Child mental health

Signs Your Teen May Be Using Cannabis

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No single sign proves cannabis use. A cluster is what matters: a persistent skunky smell, bloodshot eyes, new eye drops or body spray, shifts in sleep or appetite, slipping grades, or a changing friend group. Because these overlap with ordinary adolescent change, a pediatrician's confidential, validated screen is more reliable than any one clue.

Last updated: July 2026History

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What to actually look for

There is no checklist that confirms cannabis use, but parents most often notice a pattern rather than a single clue. Physical signs can include red or bloodshot eyes, a lingering skunky or sweet-herbal smell on clothes and in a room, frequent use of eye drops, mints, gum, or heavy cologne to mask odor, and changes in appetite (often increased) or sleep. Behavioral shifts can include a new or secretive friend group, declining grades or lost interest in activities that used to matter, more time spent alone or away, and money or valuables going missing. The hard part is that nearly all of these also describe a perfectly typical teenager who is tired, stressed, or simply growing up.

Why a cluster matters more than any one clue

Adolescence is, on its own, a season of big mood swings, new privacy, and shifting friendships. That is why clinicians look for a change from your teen's baseline and for several signs appearing together over weeks, rather than reading any one moment as evidence. It also helps to keep perspective: national survey data show that adolescent use of most substances has stayed at historically low levels in recent years 1. Most teens are not using, and noticing a few of these signs is a reason to ask gentle questions, not to assume the worst.

How clinicians screen for this

Pediatricians don't rely on guesswork. They use brief, validated screening tools designed for adolescents. The CRAFFT was developed and validated specifically as a short, developmentally appropriate screen for adolescent alcohol and other drug problems 2, and a score of 2 or higher is the established cut point that flags a likely substance-related problem and warrants a deeper conversation 3. Other validated screeners, such as the S2BI and BSTAD, use a single past-year frequency question to sort teens into risk levels with high accuracy 4. The American Academy of Pediatrics recommends that pediatricians routinely screen adolescents and offer brief intervention or referral as part of ordinary preventive care 5.

How can a pediatrician help if you suspect cannabis use?

A pediatrician brings tools and training that a worried parent at home does not have. They can administer a validated screen like the CRAFFT, S2BI, or BSTAD that distinguishes ordinary experimentation from a developing problem far better than a smell or a mood 24. They can rule out medical or mental-health explanations — sleep problems, depression, anxiety — that look a lot like substance use signs. When use is present, they can deliver evidence-based brief intervention and, if needed, connect your teen to treatment tailored to adolescents, which differs meaningfully from adult care 56. Many practices also offer a confidential one-on-one visit, which often surfaces an honest answer that a tense family conversation cannot.

What to do with what you notice

If you are seeing a pattern, write down what you have observed and when. Lead with care rather than accusation when you talk — curiosity keeps the door open. Then bring your observations to your teen's pediatrician, who can screen confidentially and guide next steps. Adolescence is the key developmental window for substance use problems to begin, which is exactly why early, calm attention matters 6.

Common questions

No. Each can have many ordinary explanations — allergies, lack of sleep, a friend who uses, or a new body spray. They are reasons to stay attentive and ask, not proof. A clinician's validated screen is far more reliable than any single physical sign.

Many families wrestle with this. Searching can damage trust and rarely settles the question on its own. A confidential pediatric screening visit is usually more productive and preserves the relationship you'll need for any real conversation.

It depends on the pattern. Clinicians use brief screens to tell low-risk experimentation from a developing problem, because adolescence is the main window when substance use disorders begin. That's the value of a professional assessment rather than guessing at home.

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Talk to a clinician

A pediatric clinician

Gale can help you find one in your state and request a visit.

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When to seek care sooner

  • —Signs of intoxication paired with confusion, severe vomiting, or trouble staying awake
  • —Talk of self-harm, hopelessness, or wanting to disappear
  • —A sudden, steep drop in functioning at school or withdrawal from everyone
  • —Use of cannabis combined with driving
  • —Suspected use of substances beyond cannabis, especially anything that could be laced

If your teen seems to be in immediate danger or is talking about suicide, call or text 988 (Suicide & Crisis Lifeline) or call 911. You can also text HOME to the Crisis Text Line at 741741.

This article is educational and not a diagnosis; please consult your teen's clinician about your specific situation.

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References

  1. 1.National Institute on Drug Abuse (NIDA), NIH; conducted by University of Michigan (Monitoring the Future) (2024). Reported use of most drugs among adolescents remained low in 2024 (Monitoring the Future survey). National Institute on Drug Abuse (NIH). link ✓National Monitoring the Future data show adolescent use of most substances has held at historically low levels.
  2. 2.Knight JR, Shrier LA, Bravender TD, Farrell M, Vander Bilt J, Shaffer HJ (1999). A new brief screen for adolescent substance abuse. Archives of Pediatrics & Adolescent Medicine. doi:10.1001/archpedi.153.6.591 ✓The CRAFFT was developed and validated as a brief, developmentally appropriate screen for adolescent alcohol and other drug problems.
  3. 3.Knight JR, Sherritt L, Shrier LA, Harris SK, Chang G (2002). Validity of the CRAFFT substance abuse screening test among adolescent clinic patients. Archives of Pediatrics & Adolescent Medicine. doi:10.1001/archpedi.156.6.607 ✓A CRAFFT score of 2 or higher is the optimal cut point for identifying substance-related problems in adolescents.
  4. 4.National Institute on Drug Abuse (NIDA) (2024). Screening Tools for Adolescent Substance Use (NIDAMED). National Institute on Drug Abuse (NIH). link ✓NIDA recommends validated electronic screeners (S2BI and BSTAD) that triage adolescents by past-year use frequency.
  5. 5.Levy SJL, Williams JF, AAP Committee on Substance Use and Prevention (2016). Substance Use Screening, Brief Intervention, and Referral to Treatment. Pediatrics. doi:10.1542/peds.2016-1211 ✓The AAP recommends pediatricians routinely screen adolescents and deliver SBIRT as part of preventive care.
  6. 6.National Institute on Drug Abuse (NIDA) (2014). Principles of Adolescent Substance Use Disorder Treatment: A Research-Based Guide. National Institute on Drug Abuse (NIH). link ✓Adolescence is a key developmental window for substance use disorders, and adolescent treatment should be developmentally tailored.

6 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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