Marijuana: What parents need to know

Marijuana is the most commonly used drug by Canadians between 15 and 24 years old. Even though some young people think marijuana is harmless, it actually has serious risks. Because the bodies and brains of young people are still developing, marijuana can be harmful to them. Used regularly, marijuana can trigger changes and damage to the brain. Marijuana also impairs judgment and coordination, so users are at higher risk of injury, especially if they use it while (or before) driving.

What is marijuana?

Marijuana is the drug made from the flowered buds, leaves and stems of the Cannabis plant. Marijuana goes by many names, like pot, weed, dope, grass and Mary Jane. Marijuana is most commonly smoked, but it can also be vaped with an e-cigarette, or infused into foods.

What are the short-term effects of marijuana?

When marijuana is smoked, THC (the main active chemical in cannabis) goes from the lungs into the bloodstream and the brain, causing a “high”. Short-term effects can include:

  • a sense of euphoria, feeling intense happiness and relaxation,
  • difficulty thinking and problem solving,
  • short-term memory loss,
  • lack of coordination,
  • distorted perception,
  • hunger,
  • lightheadedness or drowsiness,
  • paranoia and/or anxiety.

Using marijuana before or while driving makes a person more likely to be in a collision.

What are the long-term effects?

A young person’s brain continues to develop into their early 20s. Using marijuana regularly can cause brain changes and permanent brain damage.

Long-term, regular marijuana use has been associated with a variety of problems and risky behaviours.

Mental health:

  • Depression
  • Anxiety
  • Psychotic illnesses (losing touch with reality)

School performance:

  • Difficulty concentrating, remembering things, and solving problems
  • Falling behind in class
  • Grades dropping
  • Dropping out of school

Substance abuse:

  • Heavy drinking
  • Cigarette smoking

Cancers and lung disease

  • Cancers of the lung, esophagus, mouth, throat, kidney, bladder, pancreas, and stomach
  • Chronic bronchitis and emphysema

Over the past few years, experts have observed withdrawal symptoms from quitting marijuana, which indicate that marijuana can be addictive. Marijuana currently available on the streets is 2 to 4 times stronger than it was in the 1970s.

How do I know if my child is using marijuana?

Some signs to look out for:

  • Spends less time with friends and family, or has a recent change in friends
  • Seems moodier
  • Skips classes or his grades are slipping
  • Loses interest in hobbies/sports
  • Has red or glassy eyes, at times
  • Smells like marijuana (skunky)
  • Owns pipes, bongs, rolling papers, etc.
  • Suffers regular injuries

Is it safe to drive while or after using marijuana?

No. Like alcohol, marijuana impairs your judgment and coordination. It makes it difficult to stay in your lane, judge speed and time.

How can I protect my younger children?

If you use any form of marijuana, keep it well out of reach of children. Younger children can accidentally ingest marijuana or marijuana-infused foods that look like desserts or candy.

Unintentional ingestion can cause overdose symptoms like severe drowsiness and breathing problems. If this happens, your child needs urgent medical care and may need to be hospitalized.

What can I do if my child uses marijuana?

  • Don’t panic.
  • Let your child know that you care and that you want to make sure that they have correct and up-to-date information about the risks of using marijuana and the problems it can cause.
  • Have an open discussion about the risks of marijuana on their developing brain.
  • Make sure they understand the dangers of driving after or while smoking marijuana.  
  • A health professional like your family doctor or paediatrician can help as well. The Canadian Paediatric Society recommends that young people do not use marijuana.

More information from the CPS:

Additional resources:

Reviewed by the following CPS committees:

  • Adolescent Health Committee



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