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After alcohol, cannabis is the most commonly used psychoactive drug in Canada.

Cannabis, also known as marijuana (also mary jane, hash, blunt, dab, joint) is a product of the plant cannabis sativa. The main active chemical in cannabis is THC (delta-9-tetrahydrocannabinol). THC is a psychoactive chemical that gives a high or feeling of euphoria to those who use it. Another active chemical in cannabis is CBD (cannabidiol), which is presently being studied and used for medical purposes. It does not have psychoactive properties.

Cannabis consists of the dried flowers, fruiting tops and leaves from the marijuana plant. It is commonly greenish or brown color. Cannabis resin (or hashish) is a brown or black secretion. It can be processed further to produce hash oil, wax or ‘shatter’. Shatter is a concentrated extract with very high levels of THC.

How will legalization in Ontario affect me?

The legal minimum age in Ontario is 19 years old, to purchase, use, possess (maximum of 30g on your person at any time in public) and grow cannabis. This is the same as the minimum age for the sale of tobacco and alcohol in Ontario. For more information including places of non-medical cannabis consumption, check out Ontario’s website:

For more health and legalization information about cannabis:

#1 – Myth – Cannabis is natural.

Fact: Just because it’s natural doesn’t mean it is safe. The cannabis plant contains compounds that can impair your normal behaviour. This can increase your risk of injury. Early onset and frequency of use – before the age of 25 – can impede normal growth and development of your brain. Smoking burnt cannabis, especially when combined with tobacco, can harm your lungs and respiratory system. Second hand and third hand smoke have risks for the health of those around you especially infants, young children and older adults. Exposure to these air borne toxins affect alertness, understanding and judgement.

#2 – Myth – Cannabis is not addictive.

Fact: Cannabis is addictive. After regularly using cannabis for a long period of time, people can develop physical dependence. If they stop using, they may experience mild withdrawal. Symptoms can include irritability, anxiety, upset stomach, loss of appetite, sweating and disturbed sleep. These symptoms generally last for about a week, but sleep problems may continue longer.

#3 – Myth – It’s safe to drive after using cannabis.

Fact: It is illegal to drive while impaired by any drug including cannabis. Cannabis impairs cognition, attention, reaction and psychomotor control – all of which are critical skills for driving or operating machinery. It is recommended that users categorically refrain from driving (or operating other machinery or mobility devices) for at least 6 hours after using cannabis. This wait time may need to be longer, depending on the user and the properties of the specific cannabis product used.

Impaired is Impaired.

Youth are most vulnerable: Many car crashes involving teenagers are caused by inexperience and poor judgment. When these factors are put together with alcohol, cannabis or other drugs, the results can be tragic.

Short term effects of cannabis include feeling happy, relaxed, increased heart rate, decreased attention span, slowed reaction time, nervousness, paranoia, body tremors, distorted perception (sights, sounds, time, touch), loss of motor coordination and anxiety. These effects may be even greater when other drugs are mixed with cannabis.

Potential long term effects of cannabis use:

  • Physical and mental health problems (including psychosis)
  • Decreased cognitive functioning (memory, attention, problem solving)
  • Reproductive health issues
  • Increased risk of addiction
  • Lung health issues

For more information:

Cannabis has been linked to many health and social problems. This is especially true with youth and frequent users. Research has shown that cannabis use can negatively affect a person’s life including:

  • physical and mental health problems
  • decreased cognitive functioning (memory, attention, and problem solving)
  • impair the ability to drive a vehicle
  • reproductive health issues

Clearing the Smoke on Cannabis Highlights – Canadian Centre for Substance Abuse

Clearing the Smoke on Cannabis: Maternal Cannabis Use during Pregnancy

Cannabis use and Adolescents – Canadian Centre for Substance Abuse

Society of Gynecologists and Obstetricians

The SOGC Urges Canadians to Avoid Cannabis Use During Pregnancy and Breastfeeding

Cannabis and Canada’s Children and Youth – Canadian Paediatric Society

Youth and Young Adults

Exposure to THC (the psycho-active component of cannabis) can have a negative and irreversible impact to the development of the adolescent brain. Regular or frequent use of cannabis (daily or near daily) has been associated with an increased risk of depression and anxiety disorders. Continued chronic cannabis use by individuals who initiate use at an early age is associated with cognitive and neuropsychological deficits, negatively impacting their future mental health. Deter or delay early onset of cannabis use until after 25 years of age is safest for brain development.

What you can do as a parent, guardian or caregiver of youth?

Preconception (Fertility), Pregnant, and Breastfeeding Persons

Studies have shown that cannabis use can affect your ability to get pregnant. Using cannabis during pregnancy causes the toxins to be carried through the mother’s blood to her fetus. Smoking reduces the supply of oxygen to the fetus. Once born, the baby may be of low birthweight, have reduced alertness and slower growth. Cannabis use during pregnancy has also been associated with longer-term developmental effects in children and adolescents, such as: decreases in: memory function, the ability to pay attention, reasoning and problem-solving skills, hyperactive behaviour and increased risk for future substance use. THC passes into the breast milk and to the baby’s fat cells and brain and can be stored for weeks. Some studies suggest that this exposure can lead to slower motor responses in baby.

What can you do to protect your health and your family’s health?

History of Mental Health Issues

Personal or family history of mental health problems increases the risk of dependency and of developing mental health problems.

Talk to your health care practitioner and take steps to protect your health.

Canada’s Lower-Risk Cannabis use Guidelines

  1. Abstain from use
  2. Avoid early initiation of cannabis use (before age 16)
  3. Use cannabis with a low THC content and a higher CBD:THC ratio
  4. Avoid synthetics cannabinoids (“spice”)
  5. Avoid routes of administration that involve smoking combusted material (use vaporisers or edibles)
  6. Avoid deep inhalation or breath holding
  7. Avoid daily or near daily cannabis use
  8. Refrain from driving for at least 6 hours post using cannabis (there is some data to say more than 8 hours)
  9. People at higher risk for cannabis-related outcomes refrain from using it (predisposition to psychosis, substance use disorders, pregnant women with effect on fetus)
  10. Preventing high risk behaviours e.g., early onset use of high potency cannabis

Canada’s Lower-Risk Cannabis use Guidelines

Additional Information and Research

Centre for Addiction and Mental Health

Canadian Centre for Substance Abuse

Health Canada

Province of Ontario