Cannabis health information

Cannabis can be used for medical or non-medical purposes. People may choose to use cannabis for its therapeutic effects. But it can also harm your health. Cannabis affects everyone differently.

According to the Canadian Cannabis Survey 2020, 29% of British Columbians surveyed reported consuming cannabis within the past 12-months. But cannabis use does carry some health risks. These risks vary by age of user, consumption method and context of use.

Using cannabis may carry health risks and these risks increase with regular use. Cannabinoid hyperemesis syndrome is a condition that causes persistent nausea and stomach pain that can cause frequent vomiting and weight loss. The Canadian Centre on Substance Use and Addiction (CCSA) has collaborated with other organizations to produce a new resource about the syndrome, Frequent vomiting from use of cannabis. The resource provides information about cannabinoid hyperemesis syndrome, the health risks associated with the condition and options for its treatment and prevention.

Learn more about the health risks and guidelines for safer use:

For information about the health effects of vaping, please visit the BC Lung Association or HealthLink BC.


Edible cannabis products may look like regular foods such as baked goods (brownies, cookies), drinks, chocolates or candies, but they aren’t. Many cannabis edibles contain THC and overconsumption can cause adverse effects and/or accidental poisoning, especially if eaten by a child or pet.

Check out these resources to learn more about the three new classes of cannabis or visit Health Canada’s website:

Edible cannabis quick tips

  • Start with small amounts: 2.5 mg of THC or less for products that you eat or drink
  • Don’t take more right away – effects from an edible cannabis product may not be felt for two hours, and it may take four hours for effects to peak
  • Clear your schedule – the effects from edible cannabis last 4 to 12 hours with some effects lasting up to 24 hours
  • Label and store all cannabis securely. Edible cannabis can look like regular food such as baked goods or candy; to reduce the risk of accidental consumption label your cannabis edibles and store them securely away from food products and out of the reach of children and pets.
  • Obtain cannabis and cannabis products from a legal source.
  • If you or someone you know has accidently consumed cannabis or consumed too much cannabis and is not well, seek immediate assistance:
    • Call BC Poison Control Centre: 1-800-567-8911 or 604-682-5050
    • If symptoms are severe, call 911 or go to your local hospital emergency department

It can take anywhere from 30 minutes to two hours to begin to feel the effects of edible cannabis and up to four hours to feel the full effects. The intoxicating effects can last up to 12 hours, with some residual effects lasting up to 24 hours. The psychoactive effect of edible cannabis has a relatively slow onset which may increase the risk of overconsumption.

How soon and how long a person experiences the effects of edible cannabis depends on individual factors including weight, metabolism, sex, and whether the cannabis is eaten on an empty stomach. 

If you choose to consume cannabis, how much you consume and how quickly you consume can influence whether or not you experience adverse effects. Many people are aware of the immediate psychoactive effect associated with smoking cannabis but may not be aware of the delayed onset and the extended duration of the effects associated with edible cannabis.

Using low dose products containing no more than 2.5mg THC may assist you in determining your individual response to and comfort level with the effects of edible cannabis. This careful small-dose approach will help you avoid overconsumption that can result in unpleasant effects including extreme sedation/inability to move, anxiety, paranoia, hallucinations, delusions, rapid heartbeat or respiratory depression.

Non-medical cannabis legalization has increased the use of cannabis among adults and increased the likelihood of accidental consumption by children, unsuspecting adults, and pets. It is important for adults to store cannabis products out of sight and reach from children in the home.

If you or someone you know has accidently consumed cannabis or consumed too much cannabis and is not well, seek immediate assistance:

  • Call BC Poison Control Centre: 1-800-567-8911 or 604-682-5050
  • If symptoms are severe, call 911 or go to your local hospital emergency department

Safety tips to protect children from cannabis poisoning:

Research about cannabis poisoning in Canada:

Not using cannabis during pregnancy and while breastfeeding is the safest option for you and your baby until we can learn more from research about the effects. Here is what we currently know:

In pregnancy

Cannabis use during pregnancy may harm your baby. It has been associated in some studies with:

  • Low birth weight
  • Longer term developmental effects for children and youth – affecting memory, attention span, reasoning and problem-solving skills, and hyperactivity
  • Increased risk for future problematic substance use

Some pregnant women wish to use cannabis for morning sickness, anxiety or pain. There are alternative treatments for these health issues. Please speak to your health care provider about the options.

When breastfeeding

Chemicals from cannabis are also passed through breast milk, and may have negative short and long term health effects – in the short term affecting the infant’s ability to nurse, and in the long term affecting development.

At the very least, avoid breastfeeding within one-hour of inhaled use, to reduce exposure to highest concentration of cannabis in breast milk.

Learn more about the health risks of cannabis use, including during pregnancy and while breastfeeding: