COPD patients who smoked both cannabis and tobacco showed higher lung volumes and more bullous emphysema than tobacco-only smokers, suggesting cannabis adds a distinct pattern of lung damage.
Pulmonologists, COPD patients who smoke cannabis, primary care providers, and respiratory researchers
What the researchers found
Combined cannabis+tobacco smokers with COPD had significantly higher FVC (2.69 vs 2.33L), RV (4.09 vs 3.67L), TLC (7.13 vs 6.34L), and more bullous emphysema (17% vs 4%, p=0.02) compared to tobacco-only smokers.
Why it matters
Cannabis smoking's contribution to lung disease is poorly understood — this first-of-its-kind study in COPD patients reveals cannabis adds hyperinflation and bullous emphysema beyond tobacco's effects.
The numbers in context
199 COPD patients; combined smokers: FVC 2.69L vs 2.33L (p=0.001), RV 4.09L vs 3.67L (p=0.02), TLC 7.13L vs 6.34L (p=0.001); bullous emphysema 17% vs 4% (p=0.02); cannabis started ~4 years after tobacco.
How the study worked
Retrospective cross-sectional study at a safety-net hospital interviewing 199 COPD patients about smoking patterns and reviewing pulmonary function tests and chest imaging (2015-2020).
What this study cannot tell us
Retrospective design; self-reported cannabis use; safety-net hospital population may not generalize; no dose-response analysis; can't fully separate cannabis from tobacco effects.
How to read the evidence
First study of its kind in COPD patients with pulmonary function and imaging data, though retrospective and single-center.
When this study was published
Published in 2026 with 2015-2020 data, addressing a major gap in respiratory cannabis research.
The bigger picture
The hyperinflation pattern (higher volumes, more bullae) in combined smokers suggests cannabis may cause a distinct type of lung damage that compounds tobacco's effects differently than expected.
Questions still open
- Does the cannabis-specific bullous emphysema pattern increase pneumothorax risk? Would switching to non-smoked cannabis reduce lung damage progression in COPD patients?
Common questions
Does cannabis make COPD worse?
How is cannabis lung damage different from tobacco?
Read the original research
Impact of cannabis smoking in patients with COPD: A retrospective cross-sectional study in a safety- net hospital.
Heart & lung : the journal of critical care, 75, 263-269
Citation
Cherian, Sujith V; Karanth, Siddharth; Oldham, Sandra A; Estrada-Y-Martin, Rosa M. (2026). Impact of cannabis smoking in patients with COPD: A retrospective cross-sectional study in a safety- net hospital.. Heart & lung : the journal of critical care, 75, 263-269. https://doi.org/10.1016/j.hrtlng.2025.10.011
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