As cannabis becomes more widely legalized and socially accepted, many people see it as a safer alternative to tobacco.
But new research suggests that inhaling cannabis—whether by smoking, vaping, or dabbing—may pose serious risks to lung health, including a significantly higher chance of developing asthma.
A study published in the Journal of General Internal Medicine by researchers at UC San Francisco examined the link between cannabis use and respiratory disease.
They found that people who inhaled marijuana daily had a 44% greater risk of developing asthma.
The same group also showed a 27% higher risk of chronic obstructive pulmonary disease (COPD), though the researchers noted that the true risk may be even greater because COPD takes decades to develop.
The study defined inhaling as any method that brings cannabis smoke or vapor into the lungs. This included traditional smoking, electronic vaping, and dabbing, which involves inhaling concentrated marijuana vapors.
Importantly, the elevated risks were observed even among people who had never smoked cigarettes.
For non-smokers of tobacco, the findings were particularly concerning. In this group, inhaling cannabis daily was linked to a 51% greater likelihood of developing asthma.
While the increase in COPD risk for this group was not statistically significant, the trend still pointed to potential long-term harm.
The study is the largest to date that looks specifically at cannabis inhalation and lung health in people with no history of tobacco use.
It analyzed data from nearly 380,000 U.S. adults who participated in the Behavioral Risk Factor Surveillance System, a survey run by the Centers for Disease Control and Prevention (CDC).
Of those participants, about 222,000 reported that they had never smoked cigarettes, providing researchers with a clear picture of cannabis’s effects independent of tobacco.
Experts caution that the growing perception of cannabis as harmless may be misleading. While decades of research and public health campaigns have firmly established tobacco smoking as dangerous, cannabis has not been studied as extensively.
With legalization spreading across much of the United States, researchers worry that many people underestimate the potential risks to their lungs.
“The message about smoking tobacco being bad for you has gotten out there, but for cannabis, it’s much less clear,” said Dr. Alison Rustagi, the study’s lead author and an assistant professor at UCSF.
“If people are looking to reduce their likelihood of developing a chronic lung disease, they should not start using cannabis. And if they already smoke cannabis, they should do it less often.”
The study does not suggest that all cannabis use is equally harmful, but it highlights the dangers of daily inhalation.
Just as with tobacco, experts say moderation—or avoidance altogether—may be the key to protecting long-term lung health.
