I Want to Know More Icon

Why Teens Shouldn’t Use Marijuana

Listen to an audio file of this tool.


Children, adolescents, and young adults are particularly susceptible to the negative effects of marijuana due to their developing brains.1 Marijuana can impact a teen’s present life by increasing their risk for dropping out of high school, and it can affect their future because of the impact marijuana has on a developing brain that can be significant and long lasting.2,3

Preventing your teen from using marijuana, whether that means preventing them from ever using or delaying their start until at least the age of 21, greatly minimizes the negative and long-term impact of marijuana on the brain. To equip you, as a parent or someone in a parenting role, to have conversations with your teen about marijuana and the importance of not using during the teenage years, let’s explore reasons to be concerned about marijuana use, consequences of marijuana use, and specific strategies you can implement to encourage your child not to use marijuana.

Most Montana high school students (79%) do not use marijuana, and students who do use marijuana are 7 times more likely to also use other drugs.4

Why Be Concerned?

The potential impacts of marijuana use among teens are varied and can be severe. By summarizing research on marijuana addiction, the Centers for Disease Control and Prevention finds that 1 in 10 people who use marijuana will become addicted, but using marijuana before the age of 18 increases the likelihood of addiction to 1 in 6. Addiction is a serious illness that can lead to problems in all facets of life — school, work, home, and family.5

Marijuana use in teens is also associated with mental health issues, such as depression, anxiety, and even psychosis.5

Teens are often excited for the independence that comes with driving, but marijuana use impacts coordination and reaction time, which can have devastating effects on the road. Motor vehicle crashes and other unintentional injuries are the leading cause of death for teens and young adults. Marijuana use increases the risk of car crashes and other injuries.5,6

Marijuana use during adolescence can cause significant and long-lasting changes in the structure and function of the brain, especially with regular or heavy use. However, these negative impacts can be significantly reduced if marijuana use is avoided altogether or at least until the brain is fully developed in a person’s mid-20s or later.5

Parents and those in a parenting role may underestimate the likelihood that their child could be using marijuana or perceive their teen’s use is occasional and therefore not harmful. Approximately 1 in 5 Montana high school students use marijuana and, of those, nearly half (42%) report using marijuana more than 10 times a month.4 Particularly with recent legalization of adult-use marijuana in Montana, most teens will be exposed to marijuana. Teens are at risk, and parents have the potential to reduce this risk.

Consequences of Teen Marijuana Use

Marijuana use has both short-term and long-term effects on the brain and performance.

Short-Term Consequences

Marijuana use negatively impacts cognition, that is someone’s ability to think clearly and problem solve, as well as their memory and ability to learn new information and skills. While some people believe that marijuana use increases creativity and improves focus, the negative effects are more likely and far outweigh the potential for a very brief immediate benefit. And in fact, rather than improve focus, marijuana use in teens has been shown to contribute to difficulty paying attention. Together, these impacts on thinking, learning, and attention mean that teens who use marijuana are more likely than their peers who do not use marijuana to earn lower grades and to drop out of school.3

Marijuana use also impairs coordination and reaction time. Along with reduced decision making ability and concentration, these effects increase the likelihood for car crashes and other accidental injuries.3

Long-Term Consequences

Marijuana use during the teen years can damage the developing brain in ways that are long-lasting and may even be permanent. Research has linked adolescent marijuana use to problems with memory in adulthood, even among people who stopped using marijuana as adults. Other research has found a connection between adolescent marijuana use and lower IQ scores in adulthood, especially when marijuana use started at a young age and continued into adulthood.7

The percentage of Montana high school students who tried marijuana for the first time before age 13 has decreased over the last ten years. Still, 7.5% of Montana high school students in 2019 said they had tried marijuana for the first time at an age younger than 13.8

As described previously, teen marijuana use is associated with dropping out of high school.3 This can lead to long-term consequences as students are unlikely to return and therefore not graduate, achieving lower education overall. Marijuana use in teen years and earlier is also associated with both unemployment and fewer weeks of employment per year in adulthood.9

Some research studies find conflicting results, and rigorous research on the long-term consequences of marijuana use is ongoing. While it is impossible to know exactly how marijuana use will impact your teen’s developing brain, there is no evidence that teen marijuana use is beneficial. The safest route is to avoid marijuana use altogether or to delay use until the legal age of 21 or older, particularly given the increased risk of addiction when marijuana use starts during adolescence.

