Studies Examining Marijuana and COPD
Joan Vos MacDonald
Joan Vos MacDonald is a freelance writer living in upstate New York.
Whether marijuana use increases COPD susceptibility remains uncertain.
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.
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.
Whether marijuana use increases COPD susceptibility remains uncertain.
Marijuana and COPD: Is There a Connection?
Chronic obstructive pulmonary disease (COPD) is connected to breathing irritants. For this reason, researchers have been curious about a link between COPD and smoking marijuana.
Marijuana use is not uncommon. A national survey in 2017 showed that 45 percent of high school seniors reported using marijuana in their lifetime. About 6 percent said they used it on a daily basis, while reported daily use of tobacco was just 4.2 percent.
Use among adults is growing as well. A 2015 report noted that marijuana use doubled among U.S. adults over a 10-year span. In 2018, researchers found that the greatest increase in marijuana use since 2000 has been among adults age 50 and older.
COPD is an umbrella term that describes chronic lung conditions such as emphysema, chronic bronchitis, and nonreversible asthma-like symptoms. It’s a common condition in people who have a history of smoking.
In fact, it’s estimated that 90 percent of people with COPD have smoked or currently smoke. In the United States, about 30 million people have COPD, and half of them don’t know.
So could smoking marijuana increase your risk of COPD? Read on to learn what researchers have found about marijuana use and lung health.
Marijuana smoke contains many of the same chemicals as cigarette smoke. Marijuana also has a higher combustion rate, or burn rate. The short-term effect of smoking marijuana may depend on the dose.
However, repeated and consistent use of marijuana may increase the risk of poor respiratory health. Smoking marijuana long-term can:
- increase coughing episodes
- increase mucus production
- damage mucus membranes
- increase risk of lung infections
But it’s the habits that may play the largest role in overall lung health. People often smoke marijuana differently than they smoke cigarettes. For example, they may hold smoke longer and deeper into the lungs and smoke to a shorter butt length.
Holding in the smoke affects the amount of tar the lungs retain. Compared to smoking tobacco, a 2014 review of studies shows that marijuana inhalation techniques cause four times more tar to be inhaled. A third more tar gets into the lower airways.
Longer and deeper inhalations also increase the carboxyhemoglobin concentration in your blood by five times. Carboxyhemoglobin is created when carbon monoxide bonds with the hemoglobin in your blood.
When you smoke, you inhale carbon monoxide. It’s more likely to bind to hemoglobin than oxygen is. As a result, your hemoglobin carries more carbon monoxide and less oxygen through your blood.
There is significant interest in studying marijuana. Scientists want to learn about its medical and relaxation purposes as well as its direct relationship to lung issues like COPD. But there are many legal, social, and practical limitations.
Factors that impact research and results include:
Marijuana is a Schedule 1 drug. This means the U.S. Food and Drug Administration doesn’t consider the drug to have a medical purpose. Schedule 1 drugs are classified this way because they’re thought to have a high chance of abuse.
Marijuana’s classification makes studying its use expensive and time-consuming.
The amount of THC and other chemicals in marijuana can change based on the strain. The chemicals inhaled can also change based on the size of the cigarette or how much smoke is inhaled. Controlling for quality and comparing across studies can be difficult.
It’s difficult to keep track of how much of the active ingredients are consumed. The average person can’t identify the dose they’ve smoked. Most studies also focus on frequency of use but ignore other details that may affect health and a study’s results.
These factors include:
- joint size
- intensity of how someone smokes a joint
- whether people share joints
- use of a water pipe or vaporizer
Even though research is limited for marijuana, smoking anything can be unhealthy for your lungs. Most COPD symptoms aren’t noticeable until the condition has progressed and a certain amount of lung damage has occurred.
Still, keep an eye out for the following symptoms:
- shortness of breath
- chronic cough
- chest tightness
- frequent colds and other respiratory infections
More serious symptoms of COPD go along with more severe lung damage. They include:
- swelling in your feet, legs, and hands
- extreme weight loss
- inability to catch your breath
- blue fingernails or lips
Call your doctor right away if you experience any of these symptoms, especially if you have a history of smoking.
Marijuana smoke has many of the same chemicals as tobacco, but the link between marijuana use and COPD is not as clear. Learn what research says.