Cannabis it the second most commonly used substance by youth

After alcohol, cannabis is the most common substance by youth and adults in Canada. However, the 2018 BC Adolescent Health Survey found that 75 per cent of youth had never tried cannabis. Not all youth choose to use substances. 

How does cannabis work?

Cannabis is a plant that contains chemicals called cannabinoids. Two of the main cannabinoids in cannabis are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the psychoactive compound that affects how people think and behave, commonly referred to as feeling “high”. CBD is a non-psychoactive compound found in cannabis that some people use to manage certain symptoms, although research is limited for the use of CBD for most medical conditions.

How is cannabis consumed and what are the health risks?

Cannabis is most commonly used via smoking, vaping, or ingesting (e.g. edibles).


Smoking cannabis leads to a rapid onset of effects, typically within 5-10 minutes. The acute effects of cannabis may last 2-6 hours. Smoking cannabis is associated with an increased risk of cough, sputum production, wheezing, and shortness of breath. Smoking cannabis long-term increases the risk of chronic bronchitis, airway inflammation, and lung disease. Smoking cannabis is likely the most hazardous method of cannabis consumption and smoking cannabis around others can expose them to the harms of second-hand smoke. Additionally, cannabis and tobacco are often used together, which can further impact respiratory and cardiovascular health. Taking deep breaths or holding the smoke in the lungs also increases the risk to lung health.


Vaping cannabis has a similar onset and duration of effects as smoking cannabis. While vaping generally results in less exposure to toxic chemicals than smoking, we do not know all of the chemicals people are exposed to when vaping and vaping is not harmless. Cannabis vaping products may contain several harmful contaminants, some of which include: pesticides, residual solvents, heavy metals, bacteria, and fungi. In particular, vitamin E acetate has been found in some vaping products and is linked to vaping associated lung illness (VALI), an acute respiratory illness resulting from lung damage. Vape juice can have high levels of THC. High potency THC and heavy cannabis use raises the risk of acute adverse effects, such as paranoia, psychosis, and cannabis hyperemesis syndrome (severe nausea and vomiting).

Ingesting (eating and drinking)

When cannabis is consumed, the onset of effects is usually 1-2 hours or more. Effects last longer than inhaling cannabis, often 6-12 hours or more. This delayed onset can increase the risk of people unintentionally overconsuming, resulting in over-intoxication.  Overconsumption can lead to cannabis toxicity, which can present as chest pain, rapid heartbeat, severe nausea/vomiting, psychotic episode, respiratory depression, and severe anxiety and/or panic attacks. Cannabis edibles are of particular concern for children and youth as they may mistake them for candy or sweets.

Legalization does not mean cannabis use is harmless. Avoiding cannabis completely is best.

The most effective way to avoid all risks of cannabis is to not use it. Although cannabis is sometimes perceived as a relatively safe drug, it has well-documented immediate and long-term health risks. Harms associated with cannabis can include: acute intoxication, increased involvement in motor-vehicle crashes, impaired functioning, mental health problems (e.g., psychosis and schizophrenia, depression and suicidal behaviors), cannabis use disorder as well as respiratory, reproductive, cardiovascular, and gastro-intestinal conditions.

If choosing to use, wait as long as possible

Youth who initiate cannabis use early, primarily before 16 years, have increased risk for poor health and social outcomes because cannabis impacts the developing brain. In fact, brain development continues into the mid- to late-twenties. Risks from early onset include: injury, mental health issues (mood swings, anxiety and depression, suicide), academic difficulties, and other substance use problems. The risk increases for youth who use high potency products and for those who use heavily and frequently. Further reduce risks by choosing lower THC products, not smoking it, avoiding deep inhalation and heavy and frequent use. Delaying cannabis as long as possible will support health and welfare throughout later life.

How to support youth to prevent, delay or reduce cannabis use

Youth who feel connected to their family, school, and community are less likely to use cannabis. It is important to talk to youth about substance use.

  • Have open and honest conversations. Avoid lecturing and judging youth.
  • Have clear, but caring boundaries and family guidelines about cannabis use.
  • Ensure that youth feel safe and supported.
  • Seek out factual information to share with youth.
  • Let youth know that not everyone chooses to use cannabis or other substances. All substance use has inherent risk for harm.
  • Be a positive role model by demonstrating responsible behaviour and avoiding cannabis use or any other substance, especially when youth are present.
  • Promote healthy coping skills for dealing with stress, anxiety and other challenges.



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