Respiratory health effects of cannabis: Position Statement of The Thoracic Society of Australia and New Zealand


  • D. R. Taylor,

    1. Department of Medical and Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand,
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  • W. Hall

    1. National Drug and Alcohol Research Centre, University of New South Wales, Sydney, New South Wales and
    2. Office of Public Policy and Ethics, Institute of Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
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  • Funding: None

    Conflicts of interest: None

Correspondence to: D. Robin Taylor, Dunedin School of Medicine, PO Box 913, Dunedin, New Zealand. Email:



Both the gaseous and the particulate phases of tobacco and cannabis smoke contain a similar range of harmful chemicals. However, differing patterns of inhalation mean that smoking a ‘joint’ of cannabis results in exposure to significantly greater amounts of combusted material than with a tobacco cigarette. The histopathological effects of cannabis smoke exposure include changes consistent with acute and chronic bronchitis. Cellular dysplasia has also been observed, suggesting that, like tobacco smoke, cannabis exposure has the potential to cause malignancy. These features are consistent with the clinical presentation. Symptoms of cough and early morning sputum production are common (20−25%) even in young individuals who smoke cannabis alone. Almost all studies indicate that the effects of cannabis and tobacco smoking are additive and independent. Public health education should dispel the myth that cannabis smoking is relatively safe by highlighting that the adverse respiratory effects of smoking cannabis are similar to those of smoking tobacco, even although it remains to be confirmed that smoking cannabis alone leads to the development of chronic lung disease. (Intern Med J 2003; 33: 310−313)