Whole-Health Effects: How Substance Use and Addictive Behaviours Affect Teens

A note before you start

This lesson is about substance use and addictions. It gives facts, not judgments, and it does not describe how to use any substance. If substance use affects you or someone in your family, you are not alone and it is not your fault. You can talk to a trusted adult, call ConnexOntario (1-866-531-2600, free, confidential, 24/7, for substance use, gambling and mental health), or reach out to Kids Help Phone (call 1-800-668-6868 or text CONNECT to 686868, 24/7, free and confidential) or the 9-8-8 Suicide Crisis Helpline (call or text 9-8-8, 24/7). In an emergency, call 911.

More than "it's bad for you"

You've heard "drugs are bad" since elementary school. In Grade 10 we go further: how, exactly, do substances and addictive behaviours affect a teen's body, brain, feelings, relationships, goals and future, and where can a young person turn for help?

In Grade 10, the curriculum asks you to show that you understand the effects of substance use and addictive behaviours on health and well-being (C1.2), connecting physical, mental, emotional, social and spiritual health.

Remember from Grade 9

In Grade 9 you studied resilience and the protective and risk factors for substance use, and the social influences (friends, media, family, sports culture) on using prescription drugs, alcohol, tobacco, supplements and performance-enhancing drugs, and on gambling, gaming and eating disorders. Now we look at what the substances and behaviours actually do.

Common substances and their effects

• Alcohol is a depressant. It slows reaction time, judgment and coordination, raising the risk of injuries, unsafe sex, fights and impaired driving. Large amounts in a short time can cause alcohol poisoning, which can be fatal. Over time, it is linked to liver disease, several cancers and mental health problems. Canada's Guidance on Alcohol and Health says young people should delay drinking as long as possible.
• Cannabis (its main active ingredient is THC) can affect memory, attention and learning, coordination and reaction time. Regular use that starts young is linked to a higher risk of addiction and of mental health problems, including psychosis in some people. Edibles can take 30 minutes to 2 hours to be felt, so people sometimes take more and get much stronger effects than they expected. Canada's Lower-Risk Cannabis Use Guidelines advise delaying use until after adolescence.
• Nicotine (in cigarettes and most vapes) is highly addictive, and teen brains are especially sensitive to it. Smoking causes lung disease, heart disease and cancer; vaping can expose the lungs to harmful chemicals.
• Opioids (including some prescription pain medications and fentanyl) slow breathing. Street drugs and fake pills may contain fentanyl that can't be seen, smelled or tasted, so even a small amount can cause an overdose.
• Prescription and over-the-counter drugs are safe only when used as directed for the person they were prescribed to.
• Caffeine (energy drinks): too much can cause a racing heart, anxiety and poor sleep. Health Canada advises teens to have no more than 2.5 mg of caffeine per kg of body weight per day.

Using more than one substance at a time (for example, alcohol and cannabis) increases the risks.

Addictive behaviours

• Gambling (including online sports betting, which you must be 19 to do legally in Ontario) can lead to debt, stress, lying and conflict. Starting to gamble young is linked to a higher risk of gambling problems later.
• Gaming and internet use become a problem when they take over sleep, school, friendships and other activities. The World Health Organization recognizes gaming disorder as a health condition.
• Features like loot boxes and in-game purchases are designed to keep people playing and spending.

The 4 Cs of addiction apply to behaviours too: craving, loss of control, compulsion, and continuing despite consequences.