Canadian Cancer Society logo
You are here: 

Smoking marijuana

Marijuana is not really a form of tobacco. Marijuana comes from the cannabis plant. Other forms of cannabis include sinsemilla, hashish and cannabis oil. The way marijuana and other forms of cannabis are used may mean that they have similar risks to tobacco products.

The main psychoactive ingredient in marijuana is THC (delta-9-tetrahydrocannabinol). THC is a type of cannabinoid. There are many other types of cannabinoids in marijuana. Cannabinoids are chemicals that act on certain receptors on cells in our body, especially cells in the central nervous systemcentral nervous systemThe brain and spinal cord, which work together to control all the functions of the body..

Marijuana smoke and your health

People who smoke marijuana tend to inhale more smoke per puff and hold it in their lungs for as much as 4 times longer than people who smoke tobacco cigarettes. This means that smoking 2–3 marijuana cigarettes can expose you to roughly the same amount of smoke as 20 tobacco cigarettes.

Marijuana users and people exposed to second-hand marijuana smoke may have many of the same health problems as people exposed to cigarette smoke, including an increased risk of cancer.

Marijuana and cancer risk

Current evidence suggests that smoking marijuana for a long period of time may increase your risk of head, neck, lung and throat cancers. However, the quality of this research is not as strong or comprehensive as the evidence that links tobacco use and cancer. Many people who smoke marijuana also smoke tobacco or mix the marijuana with tobacco. This makes it hard to know how strong the link between smoking marijuana and cancer is. Also, there is no standard amount of THC in each marijuana cigarette, so it is difficult to compare results across different studies.

Smoking marijuana may increase cancer risk because marijuana smoke contains many of the same cancer-causing substances (carcinogens) as tobacco smoke. Some research has shown that smoking marijuana may be linked to changes in some of the cells in the body, including precancerous changes in the lung cells.

More research is needed to better understand the cancer risks associated with long-term recreational smoking of marijuana and of exposure to second-hand marijuana smoke.

Medical marijuana

Marijuana is an illegal substance in Canada. The Canadian government allows seriously ill people access to marijuana for medical reasons. This is called medical marijuana.

Some people believe that marijuana can help control or relieve some of the symptoms of cancer or the side effects of cancer treatments. But research studies done so far do not give a clear answer about the effectiveness of smoking marijuana. Research does show that some cannabinoids can help with some symptoms and side effects, and drugs containing cannabinoids have been developed to treat nausea and vomiting or pain. Find out more about medical marijuana and cannabinoids.


Donna Blundon It is funny how one of the darkest times in your life can be one of the best times in your life, and it was all because of Daffodil Place.

Read Donna's story

Support from someone who has ‘been there’

Illustration of conversation

The Canadian Cancer Society’s peer support program is a telephone support service that matches cancer patients and their caregivers with specially trained volunteers.

Learn more