Marijuana and teens: What parents should know

As a growing number of states legalize marijuana and public perceptions shift, more teens may feel that marijuana isn't dangerous – putting them at higher risk for marijuana use.

"Teens may think because it is legal, it is safe," says David L. Atkinson, M.D., Medical Director of the Teen Recovery Program at Children's Health℠. "Most of these teens believe in the idea that it is a medicine. They think doctors wouldn't prescribe a medicine that is harmful, but in fact medicines are harmful when used without a prescription or without doctor supervision."

Learn about the risks of marijuana use in teens and ways to talk to your child about the drug.

What are the effects of marijuana on the teenage brain?

Marijuana has toxic effects on the developing brain. A 2018 study showed marijuana is more damaging than alcohol to adolescent brains, leading to problems with memory and inhibiting impulses that persist after marijuana is stopped.

"Marijuana is addictive," says Dr. Atkinson. "Like any drug, how addictive it is depends on how much people use, how they get it into the brain and what age they start using."

Starting marijuana use at a young age means the drug is more addictive due to how teenage brains work. Teenage brains seek out strong sensations and are often willing to take more risks than adult brains, a combination that could lead to a higher use of drugs. Heavy marijuana use can also make teens more likely to become addicted to other substances, particularly opioids, later in life.

Marijuana use and mental health in youth

Heavy use of marijuana at a young age – especially before the age 16 – has been strongly linked to an increased risk of developing schizophrenia later in life. THC, the main psychoactive ingredient in marijuana, can trigger psychotic symptoms, including hearing voices and seeing things that aren't there.

Research shows that the connection between teen marijuana use and schizophrenia cannot be explained by genetics alone. The risk appears to increase with higher-potency products and more frequent use. Adolescence is a critical time for brain development, and marijuana can disrupt the brain’s developing communication pathways in ways that may have lasting effects.

Marijuana use in teens has also been associated with a higher risk of suicide attempts. Even when researchers account for other factors — such as depression, trauma or other mental health conditions — teens who use marijuana may be two to four times more likely to attempt suicide.

Another common effect of marijuana is reduced motivation. For teens, this can be especially significant. Adolescence is a time filled with important academic, social and extracurricular opportunities. When motivation drops, teens may miss out on experiences that help shape future education, careers and relationships.

Marijuana’s effects on memory

Marijuana can also affect memory – particularly working memory, which is the ability to hold and process multiple pieces of information at once. This skill is essential for learning, problem-solving and academic success.

Some studies suggest that heavy marijuana use during adolescence may lead to long-term or even permanent changes in memory and thinking skills. One large study found that people who used marijuana regularly as teens had an average IQ decline of 6 to 8 points – and stopping use in adulthood did not fully reverse those effects.

Because the teenage brain is still developing, it may be more vulnerable to these long-term impacts than the adult brain.

Vaping and marijuana

With the growing popularity of vaping, marijuana can become even more accessible to teens. A 2018 study found that nearly 1 in every 11 middle and high school students have smoked marijuana using e-cigarettes.

Dr. Atkinson warns that vaping marijuana has unique risks.

"The use of e-cigarettes to vape has enabled students to get away with using marijuana much more often and in more locations than they typically would," says Dr. Atkinson. "There's not much of a smell produced, and kids can assure anxious parents that it is just flavoring or just nicotine, not marijuana."

Dr. Atkinson warns that some vaping cartridges can be up to 90 percent pure marijuana and even CBD oil cartridges may contain THC.

"E-cigarettes also allow kids to 'microdose' marijuana all day long," says Dr. Atkinson. "They give themselves a small amount up to 30 times per day."

Teens have an extensive and rapidly evolving vocabulary for the substances they use. Disposable e-cigarettes are known as “dispos” and contain what is thought to be 2 grams of THC. “Carts” are reusable cartridges of cannabis concentrates that are used in vapes.

Vaping throughout the day, even in tiny doses, leads to heavy use among teens – putting them at risk for long-term health problems.

How parents can talk to teens about marijuana

The best way to prevent these effects on your child's long-term health is to talk to them about marijuana before they are ever exposed to the drug – as young as 10 or 12 years old. Dr. Atkinson says you should make your expectations about no drug use clear and speak openly and honestly about marijuana.

"It's important to build trust with your child," says Dr. Atkinson. "Don't exaggerate the facts. For instance, while it is addictive, not everyone gets addicted, but everyone is at risk for addiction."

Dr. Atkinson says it is okay for parents not to know all the answers about drugs. If kids have questions, you can look them up together on reputable websites. Parents should also answer questions about their own past use honestly and include why they never used or stopped using, whether it was to get a job, do well in school or maintain stronger relationships.

Signs of marijuana use in teens

If you are concerned your child is using marijuana, you can look for signs of substance use such as:

• Reddened eyes

• Giddy or euphoric behavior

• Laughing inappropriately

• Drug paraphernalia like bongs, rolling papers or vape pens

• Chat messages about drug sales (70% of teens purchase drugs with a social media transaction using an electronic payment service)

• Candies that look like knockoffs of major brands, particularly gummies

• Any suspicious product can be investigated with an AI-enhanced image search of a photo taken of the item

• Friends using marijuana

• Common mentions of marijuana in the teen's music or conversations

While these signs may not mean that your child is using marijuana, they can be a good starting point for a constructive, positive and open conversation about the potential harms of marijuana.

Learn more

If you are concerned about your child's drug or alcohol use, the Teen Recovery Program at Children's Health can help them improve mental health and overcome addiction.