Health Effects of Cannabis
THC and CBD
Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are two of the hundreds of chemicals found in cannabis.
THC causes the “high” feeling. CBD has little or no effect on the brain and can even decrease the “high” feeling.
To help reduce the effects of THC, choose products with more CBD than THC.
The Effects of Cannabis
Cannabis does not have the same effect on everyone. Some people feel relaxed, talkative, giggly, or have stronger sensations; others feel anxious, restless, have difficulty thinking, poor memory, become fearful or confused.
Risk of severe or long-term cannabis related health problems are higher if you:
- use cannabis with high THC content (10% or higher for dried cannabis, 2.5mg or higher for edibles),
- use daily or almost daily, and
- start using at 25 years of age or younger.
Cannabis use is linked to dependency, mental illness, reproductive issues, memory and concentration problems and issues with decision making. Smoking cannabis can cause lung problems; such as bronchitis, infections, chronic cough, and mucus build up in the throat.
Reducing harms and use of cannabis
Start with a product that is lower in THC (10% or less for dried cannabis and 2.5mg or less for edibles). Go slowly by starting with a small amount, and wait to feel the effects before taking more.
Always label cannabis products, and store in child-resistant packaging out of sight and reach of those who should not be consuming it. Find more information on how to protect your children from alcohol, drugs, and poisonings on our home safety page.
Cannabis can have risks for anyone. If you choose to use cannabis, take the following steps to reduce risks to your health:
Delay using cannabis until mid 20’s or older.
Choose cannabis with high CBD and 10% THC or lower.
Choose natural cannabis over synthetic cannabinoids. An example of a synthetic cannabinoid is "K2" or "Spice".
Edibles are safer on your lung health but there is the risk of taking too much, because the effects take 30min to 2 hours to kick in.
Vaping cannabis may reduce some health risks, but vaping is not risk-free. The long-term health effects are still unknown.
If you smoke cannabis, avoid “inhaling deeply” or “breath-holding”.
Limit cannabis use to weekends or one day a week at most.
Don’t use cannabis and drive or operate machinery.
Avoid cannabis if you are at risk for mental illness, planning a pregnancy, pregnant or breastfeeding. The Society of Obstetricians and Gynaecologists of Canada has more information on pregnancy and substance use.
Check out Canada’s Lower-Risk Cannabis Use Guidelines to learn more about how you can reduce your risk of experiencing harms.
Is cannabis addictive?
People who use cannabis daily or near daily can develop a psychological or physical dependence on it. Five to nine per cent of people who have used cannabis in their lifetime will become dependent on it. The risk of dependence increases to 17 per cent among those who start using cannabis in their youth.
People who frequently use cannabis then stop using it may develop withdrawal symptoms such as:
- feeling irritable,
- mood and sleep problems,
- decreased appetite,
- cravings,
- restlessness, and
- physical discomforts such as stomach pain, sweating, and headaches.
For help with cutting back or stopping your cannabis use, visit KFL&A Public Health's Getting Help page for local support options.
Resources
- Canada's Lower-Risk Cannabis Use Guidelines (français)(PDF) - CAMH
- Knowing Your Limits with Cannabis (PDF) - Canadian Centre on Substance Use and Addiction
- COVID-19 and Cannabis Use
- COVID-19 and Cannabis Smoking: 4 Things You Should Know
- Things to know about cannabis (français)
- Cannabis and Cancer (français) (PDF) - Ontario Health, Cancer Care Ontario
- A guide to cannabis for older adults (PDF) - Canadian Centre on Substance Use and Addiction
- Cannabis, Tobacco, and Vape Laws - KFL&A Public health
- Know the Law (français) - KFL&A Public Community Partnership