Missing cash from your wallet has plenty of possible explanations. Your teenager might be saving for a gift or trying to impress a friend group. Sometimes, though, those missing bills point to something more serious, and this guide focuses on that possibility. Rather than covering normal teenage growing pains, you’ll find the specific signs that point to substance use, along with paths toward support for your family.
The University of Michigan and the National Institute on Drug Abuse track this closely through their Monitoring the Future survey. According to their 2025 data, 16% of tenth graders used cannabis in the past year. Among high school seniors, that figure climbs to 26%.
In this article, you’ll find out how to spot specific physical symptoms without assuming the worst.
- Moodiness, privacy and more time with friends are normal; extreme changes or a break from who your teen has always been deserve attention.
- A pattern of several signs together matters more than any single sign.
- Physical signs vary by substance, and more than one set of signs can show up together.
- Calm, private conversations with open-ended questions work better than confrontation.
- Early intervention leads to better outcomes than waiting until a crisis forces the issue.
What’s Normal Adolescent Behavior vs. a Warning Sign
Hormones and a developing brain make teenagers moody, private and occasionally rude, and that alone fits within the normal range. However, wanting more time with friends than family or needing hours alone in their room is part of growing up, and so is testing a few limits along the way.
The line gets crossed when these patterns turn extreme, or when they pair with a change that breaks from who your teen has always been. A once easygoing kid turning secretive, or a top student suddenly skipping class, both fall into this category. Since you know your teen better than any checklist could, a pattern that feels off deserves your attention, even before it fits a textbook definition.
Behavioral Warning Signs
When substance use enters the picture, certain behavior changes show up again and again. For example:
- Pulling away from family events, or long stretches out of the house with no clear account of where they were
- Slipping grades, skipped classes or a sudden drop in interest in school
- A new friend group known for risky behavior or substance use
- More secrecy than usual, with stories that shift or contradict each other
- Losing interest in a sport, instrument or hobby they used to love
- Sleep patterns that swing between barely sleeping and sleeping for most of the day
Any single sign here could mean something else entirely. A pattern of several together is what deserves your attention.
Physical Warning Signs
Physical signs tend to stand out more than behavioral ones, though they still slip past you without a closer look. Alcohol and marijuana can leave eyes red and pupils larger than normal, while opioids like oxycodone or hydrocodone shrink the pupils to pinpoints.
Other physical signs of teen drug use might include:
- Sudden weight changes, either eating much more or barely eating at all
- Nosebleeds with no obvious cause, often linked to cocaine use
- Slipping hygiene, like wearing the same clothes for days or skipping showers
- Slurred speech or clumsy movement, especially after time away from home
Signs by Substance
Because every substance affects the body differently, you will notice specific physical changes. By looking for these distinct symptoms, you get a much better read on their current health.
Here’s what you need to know:
- Alcohol. The smell on breath or clothes, clumsy movement and a drop in inhibition around family
- Cannabis and vaping. A sweet or burnt smell, bloodshot eyes, snack cravings and vape devices that look like USB drives or pens
- Stimulants like cocaine or prescription amphetamines. Dilated pupils, rapid talking, restlessness and nosebleeds
- Opioids. Pinpoint pupils, drowsiness, slowed breathing and constipation
- Benzodiazepines, a class of sedative medications often prescribed for anxiety. Slurred speech, poor coordination and memory lapses
A teen dabbling in more than one substance at a time happens often, so more than one set of signs can show up together.
What You Might Find
Many parents notice something is wrong before they notice a change in their teen’s behavior. This often happens while doing laundry or searching for a charger, when an item in the room seems out of place or unexplained. The list below covers what tends to catch most parents’ attention first.
- A vape pen on the desk, easy to mistake for a USB stick until you pick it up
- A baggie pushed to the back of a drawer, or rolled paper with no obvious use
- A pill bottle that doesn’t match what’s on the label
- A spoon with burn marks, or a pen that’s been hollowed out
- Eye drops stashed in the bottom of a backpack
Why Teens Start Using
A buildup of small pressures, rather than one sudden decision, usually pushes a teen toward drug use. The sections below cover some of the main reasons this happens.
Peer Influence and Social Media
Fitting in matters enormously at this age, and a friend group already using can make saying no feel harder than saying yes. Social media adds another layer, since posts and videos can make substance use look glamorous or harmless. A teen who fears getting left out often goes along with something they would otherwise skip.
Mental Health and Self-Medication
Anxiety, depression and stress push some teens toward substances as a way to feel normal, even for a few hours. A teen dealing with an undiagnosed mental health condition might reach for alcohol or drugs long before a parent notices anything is wrong. Treating the substance use works best when it happens alongside care for the mental health condition underneath it.
Access at Home
Medicine cabinets, liquor cabinets and old prescription bottles give teens an easy starting point. A supply sitting unused in a bathroom drawer can look like a low-risk way to try something new. Locking up medications and alcohol removes one of the simplest paths to first use.
How to Talk to Your Teen
Bringing up drug use goes best in a calm moment, chosen with care rather than triggered by an argument or a fresh discovery. Pick somewhere private and low pressure, like a car ride or a walk.
- Ask open-ended questions instead of ones that invite a quick yes or no
- Listen more than you talk, and let your teen finish a thought before responding
- Share real information about how drugs affect the brain and body, rather than warnings alone
- Offer to help them find support, like a school counselor or an outside professional
Your tone matters as much as your words. A teen who feels judged tends to shut down, while one who feels heard is far more likely to open up again later.
What to Do If You Suspect Use
If you notice several signs lining up, address it directly instead of waiting for more proof. A journal noting dates, behaviors and anything you find helps you track whether things improve over time. Set clear expectations about substance use in your home, and talk through them with your teen rather than announcing them after the fact.
Drug Testing at Home
At-home drug tests are available at most pharmacies and can offer a quick answer, though results have limits and can miss certain substances or time windows. A positive result works best as an opening for conversation rather than a punishment.
When to Get a Professional Assessment
A school counselor, pediatrician or addiction specialist can assess how serious your teen’s substance use has become and guide you toward the right next step.
Research on adolescent treatment consistently shows that early intervention leads to better outcomes than waiting until a crisis forces the issue.
Treatment Options for Teens
Treatment for teens looks different from adult programs, since it accounts for a still developing brain and often involves the whole family. Options usually include outpatient counseling for teens who can stay at home, and residential programs for teens who need a higher level of structure.
Family therapy often runs alongside individual counseling, since a teen’s recovery tends to go further when the people around them know what is happening and how to help. Early treatment gives a teen the best shot at building healthy habits before substance use becomes a lasting pattern.
Supporting Yourself as a Parent
Watching a teen struggle with substance use takes a toll on you too, and people often overlook that part. Talking to a therapist or joining a support group for parents gives you somewhere to process what you are feeling instead of carrying it alone. Taking care of your own health, sleep and stress levels puts you in a better position to help your teen through this. A parent running on empty has less to give, and your teen needs you steady more than perfect.
Frequently Asked Questions
Where to Find Help
If you are noticing signs of teen drug use in your home, a pediatrician or school counselor is a good first call. They can assess what’s happening and refer your family to adolescent treatment. You can also search for licensed programs near you through SAMHSA’s FindTreatment.gov.
FHE Health treats adults 18 and older, including young adults facing substance use and mental health concerns. If your child is 18 or older, contact FHE Health to talk through what you are seeing and learn what help looks like.
