Cannabis is a plant that contains chemicals with psychoactive and therapeutic properties. Cannabidiol (CBD) is the chemical used therapeutically in medical cannabis products. Tetrahydrocannabinol (THC) has psychoactive properties which affect the brain (mind-altering). Cannabis products include the dried herb as well as hashish and hashish oil. Cannabis is also known by other names such as marijuana, weed and pot.


If you think a child has consumed any form of cannabis, call the Ontario Poison Centre at 1-800-268-9017 or call 911 immediately.


There are a number of immediate and long-term health concerns with consuming cannabis around children. To protect a child’s health and well-being, parents/caregivers should ensure cannabis is safely stored, and avoid using cannabis when caring for children. A non-impaired adult should always be present to take care of children.


  • Store all cannabis products in a locked area and in child-resistant packaging.
  • Make sure a child cannot see the cannabis or reach the locked area.
  • If you think a child consumed any form of cannabis, get medical help right away. Call the Ontario Poison Centre at 1-800-268-9017 or call 911 immediately.

Second-hand smoke

  • Second-hand cannabis smoke is harmful for everyone. It may result in illness in infants and young children, and can also affect their alertness, understanding and judgment.
  • It is safest not to smoke or vapourize (vape) cannabis in your home or around your child.


  • Cannabis impairment may affect how parents/caregivers interact with a child and reduce their ability to protect the child from harm.
  • Frequent cannabis use may negatively affect the parent-child relationship and attachment.
  • Impaired adults may miss a child’s cues for hunger or comfort.
  • A non-impaired adult should always be present to take care of children.

Cannabis for non-medical use is legal in Canada as of October 17, 2018. Under the new laws in Ontario, adults 19 years of age or older are able to:

  • purchase cannabis through a provincially authorized retailer
  • possess up to 30 grams of dried legal cannabis in public
  • share cannabis with people 19 years of age or older

The new legislation includes criminal offences for sharing/selling cannabis with/to minors and penalties for individuals who engage youth in cannabis-related offences.

Drug-impaired driving remains illegal in Canada. Law enforcement can currently detect drug-impaired driving using Standard Field Sobriety Testing and Drug Recognition Expert evaluation. Roadside Drug Screening Equipment has also been approved for use by law enforcement.

It remains illegal for travellers to take cannabis out of Canada or to bring it back from other countries.

The rules and regulations related to cannabis may be different in other provinces and territories.

The law on cannabis use for medical purposes is different and can be found at Health Canada.

Research shows that cannabis can be harmful to health if consumed frequently and to those who start using cannabis at a young age.

  • Cannabis impairs the mental ability to drive or use machinery safely for up to six hours or longer after use.
  • Frequent and heavy cannabis use can have significant effects on:
    • mental health (especially if there is a family history of mental illness)
    • adolescent brain development
    • cognitive (e.g. memory, attention span) and psychomotor functioning (e.g. motor coordination, and operative tasks)
  • Similar to tobacco smoke, cannabis smoke contains cancer-causing chemicals and other harmful by-products
  • Long-term, chronic cannabis smoking is linked to poor respiratory health, including:
    • increased coughing and wheezing
    • bronchitis

The only way to completely avoid the health harms associated with cannabis is to not consume cannabis. The potential health harms can be reduced by:

  • avoiding cannabis consumption during adolescence
  • not consuming cannabis if planning to drive to avoid impaired driving
  • limiting how often you consume and avoiding high-potency cannabis
  • not combining tobacco or alcohol with cannabis
  • consuming only small amounts of cannabis edibles and then waiting to feel the psychoactive effects, which may take up to two hours

Smoking anything, including tobacco and/or cannabis is harmful to lungs. Health Canada is monitoring the safety of using a vaporizer.

Pregnant individuals and individuals with personal/family history of psychosis should avoid cannabis use.


Related information:

Canada’s Lower-Risk Cannabis Use Guidelines

Legal Access to Non-Medical Cannabis: Approaches to Protect Health and Minimize Harms of Use

Drug-impaired driving is illegal in Canada.


