Systematic Review Links Smoked Marijuana to Lung Cancer Risk, Emphysema, COPD, and Multiple Respiratory Symptoms | Research

The takeaway

A systematic review of 48 studies found evidence linking smoked marijuana to lung cancer risk, bullous emphysema, COPD, and a range of respiratory symptoms including wheezing, cough, and phlegm production.

Read this if you smoke marijuana and want to understand the respiratory health risks.

48 studies link smoked marijuana to lung cancer risk, emphysema, and COPD

What the researchers found

This systematic review compiled 48 studies on the respiratory effects of smoking marijuana. The findings were organized by condition category.

For lung cancer, the evidence indicated risk from inhalational marijuana, though the relationship was complicated by concurrent tobacco use in many studies. For emphysema and COPD, an association with marijuana smoking was found, including cases of bullous emphysema and spontaneous pneumothorax.

A wide range of respiratory symptoms were reported by marijuana smokers: wheezing, shortness of breath, altered pulmonary function tests, cough, phlegm production, and bronchodilation. The bronchodilation finding is notable as a potential short-term benefit that contrasts with long-term risks.

Why it matters

As marijuana use increases with legalization, understanding respiratory risks becomes more important. This review provides the most comprehensive compilation of evidence on smoked marijuana's effects on the lungs, helping users make informed decisions about consumption methods.

The numbers in context

48 articles reviewed. Primary categories: lung cancer, bullous emphysema/COPD, and other respiratory symptoms. Symptoms reported: wheezing, shortness of breath, cough, phlegm, altered pulmonary function, bronchodilation, spontaneous pneumothorax.

How the study worked

Systematic review using comparative methods between two researchers. Full-text articles were reviewed after abstract screening. Excluded: non-burning marijuana routes, animal studies, editorials, other systematic reviews, commentaries, non-English, and non-respiratory articles. 48 articles categorized by respiratory effects.

What this study cannot tell us

Many studies could not fully separate marijuana effects from tobacco effects due to co-use. Study populations, methods, and definitions varied widely. The acute bronchodilation effect complicates interpretation. Some included studies were small or of lower quality.

How to read the evidence

Systematic review with broad coverage, but underlying studies vary in quality and many cannot separate marijuana effects from tobacco co-use.

When this study was published

Published in 2016. Vaporizing and edible consumption have become more common since, potentially changing the risk profile for many users.

The bigger picture

The respiratory risks of smoked marijuana parallel many of those from tobacco, which is expected given that burning plant material produces similar toxicants. This evidence supports the shift toward non-combustion methods (vaporizing, edibles) as harm reduction strategies for cannabis users.

Questions still open

Do vaporizers and edibles eliminate the respiratory risks? Is there a threshold of smoked marijuana use below which risks are minimal? Does marijuana smoke cause lung cancer independent of tobacco?

Common questions

Does smoking marijuana damage your lungs?

Yes. This review of 48 studies found associations with lung cancer risk, emphysema, COPD, and symptoms like cough, phlegm, and wheezing. The risks come from inhaling combusted plant material.

Is marijuana smoke as bad as tobacco smoke?

Marijuana smoke contains many of the same toxicants as tobacco smoke. This review found similar respiratory risks, though separating the two is difficult because many people smoke both.

Read the original research

A Systematic Review of the Respiratory Effects of Inhalational Marijuana.

Respiratory care, 61(11), 1543-1551

View on PubMed ↗

Citation

Martinasek, Mary P; McGrogan, Jamie B; Maysonet, Alisha. (2016). A Systematic Review of the Respiratory Effects of Inhalational Marijuana.. Respiratory care, 61(11), 1543-1551.