Studies Examining Marijuana and COPD

As more states legalize marijuana for medical and/or recreational use, people who have been diagnosed with chronic obstructive pulmonary disease (COPD) may wonder if marijuana use is safe or perhaps less harmful to their lung health than smoking tobacco. 

While it is estimated that 85% to 90% of COPD cases are caused by smoking cigarettes, studies report conflicting outcomes regarding marijuana use. In the meantime, The American Lung Association, the American Thoracic Society, and the National Institute on Drug Abuse caution the public, particularly those with respiratory problems, against smoking marijuana.

Although the risks of respiratory problems associated with marijuana may be lower than those associated with smoking tobacco, studies to date have shown that it is not risk free.

According to The American Lung Association, the danger has much to do with how marijuana is generally used, as it's often smoked using pipes, bongs or paper wrapped joints. Inhaling smoke is harmful to lung health, whether it is smoke from burning wood, tobacco, or marijuana. Toxins, irritants, and carcinogens are released when these materials combust, all of which can harm the lungs of those who smoke and those who inhale secondhand smoke. While marijuana smokers may inhale less smoke per day than cigarette smokers, they may inhale deeper and hold the smoke in longer, greatly increasing the amount of tar that remains in the lungs.

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According to the American Thoracic Society, regular marijuana smoking is likely to cause lung damage, which could potentially increase a person’s risk of developing COPD. A 2013 study showed that regularly smoking marijuana injures the cell linings of the lungs’ airways, which interferes with the ability to filter out germs and dust. 

Research has not yet concluded whether marijuana use affects the immune system, potentially depressing the body’s ability to fight disease. Marijuana use can make an already weakened immune system more vulnerable to respiratory problems associated with aspergillus, a fungus that grows on marijuana and which may be inhaled when marijuana is smoked. 

According to the National Institute of Drug Abuse, those who smoke marijuana regularly report more symptoms of chronic bronchitis than those who do not smoke. In younger smokers, marijuana smoking has also been associated with the development of large air sacs, called bullae. Ruptured bullae can leak air and potentially lead to a collapsed lung.

Pharmacists may want to urge patients who are considering marijuana use to discuss that use, and potential delivery systems, with their doctor, especially if they have COPD and/or other breathing problems.