Cannabis and tobacco use

There are many studies that report on the harmful health effects of smoking tobacco, such as cancer, respiratory disease (bronchitis, emphysema and asthma) and heart disease. While there have been few studies conducted on the effects of cannabis smoke, there is growing evidence that there are similar major health concerns for those who smoke cannabis.

Tobacco and cannabis smoke both contain harmful chemicals, including carcinogens which are absorbed when inhaled. This exposes the smoker's lungs to greater risks of developing major respiratory diseases and/or cancer.

What are the links between smoking tobacco and cannabis?

International studies have found specific links between smoking both tobacco and cannabis,
such as:

  • many people who try cannabis have previously smoked tobacco
  • many current cannabis smokers are also current tobacco smokers
  • early onset of tobacco use may act as a gateway to future cannabis use
  • nicotine dependence can develop if tobacco is used in combination with cannabis
  • smoking both cannabis and tobacco increases health risks over and above smoking either drug alone

Are there any differences in smoking cannabis versus tobacco?

Tobacco is usually smoked in tailor-made or roll your own cigarettes, while cannabis is smoked in a variety of ways, such as:

  • a pipe with/without tobacco
  • a roll your own cigarette (or joint ) with a long cardboard tip, with/without tobacco
  • a bong (water pipe) or bucket bong with/without tobacco

The most harmful way of smoking cannabis is through a bong or bucket bong*. Inhaling smoke through water makes it cooler, which makes it easier for the smoker to inhale a greater volume of smoke more deeply into the lungs. This increases the surface area for tar and other carcinogens to affect the respiratory system. Around two-thirds of Australian cannabis smokers mix tobacco, with their cannabis. The combination of these two substances increases exposure to harmful chemicals, causing greater risks to the lungs, respiratory organs as well as the cardiovascular system.

Compared to tobacco cigarette smokers, people who smoke cannabis typically:

  • inhale more smoke (two-thirds larger puff volume)
  • inhale the smoke deeper into the lungs (one-third greater depth of inhalation)
  • hold the smoke in the lungs for longer time periods (up to four times longer)

This results in the lungs being exposed to:

  • greater amounts of carbon monoxide and other smoke irritants
  • greater retention of tar in the respiratory tract

Both carbon monoxide and tar increase the risks of a range of health problems including respiratory tract infections, bronchitis and lung cancer.

* A large bottle with the bottom cut off is inserted into a bucket of water. Once the cannabis/tobacco is heated, the bottle fills with smoke which is then forced from the bottle with downward pressure and inhaled into the lungs via the mouth peice.

Factsheet published June 1, 2008. Updated October 1, 2011.