Cannabis Smoking & Lung Health: Study Reveals Respiratory Risks & Immune Changes

Cannabis Use Linked to Respiratory Issues and Altered Immune Response, New Study Finds

As cannabis legalization expands globally, a growing body of research is examining the long-term health effects of its use. A new study, published in the European Respiratory Journal in January 2026, provides compelling evidence linking cannabis smoking to impaired lung function, increased respiratory symptoms, and notable changes in the immune system. Researchers from Canada, the United States, and the United Kingdom investigated the respiratory health of cannabis users, comparing them to non-smokers and identifying potential risks associated with varying levels of consumption. The findings underscore the need for a more comprehensive understanding of the potential health consequences of cannabis use, particularly as its prevalence continues to rise worldwide.

The study, formally titled “Clinical, physiological, imaging and molecular responses to cannabis smoking: the Canadian Users of Cannabis Smoke (CANUCK) study,” involved 139 individuals who reported cannabis use and a control group of 57 non-smokers. To quantify cannabis exposure, researchers utilized a metric called “joint-years,” defined as the equivalent of smoking one cannabis joint per day for a year. This standardized measure allowed for a more nuanced assessment of the relationship between cannabis consumption and respiratory health outcomes. The research team meticulously analyzed lung function, reported symptoms, and immune cell activity to identify potential correlations.

Categorizing Cannabis Consumption

Participants who reported cannabis use were categorized into three groups based on their level of exposure, measured in joint-years: low consumption (up to five joint-years, representing 44 percent of the cannabis-using group), moderate consumption (more than five to 20 joint-years, 28 percent), and high consumption (more than 20 joint-years, 28 percent). This stratification allowed researchers to examine whether the severity of respiratory effects varied with the intensity of cannabis use. Notably, a significant majority – 84 percent – of the cannabis-using participants also reported current or past use of tobacco or e-cigarettes, a factor that complicates the interpretation of the results, as these substances are known to have detrimental effects on respiratory health.

Impaired Lung Function and Respiratory Symptoms

Compared to the non-smoking control group, individuals who reported cannabis use exhibited poorer lung function, as measured by standard pulmonary function tests. Specifically, cannabis users reported a higher incidence of respiratory symptoms, including chronic cough, increased mucus production, and wheezing. These findings align with previous research suggesting that cannabis smoke, similar to tobacco smoke, can irritate the airways and contribute to respiratory distress. The study also indicated that individuals with high levels of cannabis consumption were more likely to experience bronchitis symptoms.

Immune System Alterations

Beyond assessing lung function and symptoms, the researchers delved into the immunological effects of cannabis smoking. Analysis of cells collected from the respiratory tract revealed significant alterations in the immune system of cannabis users. Specifically, the study identified an increased type-2 immune response, which is typically associated with allergic inflammation, and a weakened type-17 immune response, crucial for defending against certain pathogens. Researchers observed heightened activity of the MUC5AC gene, responsible for regulating mucus production in the airways. This increased mucus production could contribute to the respiratory symptoms reported by cannabis users.

These immune system changes are particularly concerning, as they suggest that chronic cannabis smoking may compromise the lungs’ ability to effectively fight off infections and maintain overall respiratory health. The interplay between cannabis smoke exposure and immune dysregulation warrants further investigation to fully understand the long-term consequences.

Global Cannabis Trends and Public Health Implications

The findings of the CANUCK study are particularly timely given the increasing global trend towards cannabis legalization and normalization. According to a 2023 report by the United Nations Office on Drugs and Crime, the number of people using cannabis worldwide has risen significantly in recent decades. The 2023 World Drug Report estimates that over 269 million people aged 15-64 used cannabis in 2022. As access to cannabis expands, the potential health risks associated with its use, particularly concerning respiratory health.

The researchers emphasize the need for larger, long-term studies to further investigate the health effects of cannabis smoking. Future research should focus on tracking participants over extended periods to assess the progression of respiratory symptoms and immune changes. Studies are needed to determine whether these effects are reversible upon cessation of cannabis use. The German Federal Centre for Health Education (Lungeninformationsdienst) provides resources for those seeking to quit smoking, including cannabis.

Canada-US Relations and Research Collaboration

The collaborative nature of the CANUCK study, involving researchers from Canada, the United States, and the United Kingdom, highlights the importance of international cooperation in addressing complex public health challenges. Canada and the United States, in particular, have a long history of scientific collaboration, despite occasional political tensions. As reported by the Canadian Press in March 2025, research funding between the two countries remains robust, with a focus on areas such as health, environmental science, and technology. The Guardian reported on a meeting between Canadian Prime Minister Mark Carney and UK Prime Minister Keir Starmer in March 2025, where both leaders reaffirmed their commitment to strengthening bilateral ties, including scientific partnerships.

However, the relationship between Canada and the United States has faced challenges in recent years, particularly during the presidency of Donald Trump. As detailed in a Global News report from February 2025, Trump’s “America First” trade policies and rhetoric created significant friction with Canada. The report highlights the trade tensions and political uncertainty that characterized the period, potentially impacting collaborative research efforts. Despite these challenges, the CANUCK study demonstrates the continued value of international scientific cooperation in advancing our understanding of public health issues.

Key Takeaways

• Cannabis smoking is associated with impaired lung function and increased respiratory symptoms.
• Chronic cannabis use can alter the immune response in the lungs, potentially increasing susceptibility to infections.
• The increasing global prevalence of cannabis use underscores the need for further research into its long-term health effects.
• Individuals considering cannabis use should be aware of the potential respiratory risks.

The CANUCK study provides valuable insights into the respiratory health effects of cannabis smoking. As cannabis policies continue to evolve, ongoing research is essential to inform public health recommendations and ensure that individuals are equipped with the knowledge to make informed decisions about their health. Further studies are planned to investigate the impact of different cannabis consumption methods, such as vaping and edibles, on respiratory health. The next major update from the CANUCK research team is expected in the fall of 2026, when preliminary results from a follow-up study will be presented at the International Respiratory Society conference in Barcelona.

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