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Does Smoking Marijuana Cause Lung Cancer?

Marijuana is a drug that can cause a euphoric, relaxing feeling. Research indicates that it also can play a role in pain relief and help with symptoms of other conditions1. As of early 2024, medical marijuana use was legal in 38 states, and recreational use was legal in 24 states2. However, marijuana use remains illegal at the federal level, which has complicated efforts to research the long-term effects of the drug.

Given the adverse effects of tobacco smoke on the lungs3, many physicians have considered whether marijuana may also contribute to lung cancer and other debilitating diseases. Regional Cancer Care Associates (RCCA) specializes in treating cancer and blood disorders with a team of expert medical oncologists and hematologists. Here, RCCA addresses the question, “Does smoking marijuana cause lung cancer?” and discusses research into the effects of smoking marijuana on the lungs.

Young person smoking marijuana outdoors

What Is in Marijuana?

Marijuana is a widely used drug that can provide pain-relieving benefits. Some research suggests marijuana use is increasing in the U.S., especially among young adults4. People use marijuana as a treatment for pain associated with chronic medical conditions. While research is evaluating marijuana’s efficacy in treating various conditions, there is still relatively little known about its association with lung cancer.

However, research conducted to date has found that marijuana contains many of the same cancer-causing substances as tobacco. These substances include:

  • Benzene
  • Tar
  • Cyanide
  • Ammonia
  • Carbon monoxide
  • Polycyclic aromatic hydrocarbons

It should be noted, however, that many of these substances also are found in tobacco cigarettes. One challenge researchers have faced in exploring a link between marijuana use and lung cancer arises from the fact that many people who smoke marijuana also smoke cigarettes, making it difficult to understand the relative contribution of each behavior to lung cancer risk.

Does Smoking Marijuana Cause Lung Cancer?

Medical researchers have been and continue to research the effects of smoking marijuana on the lungs. This includes determining if smoking marijuana causes lung cancer. Further research is needed before scientists can say definitively that smoking marijuana does or does not cause lung cancer.

That said, the findings of some significant studies suggest that smoking marijuana does not cause lung cancer. One study looked at the relationship between marijuana use and the risk of cancer in the lungs and aerodigestive tract. The results revealed that a correlation between even long-term or heavy marijuana use and lung cancer risk is not strong5. However, researchers also acknowledged the potential for bias or error in their measurements.

Another study involving a limited number of epidemiological studies offered similar results. The findings suggested no link between light or moderate marijuana use and an increased risk for lung or upper airway cancer6. The same study found mixed evidence about the risk of heavy, long-term use of marijuana. However, it also noted that the risk for pulmonary complications even of regular heavy marijuana use is much lower than tobacco use, despite both substances having carcinogenic properties.

Other Considerations for Marijuana Use and Lung Cancer Risk

Ultimately, more research is necessary to better understand the risk between marijuana use and one’s risk for lung cancer. In addition to studying the properties of marijuana, researchers may consider other factors in future studies.

For example, marijuana smokers tend to smoke differently than tobacco smokers. They often hold the smoke in their lungs for longer and inhale the smoke deeply to get the full effect of the marijuana. This practice also leaves harmful carcinogens in the lungs longer, increasing a person’s exposure to substances such as tar, ammonia, and cyanide.

The benefits versus the risk of smoking marijuana is another important research topic. Although smoking marijuana can cause potential health problems, it also can play a role in relieving symptoms of chronic diseases. As more states legalize marijuana, some physicians recommend the drug for relief of pain and anxiety. Beyond smoking, patients can also explore other marijuana ingestion methods, such as edibles or tinctures.

Before using marijuana to manage pain, anxiety, or other health issues, people should discuss their options with their physicians, who may offer other approaches with fewer potential side effects.

Smoking and Lung Cancer

Smoking and inhaling substances can harm the lungs. This is true regardless of the type of smoke a patient inhales. Inhaling smoke can lead to scarring on the lungs and can irritate the lungs’ lining. That makes it more challenging for people to recover from respiratory infections. While more research must be completed, the American Lung Association notes that visits to healthcare centers for respiratory diseases are more common among marijuana smokers than nonsmokers.

People who frequently smoke marijuana can also develop a condition called acute bronchospasm. Acute bronchospasm occurs when irritants invade the airways. Beyond marijuana and tobacco smoke, irritants with the potential to induce spasms include pollen and dust. These irritants can cause airways to become constricted or narrowed. In turn, this can cause symptoms such as:

  • Difficulty breathing
  • Shortness of breath
  • Coughing
  • Wheezing

Those who smoke frequently can also develop a condition called chronic bronchitis. Chronic bronchitis can continue throughout a patient’s life and must be treated regularly to provide relief from symptoms. Chronic bronchitis occurs when marijuana or tobacco smoke inflames the airways. This disease can cause symptoms including:

  • Difficulty breathing
  • Excessive production of mucus
  • Coughing

Beyond smoking marijuana in cigarette form, some people prefer vaping products due to their convenience and ease. Vaping produces less odor than traditional marijuana products, and users do not need to prepare a vaped product before smoking. However, researchers believe that vaping products – including those that deliver substances other than marijuana – are still harmful.

One concern is that many vaping products come from unregulated sources, meaning people do not truly know what is in the products. In addition, inhaling substances into the lungs via vaping can cause scarring and other lung problems, just as traditional smoking can.

Find Support for Lung Cancer Treatment at RCCA

With more than 20 locations across the New Jersey, Connecticut, Maryland, and the Washington, DC area, Regional Cancer Care Associates is here for patients seeking treatment for lung cancer, other cancers, and blood disorders. RCCA’s conveniently located community-based offices are staffed by highly experienced, dedicated medical oncologists and hematologists who offer the latest therapies, access to clinical trials, and compassionate, comprehensive care. For more information, request an appointment or contact us today.

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For more information or to schedule an appointment,
call 844-346-7222. You can also schedule an appointment by calling the RCCA location nearest you.


Regional Cancer Care Associates is one of fewer than 200 medical practices in the country selected to participate in the Oncology Care Model (OCM); a recent Medicare initiative aimed at improving care coordination and access to and quality of care for Medicare beneficiaries undergoing chemotherapy treatment.