Cannabis Smoke Affects Lungs Similarly to Tobacco With Some Additional Risks | Research

The takeaway

A review found cannabis smoke causes symptoms similar to tobacco (cough, sputum, bronchitis) and may weaken immunity leading to pneumonia, with potential but inconclusive links to lung cancer with heavy, long-term use.

Read this if you smoke cannabis and want to understand the effects on your lungs.

Cannabis smoke causes bronchitis symptoms, immune suppression, and potential but inconclusive lung cancer risk.

What the researchers found

This review examined the pulmonary effects of cannabis smoking. Cannabis smoke affects the lungs similarly to tobacco smoke, producing symptoms of increased cough, sputum production, and airway hyperinflation.

With increasing years of use, cannabis can cause serious lung diseases. It can weaken the immune system in the lungs, leading to pneumonia. Regular use has been linked to symptoms of chronic bronchitis, and heavy long-term use on its own may cause airway obstruction.

Based on immunohistopathological and epidemiological evidence, the review concluded that cannabis poses a potential risk for lung cancer. However, the association was described as "not decisive," meaning the evidence was suggestive but not conclusive. The difficulty in separating cannabis effects from tobacco effects (since many users smoke both) was noted as a major methodological challenge.

Why it matters

As cannabis use increases with legalization, understanding its respiratory effects independent of tobacco is important. This review provides a concise summary of the lung-related risks, which include bronchitis, immune suppression, airway obstruction, and a potential but unproven cancer risk.

The numbers in context

The review synthesized evidence from immunohistopathological and epidemiological studies. Specific rates were not quantified, but associations were described for bronchitis, pneumonia, airway obstruction, and potential lung cancer risk.

How the study worked

Narrative review examining immunohistopathological and epidemiological evidence on the respiratory effects of cannabis smoking, published as a chapter in Advances in Experimental Medicine and Biology.

What this study cannot tell us

Brief review format limits depth. Does not systematically weigh conflicting evidence (some large studies found no cancer link). Cannot fully separate cannabis effects from tobacco effects. Does not address dose-response relationships or the effects of vaporization versus smoking.

How to read the evidence

Moderate evidence from a narrative review synthesizing immunohistopathological and epidemiological data, though the review is brief and does not systematically assess evidence quality.

When this study was published

Published in 2016. Respiratory effects of cannabis continue to be studied as use patterns and product types evolve.

The bigger picture

The respiratory effects of cannabis remain one of the most debated areas of cannabis research. While some studies show increased lung capacity (paradoxically), this review emphasizes the harmful effects: bronchitis, infection vulnerability, and potential cancer risk. Non-combustion methods (vaporization, edibles) could mitigate these risks.

Questions still open

Do the respiratory risks of cannabis smoking outweigh the medical benefits for patients who could use non-combustion alternatives? Would long-term prospective studies of cannabis-only smokers clarify the cancer risk? How do modern high-potency products affect respiratory risk?

Common questions

Does smoking cannabis damage your lungs?

Yes. This review found cannabis smoke causes bronchitis symptoms, can weaken lung immunity leading to pneumonia, and may cause airway obstruction with heavy long-term use. The cancer risk is possible but not proven conclusively.

Is cannabis smoke as harmful as tobacco smoke?

Cannabis smoke produces many of the same harmful effects on the lungs (bronchitis, cough, sputum). However, some large studies have not found the same degree of lung function decline as with tobacco. The cancer risk from cannabis is still debated, while tobacco's cancer risk is firmly established.

Read the original research

Damaging Effects of Cannabis Use on the Lungs.

Advances in experimental medicine and biology, 952, 31-34

View on PubMed ↗

Citation

Yayan, Josef; Rasche, Kurt. (2016). Damaging Effects of Cannabis Use on the Lungs.. Advances in experimental medicine and biology, 952, 31-34.