Cannabis smoking may contribute to lung disease, pneumothorax, infections, and possibly lung cancer | Research

The takeaway

A review found emerging evidence that habitual cannabis smoking may contribute to COPD, pneumothorax, respiratory infections including tuberculosis, with biological plausibility for lung cancer risk.

Read this if you smoke cannabis and want to understand the lung health concerns.

Biological plausibility for lung cancer may precede epidemiological confirmation

What the researchers found

The review examined evidence on respiratory effects of cannabis smoking, noting that mental health concerns had dominated cannabis research while lung effects received relatively little attention.

The authors found emerging concern that habitual cannabis smoking may contribute to chronic obstructive pulmonary disease (COPD), pneumothorax (collapsed lung), and respiratory infections including tuberculosis.

Regarding lung cancer, the review noted that biological plausibility existed for an association (cannabis smoke contains carcinogens and causes cellular changes), even though epidemiological evidence had not yet definitively established the link. The authors suggested biological evidence may precede epidemiological confirmation.

The review emphasized that cannabis research was complicated by confounding from concurrent tobacco use and other social factors.

Why it matters

The review highlighted a gap between public perception of cannabis as safe and emerging evidence of respiratory harms, particularly relevant as cannabis smoking was widespread among young people.

The numbers in context

The review discussed qualitative evidence across multiple respiratory conditions but did not report pooled risk estimates.

How the study worked

Narrative review by chest physicians examining epidemiological and biological evidence for respiratory effects of cannabis smoking, published in the Journal of the Royal College of Physicians of Edinburgh.

What this study cannot tell us

Narrative review without systematic methodology. Many referenced studies were confounded by concurrent tobacco smoking. Epidemiological evidence for lung cancer specifically was acknowledged as incomplete.

How to read the evidence

Narrative review by clinical experts synthesizing emerging evidence, with acknowledged limitations in the underlying research.

When this study was published

Published in 2010. Research on cannabis and respiratory health has continued with larger studies since.

The bigger picture

This review represented the perspective of chest physicians concerned that respiratory effects of cannabis were being overlooked while mental health effects dominated the research agenda.

Questions still open

Will epidemiological studies eventually confirm the biological evidence for cannabis-related lung cancer? How much cannabis smoking is needed to meaningfully increase respiratory disease risk?

Common questions

Can smoking cannabis cause lung disease?

The review found emerging evidence linking habitual cannabis smoking to COPD, collapsed lung, and respiratory infections. The evidence was complicated by the fact that many cannabis smokers also smoke tobacco.

Does cannabis cause lung cancer?

At the time of this review, biological evidence suggested cannabis smoke contains carcinogens, but epidemiological studies had not definitively established a lung cancer link. The authors suggested biological evidence might precede epidemiological confirmation.

Read the original research

Cannabis and the lung.

The journal of the Royal College of Physicians of Edinburgh, 40(4), 328-3; quiz 333-4

View on PubMed ↗Publisher’s paper ↗

Citation

Reid, P T; Macleod, J; Robertson, J R. (2010). Cannabis and the lung.. The journal of the Royal College of Physicians of Edinburgh, 40(4), 328-3; quiz 333-4. https://doi.org/10.4997/JRCPE.2010.417