Is Cannabis Harmful to my Health?


Just as with other substances, using cannabis can harm your physical and mental health. Be informed about the effects of cannabis and how to protect yourself and the things that are important to you.

What is cannabis?
Cannabis, also known as pot, weed, or marijuana, comes from the dried flowering tops and leaves of the plant, Cannabis sativa or Cannabis indica. 


How can cannabis affect my physical health?
Using cannabis can have many short and long-term effects, including:

  • Coughing, wheezing, and shortness of breath (when smoked).
  • Lung infection or bronchitis (when smoked).
  • Low blood pressure (risk of fainting or passing out).
  • Increased heart rate (increased risk of heart attack).
  • Some forms of cancer.
  • Hyperemesis syndrome (uncontrollable vomiting).
  • Poor coordination and slow reaction time.
  • Increased risk of injury (e.g., motor vehicle collision, falls).

Is cannabis safer than tobacco?
Cannabis smoke has many similar carcinogens, toxins, and irritants to those found in tobacco smoke and known to cause cancer, heart disease and respiratory diseases like bronchitis. Cannabis is not harmless just because it’s more “natural”


How does cannabis affect my brain and mental health?
Cannabis use can have unwanted or unpleasant psychological effects such as:

  • Confusion, drowsiness, or trouble focusing.
  • Problems with memory and learning.
  • Addiction or Cannabis Use Disorder.
  • Depression, anxiety, fear or panic.
  • Psychotic episodes of paranoia, delusions, or hallucinations

How do I lower my risk of harm if I choose to use cannabis?

Choose low THC products (less than 10% or 2.5mg THC for edibles), use once per week or less, and do not drive after consuming. Delay use if you are under 25, and do not use if you are pregnant or breastfeeding

Is cannabis addictive?
Yes. Regular, daily, and heavy cannabis use can lead to dependence in the form of Cannabis Use Disorder. In fact, about 1 in 6 teenagers and 1 in 11 adults who use cannabis will develop an addiction. When someone stops consuming cannabis after regular or heavy consumption, they may experience withdrawal symptoms and feel the need to consume cannabis again to reduce symptoms (e.g., irritability, frustration, restlessness, trouble sleeping, depression or anxiety, cravings or changes in appetite, and weight loss).

Can you overdose on cannabis?
Yes. While cannabis overdose does not happen in the same way as opioids or other substances, there is still a risk of overconsumption which can cause high levels of anxiety, fear or panic, and psychotic episodes of paranoia, delusions or hallucinations. Hyperemesis syndrome involving uncontrollable vomiting may also occur.

When cannabis is purchased or received from an unregulated or “black market” source, the risk for overdose from other substances is also higher. Hidden substances such as opioids, cocaine, methamphetamine, MDMA, LSD, or household chemicals can be harmful and cause overdose from non-cannabis substances.

What do I need to know about cannabis edibles or extracts?

The effects of edibles are delayed, last longer, and can be more intense than inhaling cannabis. If you use edible cannabis, start small (2.5 mg of THC or less), and wait at least 4 hours before having more to avoid overconsuming and a bad reaction.


Urgent help
If unintentional ingestion or bad reaction, call 911 or the Ontario Poison Centre: 1-800-268-9017.
Windsor-Essex Crisis Line: 519-973-4435 (24/7 support)

Brief counselling and referrals to local support services
Connex Ontario: Telephone or Web Chat Service (24 hours/7 days a week) Addiction, Mental Health, and Problem Gambling Services
1-866-531-2600 |
Service available in English, French, and over 170 languages. All ages.

Kids Help Phone: Telephone or Web Chat Service (24 hours/7 days a week)
1-800-668-6868 |
Service available in English and French. Ages 29 and under.

Windsor-Essex County Health Unit Full list of treatment options in Windsor-Essex County.
On screen translation in 100+ languages.