Surveying about 15,000 adolescents who reported regular use of e-cigarettes, cigarettes, or cannabis, researchers found that those vaping marijuana were about twice as likely to report respiratory symptoms like wheezing, compared to others who did not vape marijuana. Those who used the other substances or products did have some respiratory symptoms, mainly dry cough, but not to the degree of those using e-cig marijuana.
Potential Lung Injury
The type of symptoms reported with vaping marijuana are more indicative of future lung injury than occasional dry coughs or throat irritation, according to the study’s lead author, Carol Boyd, PhD, co-director of the Center for Study of Drugs, Alcohol, Smoking & Health at the University of Michigan School of Nursing. Those included:
Dry cough at night that is not associated with chest illness or infectionSleep disturbanceSounding wheezy during or after exerciseTalking limited by wheezingWheezing and whistling in the chest
Researchers expected that vaping nicotine would be the most strongly associated with problematic respiratory symptoms, Boyd says, so it was a surprise to see that vaping marijuana was worse. “This doesn’t mean vaping nicotine, or smoking either cigarettes or marijuana isn’t bad for you,” says Dr. Boyd. “Those do produce lung injury symptoms. But you may have worse symptoms if you’re vaping marijuana.” One limitation of the study, adds Dr. Boyd, is that it didn’t include using both cigarettes and vaped marijuana, so it might be possible that some of the symptoms are coming from that kind of combination.
Not Just Teens
Although the recent study focused only on those aged 12 to 17, previous research suggests this effect could be a problem for adults as well. A study in Nicotine & Tobacco Research looking at about 600 adults found that those who had vaped with marijuana within 12 months of the study period had significantly higher respiratory symptoms. Similar to the teen study, wheezing and whistling in the chest seemed the most prevalent issue, but participants also struggled with wheezing during or after exercise and dry coughing at night. “Compared to those who vaped nicotine, those who used marijuana in e-liquid form have a much higher association with respiratory problems,” says the lead author of that study, Zidian Xie, Ph.D., at the University of Rochester Medical Center. What remains to be seen, he adds, is whether these effects will linger over the long term. E-cigarettes, with or without marijuana, have only been on the market for about 10 years, which means the long-term association of vaping with marijuana is unknown. Unfortunately, says Dr. Xie, that also means it could get worse over time.
Potential Popcorn Lung
Although the recent study, and previous research, didn’t include possible causes for why vaping marijuana would possibly be more detrimental to lung health, one factor may be the connection to THC oil. Derived from cannabis, this oil is sometimes paired with vitamin E acetate to make it into a vaping product. The Centers for Disease Control and Prevention (CDC) reports that nearly 3,000 lung injuries—often called “popcorn lung”—have been caused by inhalation of the substance. The rate of these injuries is declining after state health departments sounded the alarm about it in late 2019, but the CDC is still cautioning people away from using THC-containing e-cigarettes. Even if a product doesn’t contain vitamin E acetate, it may contain other ingredients that are irritating to lung tissue, adds Dr. Boyd. More research is needed to look at what type of ingredients are having this effect, but for now, it’s important for parents and teens to know that vaping marijuana isn’t “safer” than e-cigs with nicotine or even regular cigarettes.
