Dangers of Using Marijuana in Adolescence

Nia Coppack
Author: Nia Coppack Medical Reviewer: Morgan Blair Last updated:

As of 2011, marijuana is the most commonly used illicit drug by adolescents in the US and it has been for almost 40 years. It is a drug that can have serious negative impacts on academic and social functioning for adolescents, not just during the teenage years, but extending into adult life. [2]

What are the dangers of using marijuana during adolescence?

As of 2019, marijuana use has been growing steadily for the past few decades. Currently, adolescents are more likely to use marijuana than tobacco. 37% of high school students in the US were found to have used marijuana at least once in their lifetime and 22% had used it in the past 30 days. Similarly, in the UK, it is estimated that between 20-30% of 17-year-olds have used marijuana within the past year. Due to the variety of adverse effects on cognitive development and links to other negative consequences, these statistics illustrate a current substantial social problem among adolescents. [1]

The increase in marijuana use by adolescents may be due to a myriad of factors, but the most prevalent, is the decrease in overall “perceived risk” of marijuana usage. In 1992, 80% of 17–18-year-olds in the US perceived marijuana use as a “great risk”. 10 years later, only 45% of the same age group considered it a “great risk”. This dramatic decrease within a short period of time shows the change of cultural attitude and could explain the subsequent increase in use. [2]

Marijuana use can have an adverse effect on the health and wellbeing of a person of any age. However, adolescents are particularly at risk. The human brain is still actively developing during the teenage years and stopping only around 25 years of age. These developmental years help to create efficient neural pathways, allowing the individual to reach their optimal brain function. Using cannabis during this period can have a significant effect, causing substantial changes in the brain matter and creating long lasting negative effects on behaviour and cognitive function. [1]

Short term use of marijuana can lead to [3]:

  • Issues with memory or concentration
  • Increased aggression
  • Risky sexual behaviours
  • Increased risk of other mental illnesses such as psychosis or schizophrenia
  • Worsening underlying mental health illness such as anxiety or depression

Long term use of marijuana increases the risks above but can also lead to significantly more problems [2]:

  • Cannabis Use Disorder (addiction)
  • Breathing difficulties such as coughing, wheezing and increased risk of lung cancer
  • Decreased motivation or interest which can lead to a decline in academic or occupational performance
  • Lower IQ
  • Increased risk of other mental illnesses – People who use marijuana are more likely to experience temporary psychosis, which is an illness where you may experience hallucinations, delusions or paranoia. Temporary psychosis can lead people who use marijuana to develop The relationship between marijuana usage and schizophrenia strengths in people who started using marijuana earlier and those with higher frequency.

There are a few common misconceptions about marijuana, leading many teenagers to believe that marijuana is safer than alcohol and other drugs. Increasing the conversation around marijuana and educating adolescents about the dangers of usage is a good way to decrease the number of teenagers using recreationally.

Below are three common myths and the reality [1]:

  • Many people think that marijuana is a non-addictive drug – this is incorrect. Approximately 3 out of 10 people who use marijuana suffer from cannabis use disorder. The treatment for which is similar to other addictions and may include rehab, therapy, and healthy support systems. The risk of developing this disorder increases in people who started using marijuana earlier and those with higher frequency.
  • Some believe that marijuana usage does not have any long-term effects. However, there are several long-term effects to marijuana usage.
  • It is harmless because it is “natural” – Many plants and naturally occurring substances can be harmful or in fact deadly. Additionally, marijuana has been changed substantially due to medical and market pressures. Recreational marijuana has seen to have changed in composition during this period with increases in tetrahydrocannabinol (THC), the mind-altering chemical that provides the “high”. Whereas the ingredient thought to provide the most medical benefit, cannabidiol (CBD) has not increased and remains at 1%.
  1. CDC Center for Disease Control and Prevention, 2021. Teens. https://www.cdc.gov/marijuana/health-effects/teens.html
  2. Jacobus, J. and Tapert, S.F. (2014) Effects of Cannabis on the adolescent brain. National Center for Biotechnology information 20(13): 2186–2193. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3930618/
  3. American Academy of Chile and Adolescent Psychiatry, 2019. Marijuana and Teens. https://www.aacap.org/AACAP/Families_and_Youth/Facts_for_Families/FFF-Guide/Marijuana-and-Teens-106.aspx
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Nia Coppack
Author Nia Coppack Writer

Nia Coppack is a medical writer and mentor with a background in Biochemical Engineering and Ecology and Evolutionary Biology from Newcastle University.

Published: Aug 23rd 2023, Last edited: Jan 31st 2024

Morgan Blair
Medical Reviewer Morgan Blair MA, LPCC

Morgan Blair is a licensed therapist, writer and medical reviewer, holding a master’s degree in clinical mental health counseling from Northwestern University.

Content reviewed by a medical professional. Last reviewed: Aug 22nd 2023