Don’t drive high. If you have consumed cannabis, plan for a safe ride and avoid impaired driving.

Cannabis has been found to negatively affect the cognitive and psychomotor skills needed for driving including memory, attention and stop reaction time. This can significantly impact your ability to drive safely. Driving under the influence of both alcohol and cannabis causes greater impairment.

Law enforcement have the ability to detect drug-impaired driving using Standard Field Sobriety Testing and Drug Recognition Expert evaluation.

In Ontario, drivers who are 21 years of age or younger, and commercial and novice drivers are prohibited from driving with any amount of alcohol or cannabis in their system. Drivers breaking the zero tolerance rule may face immediate penalties including license suspension and potential criminal charges


Related information:

Ministry of Transportation


It is illegal for youth under the age of 19 to buy, sell or possess cannabis products.


The legal age limit for buying and consuming cannabis has been set at 19 years of age in Ontario. Early and frequent cannabis use during adolescence has been linked to a higher and longer-lasting health outcomes, including:

  • problems with memory and learning
  • having trouble thinking and problem solving
  • higher risk of developing psychosis which is a mental state in which you lose touch with reality

The potential risks associated with frequent cannabis use are higher during adolescence and up to age 25 while the brain continues to develop.

Youth who have supportive parents, teachers, and other adults in their lives are less likely to use alcohol and other drugs, including cannabis. When supportive adults create opportunities to talk about cannabis, it in itself is a protective factor against developing substance use issues.


Resources to help you talk to youth about cannabis:

Cannabis Talk Kit: Know how to talk with your teen

Kids Help Phone 

Individuals who are planning a pregnancy or are pregnant should avoid cannabis use and exposure to second-hand cannabis smoke.


Research shows that cannabis can be harmful to your health before, during and after pregnancy. There are no known safe limits of cannabis use during pregnancy or when breastfeeding.

Planning a Pregnancy

Frequent cannabis use can impact your ability to get pregnant. Studies have shown that using cannabis one or more times per day, is linked to:

  • changes to the menstrual cycle
  • lower testosterone levels, sperm count and sperm quality


Cannabis contains over 700 chemicals including THC and many of the same harmful chemicals as cigarette smoke. During pregnancy, these chemicals can pass from your body to your baby and may affect baby’s development.

Research shows that cannabis during pregnancy may increase the risk of:

  • pre-term birth
  • low birth weight

Some people have reported that using cannabis during pregnancy helps to manage morning sickness. However, due to the potential risks to the pregnancy, unborn baby and mother, safer approaches should be discussed with a health care provider.

THC is stored in human fat cells, including the fat cells in baby’s brain. Cannabis use during pregnancy may affect baby’s brain development which may result in learning and behaviour difficulties later in childhood.

Video: There may be a time and a place, but is pregnancy one? Canadian Institute for Health Research


Pregnancy to Parenting Blog: Health risks of cannabis use during pregnancy

Risks of Cannabis on Fertility, Pregnancy, Breastfeeding and Parenting 

Are you pregnant or considering pregnancy?

Individuals who are breastfeeding/chestfeeding should avoid cannabis use and exposure to second-hand cannabis smoke.


THC and other chemicals from cannabis pass from your breast milk to your baby. THC is stored in fat cells of the breast and can be released into breast milk for several weeks. These chemicals can lead to decreased milk production and may impact your baby by:

  • affecting baby’s brain development
  • causing drowsiness
  • making it harder for baby to latch properly due to poor muscle tone and poor sucking habits
  • affecting baby’s movement and responses

Pumping and throwing out your breast milk shortly after using cannabis will not prevent your baby from consuming THC the next time you feed your baby.

Breastfeeding is still the healthiest choice for your baby. Until more is known about the short and long-term effects of cannabis on your baby, it’s safest to avoid using cannabis while pregnant or breastfeeding.