Long-Term Marijuana Smoking Leads To Respiratory Complaints

Long-term exposure to marijuana smoke is linked to many of the same health problems as tobacco smoke, such as increased respiratory symptoms like cough, phlegm and wheeze, according to a new study by researchers at Yale School of Medicine.

Marijuana is the most widely used illicit drug in the United States, and abuse of the drug is on the rise. The study is published in Archives of Internal Medicine. First author Jeanette M. Tetrault, M.D., and colleagues sought to find the relationship between marijuana smoking and pulmonary function or respiratory complications.

"While there is convincing data on the effects of tobacco smoke on pulmonary clinical outcomes, the effect of marijuana smoke has been poorly understood," said Tetrault, ambulatory care fellow at Yale School of Medicine and the Department of Veterans Affairs Connecticut Healthcare System.

Tetrault and colleagues systematically reviewed articles from 1966 through 2005 identified from the MEDLINE, PsychINFO and EMBASE databases that evaluated the effect of marijuana smoking on pulmonary function and respiratory complications. Of the 34 articles that met selection criteria, 12 were classified as challenge studies because they examined the link between short-term marijuana use and airway response. Eleven of the 12 studies found an association between short-term marijuana use and relaxation and opening of the air passages.

The study's physiologic data failed to show an association between long-term marijuana smoking and airflow obstruction (emphysema). However, all 14 studies that assessed long-term marijuana smoking and respiratory complications noted an association with increased respiratory symptoms, suggesting obstructive lung disease.

The authors noted several common limitations among the studies, including inadequate control of the complicating effect of tobacco smoking; lack of standardized measures for the amount or duration of marijuana use; and lack of standardized measures of the outcomes that were evaluated.

"Despite these limitations, clinicians should advise their patients of the potential negative impact of marijuana smoking on overall lung health," said Tetrault.

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Other authors on the study included Kristina Crothers, M.D., Brent A. Moore, Reena Mehra, M.D., John Concato, M.D., and David Fiellin, M.D.

Citation: Archives of Internal Medicine, Vol. 167, (February 12, 2007)

Contact: Karen N. Peart
Yale University