Cannabis use

Lower-risk cannabis use and overconsuming cannabis.

Consuming cannabis

Cannabis can be consumed in different ways. Two common ways are inhalation (smoking or vaping) and ingestion (eating or drinking). Each way carries different risks to your health and your safety.  

Whether cannabis is inhaled or ingested will influence when and for how long the effects (intoxication or feeling ‘high’) of cannabis are felt.

Inhalation (smoking or vaping) 

When cannabis is inhaled into the lungs it passes directly into the bloodstream and then the brain.  

The effects are usually quickly felt by the brain and body, from seconds to within minutes of inhaling. The full effects from one inhalation can take up to 10 to 30 minutes to peak. Consuming more within this time can increase the risk of adverse effects.  

The effects of cannabis inhalation can last up to 6 hours after use. Some remaining effects could last up to 24 hours after use.

Ingestion (eating or drinking)

When cannabis is ingested, it travels to the stomach first, then to the liver before getting into the bloodstream and brain. The body turns it into a stronger form called 11-hydroxy-THC.   

Since it takes longer to be absorbed into the bloodstream, it can take 30 minutes to 2 hours for the effects to be felt by the brain and body.  The full effects can peak up to 4 hours after ingestion.  Consuming more within this time can increase the risk of adverse effects.  

The effects of cannabis ingestion can last up to 12 hours after use. Some remaining effects could last up to 24 hours after use.

Knowing your limits with cannabis

A practical guide to assessing your cannabis use by the Canadian Centre on Substance Use and Addiction (PDF)

7 things you need to know about edible cannabis

Developed by the Canadian Centre on Substance Use and Addiction (PDF)

What you need to know if you choose to consume cannabis

Developed by the Government of Canada (PDF)

Choose legal cannabis

Learn to recognize the differences between legal and illegal cannabis and find out why it matters.

Lower risk cannabis use

There are risks associated with cannabis use. The best way to protect your health is to avoid using cannabis or cannabis products completely.

To lower your risk of the harmful effects of cannabis, it helps to know the differences between the two most common ways of consuming it: inhalation (smoking or vaping) and ingestion (eating or drinking). Each way carries different health and safety risks.

Everyone's response to cannabis is different, depending on:

  • sex 
  • age
  • THC and CBD content
  • any pre-existing medical conditions
  • experience with cannabis, frequency of use 
  • consumption of food, alcohol, other drugs, or health products

Everyone's response to cannabis can also differ from one time to the next.

Research suggests that there are ways to reduce the risks:

  • Use it in a safe and familiar environment and with people you trust, especially if you are inexperienced or a new user. 
  • Delay cannabis use until the brain is fully developed. This occurs around the age of 25.
    • The earlier you begin using cannabis, the higher your risk of serious health issues, including dependence and other mental health problems.
  • Choose a product with equal or higher amounts of CBD than THC.
    • The higher the THC content of a product, the more likely you are to experience adverse effects and greater levels of impairment. CBD is known to reduce some of the effects of THC. 
  • If you smoke cannabis, avoid inhaling deeply or holding your breath.
  • Limit and reduce how often you use cannabis.
    • Frequent use of cannabis over a long time can contribute to mental health problems. These include dependence, anxiety, and depression. 
  • Avoid mixing cannabis and other substances, like alcohol or drugs. 
    • Using cannabis at the same time as drinking alcohol and/or using other drugs can cause more severe levels of impairment and adverse effects. Other drugs include pain medications (opioids) and tranquillizers (benzodiazepines).
  • Avoid using cannabis and driving or operating machinery.
    • After alcohol, cannabis is the drug most often linked to car accidents. Cannabis can affect your concentration, attention, and coordination, and slow your reaction time. Using it and driving or operating machinery increases the risk of having an accident, which can result in serious injuries or death.
  • Avoid using synthetic cannabis products, which are illegal. 
    • Products known as synthetic cannabis (K2, spice) are not cannabis at all. These products are very different, have much stronger effects and are more dangerous. Using synthetic cannabis can lead to severe health problems, such as seizures, irregular heartbeat, hallucinations and, in rare cases, death.
  • Avoid cannabis completely if you are at risk for mental health problems, especially
    • psychosis
    • schizophrenia 
    • problematic substance use

For more information, please see the lower-risk cannabis use guidelines developed by Canadian experts in mental health and addiction.

Overconsuming cannabis (Cannabis poisoning)

Consuming too much cannabis at one time or accidentally consuming cannabis can lead to over-intoxication or cannabis poisoning. 

It can be very unpleasant and potentially dangerous, sometimes requiring emergency medical attention and, in some cases, hospitalization. The effects, however, are usually temporary and are not known to be fatal.  

Pay attention for symptoms of over-intoxication which can include:

  • severe anxiety and panic 
  • nausea and vomiting
  • psychosis and paranoia (i.e., hallucinations and delusions)
  • lower rate of breathing (respiratory depression)
  • chest pain 
  • rapid heartbeat

Anyone who has consumed cannabis and is not feeling well or is experiencing symptoms of over-intoxication should

  • immediately stop using the cannabis product
  • call 911 right way for medical help and poison information or Telecare 811 for medical advice 

Legally sold cannabis products will be marked with a label, which will have the amount of THC and CBD they contain, and health warnings listed. Always read the label to check the amount and concentrations of THC (tetrahydrocannabinol) and CBD (cannabidiol) to understand the strength of the product being used.

The higher the THC content in a product, the more likely it is to experience adverse effects/poisoning, especially for people who are inexperienced with cannabis or are using cannabis for the first time. 

It is easier to be poisoned when ingesting (eating or drinking) cannabis compared to inhaling cannabis (smoking or vaping). 

  • It can take much longer to feel the effects of a product that has been ingested. The result is that people consume more before they feel the full effects. 
  • Some of these cannabis products may be mistaken for regular food or drinks (non-cannabis products). 

Children and pets are at greater risk of accidental cannabis consumption and cannabis poisoning. The effects of cannabis are stronger and last longer for children. To prevent them from being harmed, store all cannabis products safely locked, and keep them out of reach of children, youth, and pets.