Cannabis

Cannabis is a drug that can affect your mind and body. The physical and mental effects of cannabis vary depending on how much cannabis is used, how it is used, and what type of cannabis is used.

Choosing to use? Know the risks.

If you decide to use cannabis products, learn how to use it responsibly and reduce risks for yourself and others.

Cannabis affects everyone differently. Make sure you understand the health effects of cannabis.
Cannabis products that you eat or drink (edibles) can be more intense than inhaling cannabis, but the effects of it take longer to occur. Be patient and go slow. Learn more about edibles.
Choose edibles containing 2.5 mg or less of THC to avoid over-intoxication. Know your limits and learn more about THC.
Over-intoxication of cannabis (greening out) can take the form of anxiety, panic, nausea, vomiting and symptoms of psychosis, such as paranoia.
Alcohol increases the intoxicating and impairing effects of cannabis. It is safer to choose one or the other, not both.
Edible cannabis products often look like non-cannabis treats such as chocolate, brownies and gummies. Ensure cannabis products are securely stored away from children, youth and pets to prevent unintended cannabis poisoning.
Youth are especially vulnerable to developing dependence and problematic use of cannabis, as their brains are still developing.
Cannabis use while pregnant or breastfeeding may harm your child’s development. Learn more about the possible health outcomes.

Where to Get Help for Substance Use

Cannabis and health effects

Cannabis does not have the same effect on everyone and can lead to dependence. Cannabis can be harmful to mental and physical health.

When making decisions about using cannabis, it is important to consider the health effects. The effects of cannabis can be different for each person depending on genetics, how much cannabis is used, how it is used and what type of cannabis. It’s safest to start with low-strength THC and wait for the effects before consuming more.

While cannabis may make you feel relaxed and happy, you could experience unpleasant, unwanted or negative effects on your brain and body. Using cannabis can have health risks for everyone, but the risk is higher for youth, people with a family history of mental health challenges and people who are pregnant or breastfeeding.

For more information, see the health effects of cannabis from Health Canada.

Types of cannabis products

Edibles

Edibles refer to food or drinks that contain active cannabinoids (THC, CBD). The effects of edible cannabis take longer to feel and last longer than smoking or vaping. Legal edible products can have up to 10 mg THC per package. Start with 2.5 mg THC or less to minimize the risk of harm.

Since there may be a delay between the time of use and the time it takes to experience effects, this can cause a person to consume more in a short amount of time, resulting in over-intoxication. Over-intoxication can include symptoms of severe anxiety and panic, nausea and vomiting, and symptoms of psychosis (paranoia).

Topicals

Cannabis cream is put on the skin. Cannabis cream is usually higher in CBD and lower in THC and is generally used for medical purposes.

Extracts

Cannabis extracts like hash, kief, wax, or shatter contain a high concentration of THC. High THC products (over 30%) increase the risk of experiencing mental health challenges and dependence. High THC products can change how the brain grows, affecting performance and cognitive function.

Smoking

Leaves and buds from the cannabis plant can be smoked or vaped. Heating the leaves or buds activates the THC.

Find out more about the different forms of cannabis from Health Canada.

Minimizing risks and harms of cannabis

The safest choice is not to use cannabis at all. If you choose to use cannabis, you should understand the risks. For more information on how you can reduce your risk of experiencing harms, see Canada's Lower-Risk Cannabis Use Guidelines.

Start Low. Go Slow! After you use, wait to feel the effects.

Effects from smoking, vaping or dabbing cannabis can,
- be felt within seconds to minutes
- take up to 30 minutes to feel the full effects
- last up to six hours or longer
Effects from edible cannabis products can,

be felt as quickly as 30 minutes to two hours
take up to four hours to feel the full effects
last up to 12 hours
some residual effects can last up to 24 hours

The dangers of mixing cannabis with other substances

If you choose to consume cannabis in any form, avoid combining it with nicotine, alcohol, drugs, medications and other products, as it may negatively affect your health.

Mixing alcohol and cannabis increases impairment, which can lead to risky choices.

When cannabis is used with alcohol, it increases the strength of THC, which can lead to adverse side effects.
Simultaneous use of alcohol and cannabis is associated with increased intoxication and impairment.
Mixing cannabis and alcohol increases the risk of injury, falls or death.

Using cannabis can increase your rate of smoking tobacco, and vice versa. Using both cannabis and tobacco simultaneously can result in greater risk for addiction and health risks like cancer, cardiovascular and respiratory disease.

Mixing cannabis and medications may alter the effects of prescription and non-prescription drugs. Talk to your health care provider or pharmacist about ways to reduce your risks. Learn more about the effects of cannabis and medications.

Driving and cannabis use

Cannabis use alters the skills you need to drive, like quick thinking, decision-making, reaction time and concentration. Never drive impaired or get in a car with an impaired driver.

Plan a safe ride with a friend, use public transportation,  taxis or a ride-sharing service.

Learn more about impaired driving from the Ministry of Transportation. Learn more about the dangers of driving high from Health Canada.

Parenting, pregnancy and cannabis

Cannabis use in any form while pregnant and breastfeeding may have negative effects on both you and your baby. Learn more on our Substance use while pregnant and breastfeeding page.

Learn the risks of using cannabis while parenting, including unintentional cannabis poisoning in children.

For resources on how discuss cannabis use with your kids, visit our Parenting and Substance Use page.

Second hand cannabis smoke

For information on the health effects and strategies to reduce second hand cannabis smoke, visit our Second Hand Smoke page.

Home cultivation

Ontario Cannabis Legislation law allows people 19 and older to grow up to four cannabis plants per home (not four per person). Seeds can be bought legally from the Ontario Cannabis Store.

If you grow at home, you must follow building and fire codes and the Residential Tenancies Act. Unsafe equipment, high-power lights, or home-made wiring can raise fire and electrical risks.

Home growing can cause strong smells, especially when plants flower or when cannabis is dried and processed. Smells are not known to cause health problems, but they can still bother neighbours.

Growing indoors can also raise humidity, which can lead to mould if moisture is not controlled. Region of Waterloo Public Health does not conduct mould testing. To arrange for testing, contact a private air quality company. For mould in a rental unit, contact your municipality's by-law or property standards office.

It is not recommended that you process cannabis concentrates at home.

Keep plants and cannabis products locked up and out of reach of children and pets to prevent accidental poisoning.

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