Marijuana Smoke Affects the Lungs Similarly to Tobacco but May Not Cause COPD | Research

The takeaway

Marijuana smoke causes increased cough and sputum production similar to tobacco, but the evidence does not show it contributes to chronic obstructive pulmonary disease, and its cancer risk remains unclear.

Read this if you smoke marijuana and want to understand its effects on your lungs.

No evidence that marijuana smoke causes COPD despite similar airway symptoms to tobacco

What the researchers found

The review found that marijuana smoke produces respiratory symptoms similar to tobacco: increased cough, sputum production, hyperinflation, and upper lobe emphysematous changes. However, at the time of publication, the evidence did not support a link between marijuana smoking and the development of COPD.

The cancer evidence was mixed. Some studies suggested marijuana smoke increases risk for head and neck squamous cell carcinoma, lung cancer, prostate cancer, and cervical cancer, while others found protective effects against malignancy. The carcinogenic effects remained unclear.

Marijuana smoke was shown to inhibit immune function, which has dual implications: it could impair defense against infection but also suggests therapeutic potential for autoimmune conditions. The authors noted that as legalization expands and alternative consumption methods (edibles, beverages) become common, most existing research on smoked marijuana may not apply to these newer products.

Why it matters

As marijuana legalization expands, understanding its respiratory effects is critical for public health guidance. The distinction between marijuana and tobacco in terms of COPD risk, and the unclear cancer evidence, complicates the messaging around marijuana smoking and health.

The numbers in context

Marijuana is the most commonly used drug of abuse in the US. The review covers effects on cough, sputum, hyperinflation, emphysema, COPD, multiple cancer types, and immune function.

How the study worked

This is a narrative review examining the respiratory tract effects of marijuana. The authors synthesized evidence from epidemiological studies, physiological research, and clinical observations covering pulmonary function, cancer risk, and immune effects.

What this study cannot tell us

This is a narrative review, not a systematic review, so study selection may be incomplete or biased. Most research examined whole marijuana smoke rather than THC or CBD specifically. Many studies had small sample sizes or inadequate controls for tobacco co-use. The research was conducted before widespread legalization changed use patterns.

How to read the evidence

This is a narrative review synthesizing a mixed body of evidence. Some included studies were well-designed, but others had significant limitations.

When this study was published

Published in 2014. Larger epidemiological studies on marijuana and lung disease have been published since, with ongoing debate.

The bigger picture

The respiratory effects of marijuana are a key public health question as legalization spreads. This review highlights an important nuance: while marijuana smoke shares many irritant properties with tobacco smoke, the overall disease trajectory may differ. The shift toward non-smoked cannabis products may eventually make this question less relevant.

Questions still open

Why does marijuana smoke appear not to cause COPD despite producing similar airway symptoms as tobacco? Do non-smoked cannabis products carry any respiratory risk? Would long-term studies with larger samples clarify the cancer question?

Common questions

Why might marijuana not cause COPD like tobacco does?

The reasons are not fully understood. Possible explanations include differences in smoking patterns (frequency, volume), anti-inflammatory properties of certain cannabinoids, or differences in the combustion products. Marijuana smokers typically inhale less total smoke over their lifetime than tobacco smokers.

Does switching to edibles eliminate respiratory risk?

Edibles bypass the lungs entirely, so they eliminate inhalation-related risks like cough, sputum, and any potential airway damage. However, the research reviewed here focused on smoked marijuana and may not apply to other forms.

Read the original research

Marijuana: respiratory tract effects.

Clinical reviews in allergy & immunology, 46(1), 65-81

View on PubMed ↗Publisher’s paper ↗

Citation

Owen, Kelly P; Sutter, Mark E; Albertson, Timothy E. (2014). Marijuana: respiratory tract effects.. Clinical reviews in allergy & immunology, 46(1), 65-81. https://doi.org/10.1007/s12016-013-8374-y