Daily Inhaled Cannabis Linked to Higher Asthma and COPD Risk: Study
USA: New research has revealed that daily inhaled cannabis use was associated with a significantly increased risk of asthma and COPD, even among adults who had never smoked tobacco. Adjusted analyses confirmed that frequent cannabis inhalation over 30 days raised the likelihood of these respiratory conditions.
A large cross-sectional study published in the Journal of General Internal Medicine has added fresh evidence to growing concerns about the respiratory impact of cannabis smoke.
Conducted by Alison S. Rustagi and colleagues from the Center for Data to Discovery and Delivery Innovation (3DI), San Francisco VA Health Care System, the study evaluated data from 379,049 adults participating in the U.S. Behavioral Risk Factor Surveillance System (BRFSS) surveys between 2016 and 2020.
The research aimed to determine whether inhaled cannabis was independently associated with asthma and chronic obstructive pulmonary disease (COPD), separate from the well-established effects of tobacco smoking.
Participants, aged 18 to 74 years, reported their cannabis use over the past 30 days, ranging from none to daily use. The investigators then assessed whether these exposure levels correlated with self-reported medical diagnoses of asthma or COPD, adjusting for demographic variables and tobacco use history.
The analysis revealed the following findings:
- A total of 23,035 adults in the cohort reported using inhaled cannabis.
- Cannabis inhalation was associated with higher odds of respiratory disease.
- Daily cannabis users had a 44% higher likelihood of asthma (aOR 1.44).
- This association persisted among lifelong non-smokers, with an aOR of 1.51.
- Cannabis inhalation was also linked to increased odds of COPD in the overall population (aOR 1.27).
- However, the COPD association was not statistically significant among individuals who had never smoked tobacco.
The findings suggest a potential dose–response pattern, with risk increasing alongside the frequency of cannabis use. This pattern strengthens the biological plausibility of the association and supports earlier studies pointing to airway inflammation, structural lung changes, and other early signs of chronic pulmonary impairment among regular cannabis users.
The authors noted key limitations, including the cross-sectional design, which prevents establishing whether cannabis use occurred before the onset of asthma or COPD. Both exposure and disease status were self-reported, posing a risk of misreporting. The study also lacked data on lifetime cannabis use and other lung disease risk factors. However, the researchers added that cannabis use is typically reported accurately in surveys, particularly in states where it is legal.
Despite these limitations, the study leverages one of the largest nationally representative datasets available, offering timely insights as millions of Americans continue to take up cannabis each year. The authors stress that clinicians should routinely ask patients with asthma or COPD about cannabis use and counsel them that inhaled cannabis cannot be considered safe for respiratory health.
"The findings highlight the need for more robust longitudinal research to clarify whether cannabis inhalation directly contributes to the development of chronic lung disease and to what extent it represents a modifiable risk factor," the authors concluded.
Reference:
Rustagi, A.S., Jeffers, A.M., Graham, F.J. et al. Inhaled Cannabis, Asthma, and Chronic Obstructive Pulmonary Disease: A Population-Based Cross-Sectional Study of n = 379,049. J GEN INTERN MED (2025). https://doi.org/10.1007/s11606-025-09833-8
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