Pulmonary Effects of Marijuana Inhalation

Megan L Howden; Matthew T Naughton


Expert Rev Resp Med. 2011;5(1):87-92. 

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Expert Commentary

In summary, marijuana is commonly used in our society. Unfortunately, accurate data about the health effects of smoking marijuana can be difficult to accurately collect in part due to its illegal nature but also due to variable techniques of smoking and the frequent confounding factor of tobacco smoking. Despite this, the evidence suggests that regular cannabis smoking is associated with a modest impairment in lung function, consisting mainly of a slight increase in airway resistance and hyperinflation. While the clinical significance of these changes is not clear, there is certainly an association of marijuana smoking with respiratory symptoms. The findings of large airway edema and inflammation could correlate with the observed lung function impairment and symptomatology. Numerous case reports also raise the possibility of marijuana causing significant bullous disease in relatively young subjects, though stronger evidence is not available to confirm these findings, and thus conclusions cannot be confidently drawn. Normal spirometry cannot exclude significant lung disease associated with marijuana use. In addition, some studies have suggested an association with lung cancer and certainly marijuana can lead to histological changes in the airways similar to those of tobacco smokers. Other studies, however, have found no association between marijuana smoking and malignancy. Finally, increased healthcare utilization and a potential for impaired lung defences makes cannabis smoking a significant health concern from a respiratory perspective.


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