Using marijuana during the teen years increases the risk of addiction and other long-term consequences.3

The Key Role of Parents

As a parent or someone in a parenting role, you are the most important, number one, influence in your child’s life. You play an essential role in your child’s decision to not use marijuana, and there are a number of ways you can. When parents talk with their children about marijuana use and the negative impacts, model healthy and positive behavior, and stay involved in their children’s lives, they have a direct impact on whether their children decide to use marijuana.10

Youth need a trusted adult in their life. A positive bond with a parent or other adult is a protective factor against drug use and other risky behaviors.11

Youth who learn about the risks of drug use from their parents are less likely to use drugs than those who don’t.11

Strategies to Prevent Marijuana Use

Talk and Listen

  • Have frequent conversations with your teen about marijuana (as well as alcohol and other drugs), peer pressure, and decision making in risky situations. These conversations can begin as early as 8 years old. You don’t have to wait for your child to bring it up, nor do you have to wait for the right situation. Any moment is a teaching moment, and having conversations frequently without it needing to be an event helps your teen know that they can bring up difficult topics anytime. Ask a question like “Why do you think it is important not to use marijuana?”
  • Equip your teen with refusal strategies and practice these with your teen. Talk about different ways to say no and run through different “what if” scenarios. The more your teen practices with you, the more prepared they will be to use these skills in higher-risk situations. You might ask, “How would you respond if your friend insists on driving even though you know your friend had just smoked marijuana?”
  • Avoid sending mixed messages about marijuana. Know that you are always modeling for your child. If you use marijuana, think carefully about whether you do so in front of your child and, if you choose to, use only small amounts.
  • Your teen might express belief that marijuana is a medicine and can be helpful in treating physical pain or other ailments or reducing mental health symptoms. Be clear with your teen that unless under the care of a physician, marijuana should not be used medically and is illegal for people under the age of 21.
  • Keep talking even if your teen decides to try marijuana or violates an agreement or rule. Keep the lines of communication open.

Information on intentional communication can be found in the I Want to Know More section of the ParentingMontana.org website.

Establish Clear Rules

  • Develop rules with your teen regarding substances, including marijuana, alcohol, and other drugs. Cover a variety of different scenarios including marijuana use, if there is marijuana or alcohol at a friend’s house, driving after using marijuana or drinking alcohol, riding with someone who has been using marijuana or drinking, etc.
    • “I want us to be really clear about what the rules are given you are going to this party…”
    • “Tell me what you understand about our agreements regarding alcohol and marijuana as well as driving.”
    • “Let’s talk through why it is so important that you are where you say you are and what happens if you are not.”
  • Set clear consequences for violations of these rules. The consequences need to be clear, immediate, and bothersome.
  • Develop clear expectations regarding what behavior you are seeking. It is helpful for a teen to know what you do want to see, not just what you don’t want to see.
  • Catch your teen doing things right. Work hard to look for times when your teen is abiding by the rules. Praise your teen for this behavior.

Model Positive Behaviors

  • Include your teen in conversations about complex topics like current affairs, moral dilemmas, or discussions about addiction and crime.
  • Take responsibility for your actions and avoid blaming outcomes on others. This will help teach your child to take responsibility for their own actions as well.
  • Talk overtly about your values. One way to do this is to share with your child the values that drive your decision making.
  • Rather than only saying “no” to something, provide your teen with the rationale. This will help them understand your values and develop decision-making skills.
  • Model thoughtful decision making. Talk about your process of making decisions and walk your child through how you consider options as well as the consequences of each option. This will help your child slow down when making decisions and think through consequences.
  • Be careful about making statements such as, “It’s rough out there; I see why people smoke weed” or “Thank goodness that day is over — it’s wine time!” in front of your child. Statements like these can teach children that marijuana or alcohol are appropriate ways to manage stress.
  • If you use marijuana, consider whether you want to do so in front of your child. If you choose to, limit your use to small amounts.
  • Never drive after using marijuana or drinking alcohol and always use a seat belt.


  • Monitor your child’s activities so you know where they are at all times.
    • “Thank you for telling me where you will be this evening. I will follow up by calling you as well as calling the house where you will be.”
    • “I know we agreed to an 11pm curfew, and you were back later than that. Let’s talk through what happened, what you could have done differently, and the consequences of your actions.”
  • It is normal for a teen to lie about their whereabouts, especially if they think they can get away with it. Check they are actually where they say they are. For example, if your child says they are at a friend’s house, call the parents to verify.
  • If you are hosting a party at your home, monitor your teen and your teen’s friends on a regular basis. You can do this under the guise of offering them food.
  • Teens whose friends use marijuana are more likely to use themselves.12 Learn about your child’s friends and encourage their friendships with peers who do not use marijuana or other substances.
  • If your child will be at a party at someone else’s house, talk with the host about whether alcohol or marijuana will be available and how the kids will be supervised. Be open about doing this so your child knows that you take this seriously.
  • If you have marijuana or alcohol in your home, store it securely so it is not accessible to your teen and monitor the supply to ensure none goes missing.

