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Risks of Adolescent Marijuana Use

Health Risks Vary by Type of Use

Marijuana can be used in different ways, including smoking, vaping, eating as an “edible,” or dabbing, which means smoking or inhaling marijuana in the form of hash oil or wax. Over the past decades, the typical percentage of tetrahydrocannabinol (THC), the most active ingredient in marijuana, has increased in marijuana and marijuana products, making them more potent. There are different health risks associated with different methods of using marijuana. For example:

  • Smoking marijuana can lead to breathing problems.
  • Eating marijuana is linked with a greater risk of poisoning. 

High amounts of THC can increase the risk for negative effects. The consequences of being exposed to high levels of THC, including addiction, are still not well-understood. 

Using marijuana and alcohol together can be especially unpredictable and harmful. Driving under the influence of marijuana can also lead to injury or death for users and those sharing the road with them.

Health Effects Can Be Long-Term

While policy, public opinion, and the perception of harm are changing, researchers are still studying the long-term health effects of marijuana. Most people agree that marijuana use hurts adolescents more than adults. However, anyone who uses marijuana may suffer from negative health effects, such as testicular cancer, heart attacks, respiratory disease, a weakened immune system, pregnancy complications, and low birthweight. In addition to physical health effects, marijuana use also is linked with cognitive problems; low academic achievement and other educational outcomes; impaired social functioning; and mental health disorders, including depression and anxiety. 

Brain Development 

Research on marijuana use and its long-term effects on the human brain have shown mixed results. Still, a fair amount of research shows marijuana can have negative effects for adolescents. Such effects can include:

  • Changes to the brain’s structure (including size and how areas are connected)
  • Lower quality of brain connections
  • Less blood flow to parts of the brain1

These changes may hurt brain functioning in adolescents. Marijuana use has been linked to lower IQ scores as well as poorer memory and attention. There is added concern because adolescence is an important time in development when young people’s brains are building the connections to improve executive functioning (e.g., self-control, creative thinking, and decision-making skills). 

Scientists still have many questions about how marijuana affects the brain long-term. Factors that can shape marijuana’s effects on the brain include when someone starts using marijuana, how often they use it, and whether they use other substances at the same time. To provide a clearer picture, several studies are underway. For example, the National Institutes of Health Adolescent Brain Cognitive Development (ABCD) study is gathering a large sample of data across several sites and over many years. 

While scientists work to have a better understanding of the specifics, the fact remains – the brains of young people grow and are formed up through their mid-20s. It is important to protect those brains by preventing exposure to substances that could harm them.   


Marijuana, like some other brain-altering substances, can be addictive. Nearly one in 10 marijuana users will become addicted. Signs that someone might be addicted include being unable to stop using marijuana, using it even though they know it is causing problems, and using marijuana instead of joining important activities with friends and family. People who frequently use marijuana often report withdrawal symptoms. These symptoms include being irritable or restless, having a small appetite, experiencing cravings, and problems with mood and sleep. These symptoms can last up to two weeks after the last use. In 2015, about four million people in the United States met the standards for being diagnosed with a marijuana use disorder.2

Starting to use marijuana at a younger age can lead to a greater risk of developing a substance use disorder later in life. Adolescents who begin using marijuana before age 18 are four to seven times more likely than adults to develop a marijuana use disorder.3

Legal Status of Marijuana

Marijuana is illegal under federal law. It is also illegal to drive under the influence of alcohol or drugs, including marijuana

State laws vary and are subject to change, but as of August 2017, people under the age of 21 cannot buy recreational marijuana, and people over 21 cannot give marijuana to people under 21. The most recent research suggests that, to date, states with medical marijuana laws have not seen an increase in adolescent use.4-7


1 Lisdahl, K. M., Wright, N. E., Medina-Kirchner, C., Maple, K. E., & Shollenbarger, S. (2014). Considering cannabis: the effects of regular cannabis use on neurocognition in adolescents and young adults. Current Addiction Reports, 1(2), 144-156.
2 National Institute on Drug Abuse. (2018). Marijuana: Is marijuana addictive? Retrieved from https://www.drugabuse.gov/publications/research-reports/marijuana/marijuana-addictive.
3 Winters, K. C., & Lee, C. Y. S. (2008). Likelihood of developing an alcohol and cannabis use disorder during youth: association with recent use and age. Drug & Alcohol Dependence, 92(1), 239-247.
4 Lynne-Landsman, S. D., Livingston, M. D., & Wagenaar, A. C. (2013). Effects of state medical marijuana laws on adolescent marijuana use. American Journal of Public Health, 103(8), 1500-1506.
5 Cerdá, M., Sarvet, A. L., Wall, M., Feng, T., Keyes, K. M., Galea, S., & Hasin, D. S. (2018). Medical marijuana laws and adolescent use of marijuana and other substances: Alcohol, cigarettes, prescription drugs, and other illicit drugs. Drug & Alcohol Dependence, 183, 62-68.
6 Hasin, D. S., Wall, M., Keyes, K. M., Cerdá, M., Schulenberg, J., O'Malley, P. M., ... & Feng, T. (2015). Medical marijuana laws and adolescent marijuana use in the USA from 1991 to 2014: results from annual, repeated cross-sectional surveys. The Lancet Psychiatry, 2(7), 601-608.
7 Carliner, H., Brown, Q. L., Sarvet, A. L., & Hasin, D. S. (2017). Cannabis use, attitudes, and legal status in the US: A review. Preventive medicine, 104, 13-23.


Content created by Office of Adolescent Health
Content last reviewed on April 8, 2019