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Cannabis is a plant known for its psychoactive properties. It is legal in Canada but is a controlled substance that has certain laws and regulations for its use. Cannabis contains over 140 cannabinoids – chemicals that affect how our brain functions and affects our mental state and physical movements.  Common names for cannabis include marijuana, weed, and pot among many others.  

About Cannabis

Cannabis is a plant that some people use to feel different. The part of the plant that can make people feel high is a cannabinoid called THC (tetrahydrocannabinol). Some people use cannabis to feel relaxed or happy. People can smoke it, vape it , eat it, or use other ways to take it. However, using cannabis can have some negative effects on your health, especially if you are young. It can harm your memory, attention, and learning abilities. Using cannabis can also make it harder for you to do things such as driving, sports, or other activities that require coordination. It’s important to talk to someone you trust if you have any questions or concerns about cannabis and your health.  

THC (tetrahydrocannabinol) and CBD (cannabidiol) are cannabinoids, chemical compounds found in cannabis. Cannabinoids change how signals are sent in our brains and affect our mental and physical state.  

THC is found in higher concentrations in non-medical cannabis. It is the main psychoactive compound of cannabis, meaning it changes our brain function and our ability to think, our mood, and our behavior.  

CBD is found in higher concentrations in medical cannabis. It is mainly used for its therapeutic effects for reducing pain and inflammation, nausea, anxiety, seizures, and spasms.  

Cannabis use can cause unpleasant, unwanted or negative effects on your brain and body, including: 

  • confusion and difficulty concentrating, 
  • anxiety, fear or panic, 
  • psychotic episodes of paranoia, delusions or hallucinations, 
  • poor co-ordination and slow reaction time, 
  • increased risk of injury (e.g., motor vehicle collision, falls), 
  • sleepiness, 
  • coughing, wheezing, 
  • shortness of breath, 
  • decreased blood pressure (risk of fainting or passing out), 
  • increased heart rate (increased risk of heart attack), or 
  • hyperemesis syndrome (uncontrollable vomiting). 

What are the harms of cannabis use if I use it over a long period of time? 

Long-term effects develop over time with daily or near-daily use over weeks, months or years. The effects can last from several days to months or longer after you stop using cannabis. For those who begin consuming cannabis at a young age (i.e. under 25) or use often, the following effects may become permanent: 

  • addiction (Cannabis Use Disorder), 
  • depression or anxiety, 
  • schizophrenia or other psychosis, 
  • harms to memory and concentration, 
  • lowering of intelligence or IQ, 
  • negative effects on your ability to think and make decisions, 
  • chronic (long-term) cough (when smoked), 
  • increased mucus buildup in the throat (when smoked), 
  • bronchitis (when smoked), or 
  • lung infections (when smoked). 


Edible cannabis products have many different appearances and ingredients, including how much THC and CBD are in them. Most cannabis edibles look like regular food items such as candy and chocolate. 

The effects of eating cannabis can be very different from inhaling (smoking or vaporizing) cannabis, The effects of cannabis can be delayed up to 2 hours after eating an edible cannabis product. Eating too much THC can cause anxiety and panic, nausea and vomiting, and symptoms of psychosis or paranoia. Follow these guidelines to lower your risks if you choose to eat cannabis: 

  • Make sure to read the label carefully and understand the potency of the product. The label should also indicate the recommended serving size. 
  • Don’t mix with alcohol or other drugs as this can increase the risk of negative effects. 
  • Avoid driving or operating heavy machinery. It’s important to wait until the effects have worn off. 
  • Be aware that edibles can cause side effects such as dizziness, nausea, and anxiety. If you experience any negative effects, stop consuming the product and seek medical attention. 
  • Keep all cannabis products in child-resistant packaging and in a locked area. Keep it out of sight and reach from children and pets.  
  • Cannabis in food products is very dangerous to children. Children may mistake these products for regular food such as brownies and cookies and eat them.  
  • If a child eats cannabis, they can become very sick. Get medical help right away.  
  • If your child ingests cannabis, call the Ontario Poison Centre (1-800-268-9017) or 9-1-1 immediately.  

The Government of Canada has Federal Cannabis Laws, including the Cannabis Act that made cannabis a legal controlled substance in 2018. Each province or territory also has its own cannabis laws. Make sure you know Ontario’s Cannabis Laws to help keep you safer if you choose to use cannabis. 

Cannabis-impaired Driving

Driving while high is illegal and it increases your chances of being in a car crash. Cannabis use alters the skills you need to drive such as quick thinking, decision-making, reaction time, and concentration. Learn more about the Myths and Facts of Impaired Driving from the Ministry of Transportation. 

For more information about Cannabis visit: Cannabis in Canada - 

Youth and young adults under age 25 who use cannabis are at higher risk of effects on brain development and function that may become permanent. This is because the brain continues to develop until the age of 25 and the THC in cannabis affects the same areas in the brain that direct development. 

Young people who use cannabis are at higher risk of: 

  • mental illness (depression, anxiety, schizophrenia or other psychosis), 
  • addiction (Cannabis Use Disorder), 
  • problems with memory, thinking, learning, problem-solving skills, 
  • behavioral issues, 
  • difficulties with relationships at home, school or work, and
  • lung and respiratory problems from smoking cannabis. 

Young people who use cannabis may be tempted to use it with other substances such as alcohol, which intensifies the effects and can lead to more health risks and worsening judgment leading to reckless behavior (such as driving while impaired, having unprotected sex, or other risk-taking behaviors). 

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