Medically Reviewed by
Jason Crawford

Article Last Updated on December 21, 2022

Ever since cannabis legalization began around the world, people have been debating whether cannabis use poses a threat to lung function and if it can increase the chances of getting lung cancer. And even though marijuana is used medicinally to treat certain conditions, can this plant actually cause health problems? And more specifically, can it cause pneumonia?

According to the American Thoracic Society, around 1 million adults are admitted to the hospital yearly and 50,000 die from the disease in the United States alone.

If you are interested in what recent studies say on the subject, read on. We’ll go into how marijuana affects the lungs, whether it can cause infections like pneumonia, and what symptoms you need to be on the lookout for.

What Is Pneumonia?

Pneumonia or bronchopneumonia is an infection that affects the lungs and causes the air sacs to fill up with pus or fluids. The infection ranges from mild to severe depending on your age, your overall health, and the type of germ that’s causing it. Severe cases of pneumonia can be life-threatening, since they can cause kidney failure, respiratory failure, pleural disorders, lung abscesses, and bacteremia (bacteria moving into the bloodstream).

Symptoms of pneumonia can vary from mild to severe and they include nausea, vomiting, chest pain when breathing or coughing, diarrhea, fever, chills, cough usually accompanied with phlegm, as well as shortness of breath.

Types of Pneumonia

Pneumonia can be caused by a bacterial, viral, or fungal infection. The bacterial pneumonia can occur on its own, and the bacteria that cause it include Streptococcus pneumoniae, Legionella pneumophila, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Haemophilus influenzae. 

Viral pneumonia is often mild and it might go away on its own after a few weeks. It’s caused by viruses that infect the respiratory tract like Respiratory syncytial virus (RSV), the common cold and flu viruses, as well as SARS-CoV-2, the virus that causes COVID-19. According to the CDC, some patients that get the coronavirus disease have also had pneumonia in the past.

The third cause of pneumonia is most common in people that have chronic health problems or weakened immune systems. Some of the types of fungal pneumonia include Pneumocystis pneumonia (PCP), Coccidioidomycosis, Histoplasmosis, and Cryptococcus.

Cannabis Smoke And Lung Health

Marijuana smoke contains more than 450 chemicals as well as carcinogens, similar to tobacco smoke. According to the National Institute on Drug Abuse, marijuana smoke is an irritant to the throat and lungs and may cause a heavy cough.

Cannabis smoke, as well as tobacco smoke, affects the lungs and often causes symptoms and side effects like increased sputum, wheezing, shortness of breath, and lung hyperinflation, but they are not equally carcinogenic. (Melamede et al, 2005)

Moreover, depending on the amount of time and frequency of smoking, it may even cause lung diseases. Smoking cannabis has been linked to weakening of the immune system and chronic bronchitis. But when it comes to Chronic Obstructive Pulmonary Disease (COPD), occasional marijuana use is not a risk factor.  (Joshi et al, 2014, Aldington et al, 2008)

Can Smoking Marijuana Cause Pneumonia?

When it comes to marijuana causing pneumonia, scientists have proven that some methods of marijuana consumption may result in pneumonia and other conditions like invasive Aspergillosis, as a result of inhaling contaminated leaves and Pseudomonas when using a bong. (Szyper-Kravitz et al, 2001)

Other research has been done on 74 habitual marijuana smokers and the results suggest that recreational marijuana use “may cause mild but significant, functional impairment predominantly involving large airways which is not detectable in individuals of the same age who regularly smoke tobacco”. (Tashkin et al, 1980)

Using a Bong

The use of bongs for smoking cannabis has been linked to a severe case of Pseudomonas aeruginosa which is necrotizing pneumonia. The patient had smoked marijuana with a bong which resulted in a lung infection that generally results in high morbidity and mortality. Although the patient’s condition improved on pharmacotherapy, it also led to the patient having a trapped lung and impairment in his lung function. So using a bong as a method of marijuana consumption may have caused this patient to develop necrotizing pneumonia. (Kumar et al, 2018)


Vaping, on the other hand, is a newer method of marijuana consumption that has been researched more and more in recent years. Vaping has gained popularity among young adults as a safe alternative to smoking, although recent research shows how that may be a long way from the truth.  

