New Research: Smoking Marijuana and Cigarettes Linked to Increased Lung Damage

Smoking Marijuana Joint

New research indicates that smoking both marijuana and cigarettes significantly increases the risk of lung damage, challenging common beliefs about the safety of marijuana smoking. The study underscores the need for more research in this area to inform public understanding.

According to findings recently presented at the Radiological Society of North America’s annual meeting, combining marijuana and cigarette smoking could result in greater harm to the lung’s air sacs.

Despite widespread beliefs that marijuana smoking is not harmful to the lungs, extensive research has highlighted the dangers of cigarette smoking. However, there’s limited knowledge about the impact of marijuana smoking on its own, and even less is understood about the effects when it’s combined with cigarette smoking.

“Marijuana is the most widely used illicit psychoactive substance in the world, and its use has increased in Canada since the legalization of non-medical marijuana in 2018,” said study co-author Jessie Kang, M.D., cardiothoracic radiologist and assistant professor in the Department of Diagnostic Radiology at Dalhousie University in Halifax, Nova Scotia, Canada. “Currently, not much research exists on the effects of marijuana smoking on the lungs.”

To determine the effects of marijuana and cigarette smoking, researchers for the multicenter prospective study examined the chest CT images of four patient groups: non-smokers, cigarette smokers, marijuana smokers, and combined marijuana and cigarette smokers. Marijuana smokers included in the study had smoked marijuana at least four times a month for two years. Patients who ingested marijuana via edibles or oral drops were excluded from the study.


The researchers found that people who combined marijuana and cigarettes were 12 times more likely to have centrilobular emphysema than non-smokers. Centrilobular emphysema is a type of pulmonary emphysema where the air sacs within the lungs are damaged. This can lead to breathing difficulties and other serious respiratory symptoms.

“The mean number of marijuana smoking years was less than compared to cigarette smokers and combined marijuana and cigarette smokers,” Dr. Kang said. “However, marijuana that is smoked is often unfiltered, which can potentially lead to more damaging particles entering the airways and lungs.”

Airway Changes in a Marijuana and Tobacco Smoker

Airway changes in a 66-year-old male marijuana and tobacco smoker with cylindrical bronchiectasis and bronchial wall thickening (arrowheads) in multiple lung lobes in a background of paraseptal and centrilobular emphysema. Credit: RSNA/Radiology

Combined marijuana and cigarette smokers were three to four times more likely to have airway wall thickening, which can lead to infections, scarring, and further airway damage. Association with marijuana only and smoking only with bronchial wall thickening was not as significant. Similar results were seen with centrilobular and paraseptal emphysema, suggesting that the combination of cigarette and marijuana smoking may have a synergistic role on the lungs and airways.

“With our study, we show that there are physical effects of marijuana smoking on the lungs and that cigarette smoking and marijuana smoking may have a combined damaging effect on the lungs,” Dr. Kang said.

According to Dr. Kang, further research is needed to identify the long-term effects of smoking marijuana.

“There is a common public misconception that marijuana smoking is not harmful,” Dr. Kang said. “More research needs to be done in this area, so the public can make an informed decision on their recreational usage of marijuana.”

Meeting: 109th Scientific Assembly and Annual Meeting of the Radiological Society of North America

Co-authors are Sebastian Karpinski, B.Sc., Paul Sathiadoss, M.B.B.S., Eric Lam, M.Sc., Eric Hutfluss, M.D., O. Osorio, M.D., D. A. Hashem, M.D., Matthew D. F. McInnes, M.D., and Giselle Y. Revah, M.D.

1 Comment on "New Research: Smoking Marijuana and Cigarettes Linked to Increased Lung Damage"

  1. I smoked cigs and cannabis together for about fifteen years. I ga e up the cannabis. I could tell that the both together was more harm than good. I still smoke cigs over thirty years later. I still developed COPD. I could tell a big difference in my breathing function.

Leave a comment

Email address is optional. If provided, your email will not be published or shared.