WEDNESDAY, Feb. 21, 2007 (HealthDay News) -- People who smoke marijuana for a long time face many of the same kinds of respiratory problems -- such as phlegm, coughing and wheezing -- as long-term cigarette smokers, say researchers at the Yale School of Medicine.
They reviewed previous studies from 1966 to 2005 that examined the association between marijuana and pulmonary function and respiratory complications. Some of the studies found a link between short-term marijuana use and relaxation and opening of the air passages.
However, other studies identified an association between long-term marijuana use and increased risk of respiratory symptoms, suggestive of obstructive lung disease. The data did not show an association between long-term marijuana smoking and airflow obstruction (emphysema), the Yale researchers said.
Their study is published in the current issue of the journal Archives of Internal Medicine.
There were several common kinds of limitations in the studies they reviewed, the Yale researchers noted. These included: 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," study first author Dr. Jeanette M. Tetrault, ambulatory care fellow at Yale School of Medicine and the Department of Veterans Affairs Connecticut Healthcare System, said in a prepared statement.
More information
The American Academy of Family Physicians has more about the dangers of marijuana.
