2021, a New York Times Magazine story examined the problems associated with regulating sales of a substance that, similar to tobacco and alcohol, is highly addictive. Unlicensed shops dispensing cannabis vastly outnumber legal dispensaries because the former’s products can be priced more cheaply and thus cater to customers with cannabis use disorder:

Perhaps marijuana is not as bad as alcohol or cigarettes. But saying it is not as bad misses the point: Marijuana does hurt a substantial portion of its consumers, often quite badly. And there is no reason to think that businesses won’t sell marijuana to those it hurts, if they’re allowed to. What the alcohol and tobacco markets show us, rather, is that addiction and profit don’t mix well. … The goal is to find a balance between the harms of prohibition and those of commercialization.

Although many adults in the United State believe that cannabis use and secondhand smoke exposure is safer than that from tobacco, there is ample evidence of negative effects on short- and long-term outcomes. An FPIN Clinical Inquiry found that legalization of recreational cannabis is associated with an increase in cannabis-related emergency department visits. A recent systematic review and meta-analysis of 63 observational studies (n = 438,329) concluded that cannabis use in those younger than 24 years is associated with lower school grades; lower likelihood of high school graduation, university enrollment, and postsecondary degree attainment; and increased school dropout rates and absenteeism.

Finally, a cross-sectional analysis of data from the 2021-2022 National Survey on Drug Use and Health found that 16% of full-time employed adults used cannabis in the previous month, with 6.5% meeting criteria for cannabis use disorder. A dose-response relationship occurred between increasing frequency of cannabis use and cannabis use disorder severity and increased incidence of missed work for illness, injury, or nonmedical reasons.