woman smoking a marijuana cigarette

Everything You and Your Teenager Should Know About Cannabis

Marijuana and teenagers have been in a relationship for years. Now, as more states make recreational use legal for adults, and the strength of products increases, the risks have changed. Or have they?

Sarah Ann Anderson, MD

Sarah Ann Anderson

A 2022 study by the Mailman School of Public Health found cannabis use is increasing in the United States among people of all ages, especially in cigarette smokers and in states where cannabis has been legalized for nonmedical use. But too few studies offer definitive answers about the impact of cannabis use on teen health.

We spoke with pediatrician Sarah Anderson, MD, PhD, an expert in adolescent medicine, to find out what is known and how parents can best protect the health of young people curious about using marijuana.

Accept that teens will encounter cannabis

First, adults must confront their own biases and issues. “Kids are going to be exposed to cannabis. They're going to have friends who sample it,” says Anderson. “You need to be comfortable talking with them, because by not talking to teenagers, by not guiding them, you're potentially doing them more harm.”

Second, adults must accept that people of all ages take risks and that taking risks is a part of learning. “We learn over time what is too dangerous and what’s not,” says Anderson. “One role of parents, caregivers, clinicians, and the support system around teenagers is to guide them on how to take safer risks to guide their development.”

How to talk to teenagers about cannabis

The key is communication: talking, asking questions, listening, and answering questions. “If you don’t know the answer to something, be honest, research it together by finding a reliable primary source, like a doctor,” Anderson says. “You want them to know what to look for when their friends are using and to be aware of unsafe scenarios. Secrecy leads to trouble.”

Ideally you want teenagers in your life to be comfortable disclosing to you, as parent, guardian, or supporting adult, that they are trying or using cannabis and if they’ve had a bad reaction or experience.

Teens may use marijuana for many reasons: social status and fitting in; to help with anxiety, depression, or stress; or genuine curiosity about effects.

“Whatever their experience, it’s good to find out more,” Anderson says. “Is their use a concern? Are they doing it to escape or have fun? Are they dealing with anxiety or depression? The more you know the more you can help guide and support them.”

It is also important to address the legal concerns, she adds: “Know your state’s laws. Teenagers who are members of marginalized communities will be targeted by legal authorities more than their peers. It is vital to have the discussion of legal implication of possession and use.”

Why cannabis is bad for teens

The brain continues to develop until around age 25, and development during the teenage years is dramatic. Drugs and alcohol can interfere with brain development; impair thinking, memory, and learning; create paranoia; and affect executive functioning (problem-solving).

A concern is that THC—the component in marijuana that creates the “high” feeling—is getting stronger and stronger.

“It is still unknown how long marijuana’s effects last and if brain alterations may be permanent,” Anderson says. “That is part of the risk at this time. Much is still unknown because there have not been enough studies.” The NIH is funding a major research project—The Adolescent Brain Cognitive Development Study of nearly 12,000 youth—to find out more.

Parents often ask Anderson if marijuana use lowers the IQ of teenagers. “There has not been enough research and what exists is inconclusive,” Anderson says. “We do have animal and human studies that point to impaired cognitive functioning as a result of use, but it’s difficult to directly link marijuana to IQ without taking into account other substance use. Some studies have linked regular, persistent marijuana use starting in adolescence to declines in IQ and substance use disorder later in life, but other studies do not.”

Cannabis use and schizophrenia

Anderson notes this topic gets a lot of traction in the press, but the data are not clear and cannabis use cannot be definitively connected to the onset of schizophrenia.

Schizophrenia onset is multifactorial. If a person is already genetically predisposed to schizophrenia, any change in neurochemistry—caused by stress, THC use, and other things—might lead to onset. Schizophrenia is closely linked to genetics. Teenagers who have a parent or sibling affected by schizophrenia and other psychoses have a one in 10 chance of developing the same condition even if they do not use marijuana.

Marijuana overdose and toxicity

An overdose happens when someone uses enough of a drug to instigate life-threatening symptoms or death.

“There is no such thing as marijuana overdose,” Anderson says. Though no teenagers have died from marijuana use alone, other substances can be fatal when mixed with marijuana. Also, marijuana toxicity can lead to negative consequences and health outcomes.

Cannabis hyperemesis syndrome (CHS) is one type of marijuana toxicity that Anderson has encountered in several patients admitted to the hospital. CHS leads to nonstop vomiting in regular users, and a person could die from the dehydration caused by CHS. Because many teens combine marijuana with tobacco, a trend in New York City, Philadelphia, and other areas, they may also start having nicotine withdrawal if they experience CHS.

What teens ask about cannabis

Anderson asks every patient about cannabis use, and her patients know they can answer truthfully because of New York state confidentiality laws regarding substance use, which Anderson affirms at each visit. Unless she is concerned about the patient’s personal safety, answers are confidential.

These conversations help teens and young adults build confidence and empower them to use their voices, Anderson says, especially when it comes to their health and well-being.

Common questions from patients:

How will I feel when I use marijuana?

“People may feel any or all of the following: euphoria, relaxation, sensory perception changes, appetite changes, paranoia, anxiety, impaired coordination, and judgment, but there is no way to know in advance,” says Anderson.

“Marketing is confusing and misleading,” she adds, using as examples the promotion of indica as the way to chill out and sativa as the way to be energized.

What is the difference between THC content and CBD content?

Marijuana comes in many forms with most containing THC and CBD in varying amounts. THC is commonly associated with more euphoric effects, whereas CBD is associated with more anxiety-reducing effects.

Decades ago marijuana had more CBD content than THC. With genetic modification, THC content increased 212% between 1995 and 2015, flipping the potency and effects. And THC content continues to rise. For all cannabis users, the safest choice, Anderson says, is the lowest dose.

How can I assess the quality of cannabis products?

Cannabis products that are grown, manufactured, and sold legally have been tested by third party sources for quality control and to determine strength. Products that are not tested may contain other substances.

In New York City,  only four dispensaries are currently authorized to sell cannabis products. “Cost and access are different depending on socioeconomic status and the community,” says Anderson.

“Even with the legalization of marijuana, teens are underage and will not be able to access these dispensaries, where cost can be prohibitive. Teens are likely to obtain marijuana from outside sources, particularly in communities that are marginalized and overrepresented in the carceral system." 


Sarah Ann Rachel Anderson, MD, PhD, is assistant clinical professor of pediatrics at Columbia University Vagelos College of Physicians and Surgeons and director of medical services and quality improvement for the Primary Care Health Service at Barnard College.