Marijuana Smokers Have More Respiratory Symptoms

July 3, 2018

By Reuters Staff 

NEW YORK—Marijuana smoking increases the risk of cough, sputum production, and wheezing, according to a systematic review and meta-analysis.

Marijuana cigarettes contain particulate matter, toxic gases, reactive oxygen species, and polycyclic aromatic hydrocarbons at concentrations much higher than that in tobacco smoke, and studies have found marijuana to be associated with bronchial inflammation similar to that seen with smoking tobacco.

Dr. Mehrnaz Ghasemiesfe from University of California, San Francisco and San Francisco Veterans Affairs Medical Center and colleagues examined whether marijuana use is associated with respiratory symptoms, obstructive lung disease, and changes in pulmonary function in their systematic review and meta-analysis of 22 studies (10 prospective cohort and 12 cross-sectional).

Overall, 1255 individuals had more than 10 joint-years of exposure, and 756 marijuana-only smokers had more than 20 joint-years of exposure.

Low-strength evidence from the observational studies suggested a 2.04-fold increased risk of cough, 3.84-fold increased risk of sputum production, and 55% increased risk of wheezing among marijuana smokers, compared with non-smokers, according to the report online July 2 in Annals of Internal Medicine.

Similar evidence from cross-sectional studies showed that marijuana use was associated with a 4.37-fold increased risk of cough, 3.40-fold increased risk of sputum production, 2.83-fold increased risk of wheezing, and 56% increased risk of dyspnea.

There was insufficient evidence to assess the possible link between daily marijuana use and changes in pulmonary function or development of obstructive lung disease.

"Given rapidly expanding use, we need large-scale longitudinal studies examining the long-term pulmonary effects of daily marijuana use," the researchers conclude.


Ann Intern Med 2018.

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