One of the conditions that vaping has been suspected of causing is Acute eosinophilic pneumonia (AEP) which can happen as a result of inhalation exposures. According to a case study in 2019, a college student with no significant medical history was treated with empiric antibiotics and bronchodilators without improvement twice in 10 days. After high-resolution CT scans it was determined that he had acquired Acute Eosinophilic Pneumonia as a result of cannabis vapor inhalation. Vaping may be a public health threat that is yet to be quantified and further studies are needed on the subject. (Antwi-Amoabeng et al, 2019)

Can Medical Marijuana Be an Effective Treatment for Pneumonia?

On the other hand, some medical practitioners prescribe marijuana strains low in tetrahydrocannabinol THC and high in cannabidiol CBD as anti-anxiety medication, anti-inflammatory medication, and for pain management. But often whole plant tinctures or topicals are suggested as the best methods when using medical marijuana as a treatment option. It’s a better option compared to smoking since smoking can cause lung-related health problems.

A study done on rodents shows that smoking cannabis or taking THC pills could have potent airway-dilating effects. The study revealed that the endogenous cannabinoid anandamide had hindered a capsaicin-induced cough and bronchospasm and that marijuana may be used to treat certain types of pneumonia. (Calignano et al, 2000, Ribeiro et al, 2016)


Studies have not linked marijuana smoke to increased lung cancer risk, although smoking weed can cause other serious health effects.

A lot of people who smoke marijuana also smoke tobacco, which in turn, increases the risk for lung damage. Up until now, a lot of the research done on marijuana causing pneumonia is based on a few studies here and there, and most conclusions are preliminary or inconclusive.

Some studies have shown that using a bong resulted in a case of Pseudomonas lung infection, while vaping in one case caused Eosinophilic Pneumonia.

And while the above-mentioned research has shown that cannabis use resulted in pneumonia, some studies show that THC has airway-dilating effects and is used to treat pneumonia.

Although conflicting research exists, it’s certain that marijuana smoke contains several harmful chemicals and marijuana consumption methods like using vaporizers and bongs don’t decrease the amount of dangerous chemicals in marijuana smoke.

Additional Sources

Joshi, M., Joshi, A., & Bartter, T. (2014). Marijuana and lung diseases. Current opinion in pulmonary medicine, 20(2), 173–179. https://doi.org/10.1097/MCP.0000000000000026

Aldington, S., Harwood, M., Cox, B., Weatherall, M., Beckert, L., Hansell, A., Pritchard, A., Robinson, G., Beasley, R., & Cannabis and Respiratory Disease Research Group (2008). Cannabis use and risk of lung cancer: a case-control study. The European respiratory journal, 31(2), 280–286. https://doi.org/10.1183/09031936.00065707

Melamede R. (2005). Cannabis and tobacco smoke are not equally carcinogenic. Harm reduction journal, 2, 21. https://doi.org/10.1186/1477-7517-2-21

Tashkin, D. P., Calvarese, B. M., Simmons, M. S., & Shapiro, B. J. (1980). Respiratory status of seventy-four habitual marijuana smokers. Chest, 78(5), 699–706. https://doi.org/10.1378/chest.78.5.699

Szyper-Kravitz, M., Lang, R., Manor, Y., & Lahav, M. (2001). Early invasive pulmonary aspergillosis in a leukemia patient linked to aspergillus contaminated marijuana smoking. Leukemia & lymphoma, 42(6), 1433–1437. https://doi.org/10.3109/10428190109097776

Kumar, A. N., Soo, C. I., Ng, B. H., Hassan, T., Ban, A. Y., & Manap, R. A. (2017). Marijuana “bong” pseudomonas lung infection: a detrimental recreational experience. Respirology case reports, 6(2), e00293. https://doi.org/10.1002/rcr2.293

Daniel Antwi-Amoabeng, Raheel Islam, “Vaping Is Not Safe: A Case of Acute Eosinophilic Pneumonia following Cannabis Vapor Inhalation“, Case Reports in Pulmonology, vol. 2020, Article ID 9496564, 5 pages, 2020. https://doi.org/10.1155/2020/9496564

Calignano, A., Kátona, I., Désarnaud, F., Giuffrida, A., La Rana, G., Mackie, K., Freund, T. F., & Piomelli, D. (2000). Bidirectional control of airway responsiveness by endogenous cannabinoids. Nature, 408(6808), 96–101. https://doi.org/10.1038/35040576

Ribeiro, L. I., & Ind, P. W. (2016). Effect of cannabis smoking on lung function and respiratory symptoms: a structured literature review. NPJ primary care respiratory medicine, 26, 16071. https://doi.org/10.1038/npjpcrm.2016.71

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.