Risks associated with methods of cannabis use

Every method of cannabis use carries its own health risks. This page presents the known risks for the following methods:

• Smoking
• Inhaling by vaporization
• Vaping
• Ingesting edible products
• Using topical cannabis products

The risks associated with the use of substances such as cannabis can be explained by the law of effect. Since each person uses cannabis at different frequencies, reacts differently and since the THC concentration varies depending on the product, it is difficult to predict with certainty the intensity and duration of the effects and the possible side effects.

In general, frequent, intense and long-term cannabis use increases the health risks. Using products with a high THC content is also known to increase the risks associated with mental health and cognitive abilities.

If you are using or would like to use cannabis, visit the Lower-risk cannabis use page. It contains information that will help you make informed choices to reduce the risks that using this substance may have for you and people around you.

It is mainly the dried flowers, resin and some extracts of cannabis that can be smoked. As with tobacco, cannabis smoke irritates the airway and can cause severe coughing spells. Smoke from cannabis products contains toxins similar to those found in tobacco. It can promote the development of lung diseases, such as chronic bronchitis.

Some pipes (bongs) have a water reservoir that the smoke enters before it is inhaled. Some users believe that the water filters the toxins in the smoke, which has not been proven. The water cools the smoke and gives it a smoother feel. However, it does not reduce the risks associated with this method of use.

At this time, very little information is available on the health risks of secondhand cannabis smoke. Several questions remain unanswered. As a precaution, since the composition of secondhand smoke is similar to that of tobacco, avoid exposing people around you to secondhand cannabis smoke. See the section Protect your lungs and those of people around you, which provides tips on how to reduce the risks associated with smoking cannabis.

“Vaporization” means that the dried cannabis or a cannabis extract is heated to a temperature below the combustion temperature of the product. Inhaling aerosols produced by vaporizing cannabis is mainly done with the dried flowers and some forms of extracts of cannabis. An aerosol containing the active ingredients is produced and inhaled. Since the cannabis is heated to a temperature below the combustion point, fewer toxic by-products are released into the aerosol compared with combustion of the product when smoked.

Some people vaporize the dried flowers or concentrated cannabis extracts at high temperatures using a technique known as dabbing. The high vaporization temperature releases harmful substances to lung health, leading sometimes to serious lung diseases.

The main cannabis extracts used for dabbing contain a very high concentration of THC. Rapid vaporization of cannabis can lead to the full dose of THC being consumed in a short period of time or even in a single inhalation. This practice can lead to overdose or unpleasant side effects such as anxiety, paranoia, disorientation, nausea and vomiting.

Dabbing is likely to increase the risk of developing cannabis tolerance and dependence, since it involves inhaling high doses of THC in a short period of time. People who use concentrated cannabis extracts report more symptoms of cannabis use disorder, dependence and withdrawal than people who use other forms.

The term vaping is sometimes used to encompass both dabbing and vaporizing, but vaping is a different method of use.

The known risks of vaping cannabis are mainly related to the THC concentration and the possibility of developing a vaping-associated lung illness .

Vaping products often contain a high concentration of THC. This means they can cause severe side effects and increase the risk of developing dependence or a mental health disorder. Vaping is also associated with a risk of developing a severe pulmonary disease. The exact cause of this risk is not yet known. For more information, see the warning against vaping cannabis  (in French only) on the website of the Ministère de la Santé et des Services sociaux.

Little is known about the other risks associated with vaping cannabis. For instance, they are associated with accidental ingestion by youths. Like any substance or electronic device, there are risks associated with handling vaping products. Electronic vaping device also pose risks of malfunctions, that can result in inappropriate vaporization heat and harm to the person vaping, particularly if it explodes.

Ingesting cannabis mainly refers to edible products, such as oils, nanoemulsions, i.e., extracts that dissolve in water, food and beverages. Unlike the effects of smoking cannabis, which are felt within minutes of inhaling, it can take 30 to 60 minutes or even longer to feel the effects of edible products. 
A person who does not feel the effects may be tempted to take another dose, resulting in an intoxication. In cases of intoxication, which can vary in intensity, the person may experience anxiety, paranoia, disorientation, nausea, vomiting, and even loss of consciousness.

Edible cannabis products can look and taste the same as conventional food products, which can lead to accidental ingestion. Children are particularly at risk in these situations.

See the tips on consuming edible cannabis products to avoid adverse effects.
 

Little is known about the risks associated with using topical cannabis products, for example on the skin, nails or hair. Very little information is available on this method of use.

The most likely risk is unintentional ingestion by children, which can lead to overdose and hospitalization. An ingredient in the product used may also cause an irritating or allergic skin reaction.