Smoking Marijuana: Is It Safe for Someone with Mild COPD?

Smoking Marijuana and the Lungs

Dear Dr. Mahler: I live in Massachusetts where marijuana was legalized for recreational use this past November. What are your thoughts for smoking an occasional joint to “chill?” My primary care doctor has told me that I have mild COPD. I smoked cigarettes for about 20 years, but quit two years ago. I am currently taking Tudorza Pressair twice a day, and may use ProAir a few times a month. How safe is smoking marijuana for my lungs? Brian from Wooster, MA Dear Brian: Marijuana is the second most commonly smoked substance after tobacco.
Plant used for smoking marijuana

Marijuana plant

Although the harmful effects of tobacco smoke are well known, there is less information about the health effects of smoking marijuana. As most people know, marijuana can be inhaled in many ways – a joint, vaping, and water pipes – are the most common. It is impossible to predict if you will experience any lung damage from smoking an “occasional joint.” Here is some health information for you to consider. How can smoking marijuana damage my lungs? Smoke of any kind can cause bronchitis – inflammation and swelling of the breathing tubes. Marijuana smoke contains many of the same harmful chemicals as in tobacco smoke. We do not know if light users who smoke an amount equal to 1 – 2 joints a month over a long time may worsen your mild COPD. 
Smoking marijuana may cause a lung bullae

Arrows shows a lung bulla in the right upper lobe of the lung

There is evidence that smoking marijuana can cause large air sacs, called bullea, to develop in the lung. This is more likely to happen in younger marijuana smokers (less than 45 years of age). A bulla can cause someone to be short of breathe and may rupture or “pop.” Air leaking from a ruptured bulla can lead to a collapsed lung called a pneumothorax. For anyone with asthma or COPD, smoking marijuana can cause a “breathing attack.” What symptoms indicate that smoking marijuana is affecting my lungs? Like tobacco smoke, marijuana smoke can cause coughing, mucus, wheezing, shortness of breath, and swelling in the throat. Does smoking marijuana increase my risk of lung cancer? The answer is unclear, but it may increase the risk of lung cancer as marijuana smoke contains over 450 unique chemicals including those that can cause cancer (called carcinogens). Can marijuana increase my risk of a lung infection? Marijuana smokers can develop a lung infection from a mold called aspergillus. The mold, or fungus, lives on marijuana plants and is inhaled in smoke.  Has marijuana been used to treat some medical problems? Yes, marijuana has been used to treat many conditions including nausea and chronic pain. Several states allow health care providers to prescribe marijuana for health reasons. However, the Food and Drug Administration (FDA) has not approved marijuana for any medical condition. The FDA has approved medications that contain tetrahydrocannabinol (THC), the active ingredient in marijuana, for treatment of pain and nausea. In summary, smoke of any kind has the potential to damage your lungs, and is not recommended for anyone who has a lung condition. I hope that his information is helpful for you in making an informed decision. Sincerely, Donald A. Mahler, M.D.    

Donald A. Mahler, M.D. is Emeritus Professor of Medicine at Geisel School of Medicine at Dartmouth in Hanover, New Hampshire. He works as a pulmonary physician at Valley Regional Hospital in Claremont, NH, where he is Director of Respiratory Services.