Clarify Misperceptions

  • Teens are influenced by what they perceive others are doing and their perception of whether their peers are using marijuana predicts their own marijuana use. Unfortunately, they also frequently overestimate how often other teens use marijuana and other substances.12,13 Explain to your teen that most of their peers do not use marijuana.
    • “It sounds like you think most teens use marijuana. In fact, most Montana teens don’t use marijuana. Let’s talk more about that.”
    • “I’m worried we don’t see eye to eye on this. Let’s talk through it.”
  • If your teen disagrees with you about the prevalence of marijuana use, ask them more about their views and why they believe as they do. Remember that their friends’ use of marijuana can be influential, so if your teen reports that all their friends use marijuana, you might explore ways to expand their circle of friends.
  • Avoid getting into arguments and instead gather information together. Do some research on prevalence rates in your city, county, or state together.
  • Avoid adding to the misperceptions by making statements like, “Being a teen is about trying out adult choices” or “Making bad choices is what teens do.”


The teen brain goes through a significant development and maturation process that continues into the mid-20s. During this vulnerable time for the developing brain, marijuana use can significantly impact the structure and function of the developing brain, and some of the impacts can be long lasting.

By avoiding marijuana, youth can greatly reduce these negative impacts. As a parent or one in a parenting role, you are key to helping your child prevent harm associated with marijuana. By implementing strategies such as talking and listening, establishing rules, modeling positive behavior, monitoring, and clarifying misperceptions, you can make a difference in your child’s life.

Connect with other Montana parents about marijuana use and underage drinking at LetsFaceItMt.com.

Download and print the at-a-glance resource highlighting key information for why teens shouldn’t use marijuana.



[1] Cohen, K., & Weinstein, A. (2018). The effects of cannabinoids on executive functions: Evidence from cannabis and synthetic cannabinoids: A systematic review. Brain Sciences, 8, 40-58.
[2] Silins, E., Horwood, L. J., Patton, G. C., Fergusson, D. M., Olsson, C. A., Hutchinson, D. M., Spry, E., Toumbourou, J. W., Degenhardt, L., Swift, W., Coffey, C., Tait, R. J., Letcher, P., Copeland, J., & Mattick, R. P. (2014). Young adult sequelae of adolescent cannabis use: An integrative analysis. The Lancet Psychiatry, 1, 286–293.
[3] Centers for Disease Control and Prevention. (2017). What you need to know about marijuana use and teens. Retrieved from https://www.cdc.gov/marijuana/factsheets/pdf/MarijuanaFactSheets-Teens
[4] Montana Office of Public Instruction (n.d.). 2019 Montana Youth Risk Behavior Survey: High school results. Helena, MT: Author. Retrieved from https://opi.mt.gov/Portals/182/Page%20Files/YRBS/2019YRBS/2019_MT_YRBS_FullReport.pdf
[5] Centers for Disease Control and Prevention. (2018). Marijuana: How can it affect your health? Retrieved from https://www.cdc.gov/marijuana/health-effects/
[6] Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. (2018). 10 leading causes of death by age group, United States – 2018. Retrieved from https://www.cdc.gov/injury/wisqars/pdf/leading_causes_of_death_by_age_group_2018-508.pdf
[7] National Institute on Drug Abuse. (2020). Marijuana research report: What are marijuana’s long-term effects on the brain? Retrieved from https://www.drugabuse.gov/publications/research-reports/marijuana/what-are-marijuanas-long-term-effects-brain
[8] Centers for Disease Control and Prevention. (n.d.). 1991-2019 high school Youth Risk Behavior Survey data. Retrieved from https://yrbs-explorer.services.cdc.gov/#/graphs?questionCode=H46&topicCode=C03&location=MT&year=2019
[9]Beverly, H. K., Castro, Y., & Opara, I. (2019). Age of first marijuana use and its impact on education attainment and employment status. Journal of Drug Issues, 49, 228–237.
[10] Ryan, J., Roman, N., & Okwany, A. (2015). The effects of parental monitoring and communication on adolescent substance use and risky sexual activity: A systematic review. The Open Family Studies Journal, 7, 12-27.
[11] The U.S. Department of Education, The Drug Enforcement Administration. (2017). Growing up drug free: A parent’s guide to prevention. https://www.dea.gov/sites/default/files/2018-06/growing-up-drug-free-2017.pdf
[12] Roditis, M. L., Delucchi, K., Chang, A., & Halpern-Felsher, B. (2016). Perceptions of social norms and exposure to pro-marijuana messages are associated with adolescent marijuana use. Preventive Medicine, 93, 171-176.
[13] Pedersen, E. R., Miles, J. N. V., Ewing, B. A., Shih, R. A., Tucker, J. S., & D’Amico, E. J. (2013). A longitudinal examination of alcohol, marijuana, and cigarette perceived norms among middle school adolescents. Drug and Alcohol Dependence, 133, 647-653.
Recommended Citation: Center for Health and Safety Culture. (2021). Why Teens Shouldn’t Use Marijuana. Retrieved from https://parentingmontana.org.
Print Friendly, PDF & Email