Health Risks of Marijuana 

May 16, 2022

Marijuana use is becoming increasingly common, for both medical and recreational purposes. As of April 2022, 37 US states had legalized cannabis for medical use, while 18 of those states also had legalized it for recreational use. Additional states allow CBD, which has some established health benefits and does not have any psychoactive effects. Only Idaho and Nebraska have not legalized marijuana to any extent (1). A flurry of research in recent years has suggested several health benefits for the substance (2,3), but there are also health risks associated with marijuana that should be taken into account (3-6). 

Medical uses of marijuana include reducing discomfort associated with cancer and/or chemotherapy, stimulating appetite, treating epilepsy and muscle spasms, and treating several forms of pain. A literature review in 2015 found strong evidence in support of cannabinoids as a pharmacotherapy for chronic pain, neuropathic pain, and multiple sclerosis-associated muscle spasms. There is also some data suggesting that marijuana may be effective for glaucoma, and the FDA has approved synthetic cannabinoid drugs for chemotherapy-related nausea and HIV/AIDS-related appetite loss (2,3). 

Compounds in marijuana bind to natural cannabinoid receptors that are concentrated in the central nervous system (2). Effects can include analgesia, increased appetite, sleep promotion, and euphoria, but also impaired memory, cognition, and locomotor function (2-6). Despite the health benefits touted by supporters of marijuana legalization, experts caution that there are known risks as well, in a way that is perhaps similar to other legal but controlled psychoactive substances like alcohol and tobacco. 

The major health risks of marijuana use in the short term are impaired reflexes and motor skills, increased heart rate and blood pressure, lung irritation, and psychosis and paranoia (2-4). There have been more and more incidences of people driving under the influence of marijuana, which is associated with a higher risk of accidents (2-5). Individuals with cardiovascular disease, asthma, and mental health disorders should exercise additional caution with marijuana due to those effects. 

Long-term use may lead to addiction and lung diseases in the case of smoking marijuana, and may worsen mental health symptoms (2-5). It is a common misconception that marijuana is not addictive; in fact, studies estimate the risk of addiction to be 10-30%. Those who start using marijuana before adulthood and/or use it more frequently are at higher risk (4). Just like with cigarettes, many of the chemicals produced by burning marijuana are irritants, toxic, and/or carcinogens. Other airborne forms of marijuana, such as vapes or pipes, also are harmful for your lungs (4). 

Another major concern of regular marijuana use in teens specifically is that it may impair brain development, especially in the areas of attention, memory, and learning. Brain development continues into one’s twenties, and the brain is generally more vulnerable to disruption while development is ongoing (2,4,5,6). 


  1. K. A. Smith. “House Passes Bill To Legalize Marijuana. What’s Next?” Forbes, April 2022. 
  1. K. P. Hill. Medical Marijuana for Treatment of Chronic Pain and Other Medical and Psychiatric Problems: A Clinical Review. JAMA, 2015;313(24):2474–2483. doi:10.1001/jama.2015.6199 
  1. “Marijuana.” Mayo Clinic, November 2020. 
  1. “Health Effects of Marijuana.” Centers for Disease Control and Prevention, June 2021. 
  1. D. Hasin. US Epidemiology of Cannabis Use and Associated Problems. Neuropsychopharmacology, 2018;43:195–212. doi:10.1038/npp.2017.198 
  1. A. Levine, K. Clemenza, M. Rynn, J. Lieberman. Evidence for the Risks and Consequences of Adolescent Cannabis Exposure. Journal of the American Academy of Child & Adolescent Psychiatry, 2017;56(3):214-225. doi: 10.1016/j.jaac.2016.12.014