The American Lung Association is concerned about the health impacts of marijuana use, especially on lung health. We caution the public against smoking marijuana because of the risk of damage to the lungs.

Scientists are researching marijuana, and the American Lung Association encourages continued research into the effects of marijuana use on lung health.

Marijuana

Marijuana is the most commonly abused drug.1,2 The health effects of marijuana are determined in large part by how it's consumed. Marijuana is smoked using pipes, bongs, paper-wrapped joints, blunts and other devices including those that heat or vaporize marijuana. Marijuana can also be consumed through dozens of different products including e-cigarettes, candy, brownies and other baked goods, capsules, beverages and many more.

While this statement focuses on marijuana and lung health, it's important to note that there are other health concerns outside the lungs attributed to marijuana use that are not addressed here, including neurological and cognitive effects.3-6

Additionally, there are public health concerns associated with pediatric poisonings caused by accidental ingestion of edible marijuana products.7

Marijuana Smoke

Smoke is harmful to lung health.5,6,8 Whether from burning wood, tobacco or marijuana, toxins and carcinogens are released from the combustion of materials. Smoke from marijuana combustion has been shown to contain many of the same toxins, irritants, and carcinogens as tobacco smoke.6-10 Although not as carcinogenic as tobacco smoke,9 marijuana smoke contains toxins and carcinogens similar to those in tobacco smoke.10 

As such, there is concern that it could cause harmful health effects, especially among vulnerable children in the home. Additional research on the health effects of secondhand marijuana smoke is needed.

Lung Health and Marijuana Smoke

Smoking marijuana clearly damages the human lung. Research shows that smoking marijuana causes chronic bronchitis and marijuana smoke has been shown to injure the cell linings of the large airways, which could explain why smoking marijuana leads to symptoms such as chronic cough, phlegm production, wheeze, and acute bronchitis.6,15

Smoking marijuana has also been linked to cases of air pockets in between both lungs and between the lungs and the chest wall, as well as large air bubbles in the lungs among young to middle-aged adults, mostly heavy smokers of marijuana.11

However, it's not possible to establish whether these occur more frequently among marijuana smokers than the general population.6

Smoking marijuana can harm more than just the lungs and respiratory system—it can also affect the immune system and the body's ability to fight disease, especially for those whose immune systems are already weakened from immunosuppressive drugs or diseases, such as HIV infection.4,12

Smoking marijuana hurts the lungs' first line of defense against infection by killing cells that help remove dust and germs as well as causing more mucus to be formed. In addition, it also suppresses the immune system.13 These effects could lead to an increased risk of lower respiratory tract infections among marijuana smokers, although there is no clear evidence of such actual infections being more common among marijuana smokers.6,15 However, retrospective analyses of CT chest scans showed that marijuana-only smokers had greater airway thickening and inflammation as well as emphysema compared to both nonsmokers and tobacco-only smokers.16

Studies have shown that in addition to respiratory infections, smoking marijuana may increase the risk of opportunistic infections as well as the risk of acquiring or transmitting viral infections among those who are HIV positive.17    

Another potential threat to those with weakened immune systems is Aspergillus, a mold that has been shown to cause lung disorders in several case reports. 18-20 It can grow on marijuana, which if then smoked exposes the lungs to this fungus. However, it rarely causes problems in people with healthy immune systems.

"Vaping" Marijuana

There is little known on the potential lung health effects of inhaling marijuana or products made from it through routes other than smoking. However:

  • Use of "vape-pens" to inhale cannabis concentrates or liquids may have similar respiratory health effects as e-cigarette use.
  • "Dabbing" (inhaling flash-vaporized cannabis concentrates) may also cause respiratory problems.

Medical Marijuana

The American Lung Association encourages continued research into the health effects of marijuana use, as the benefits, risks and safety of marijuana use for medical purposes require further study. Patients considering using marijuana for medicinal purposes should make this decision in consultation with their doctor and consider means of administration other than smoking.

Bottom Line

  • Smoking marijuana clearly damages the human lung, and regular use leads to chronic bronchitis and can cause an immune-compromised person to be more susceptible to lung infections.
  • No one should be exposed to secondhand marijuana smoke.
  • Due to the risks it poses to lung health, the American Lung Association strongly cautions the public against smoking marijuana as well as tobacco products.
  • More research is needed into the effects of marijuana on health, especially on lung health.
  1. (SAMHSA, 2024) Know the Negative Effects and Risks of Marijuana Use | SAMHSA
  2. (WHO, 2024) Alcohol, Drugs and Addictive Behaviours (who.int)
  3. Cannabis (Marijuana) DrugFacts | National Institute on Drug Abuse (NIDA) (nih.gov)
  4. Volkow ND, Baler RD, Compton WM, Weiss SRB. Adverse health effects of marijuana use. N Engl J Med. 2014;370(23):2219-27.
  5. Urits I, Charipova K, Gress K, Li N, Berger AA, Cornett EM, Kassem H, Ngo AL, Kaye AD, Viswanath O. Adverse Effects of Recreational and Medical Cannabis. Psychopharmacol Bull. 2021 Jan 12;51(1):94-109. PMID: 33897066; PMCID: PMC8063125.
  6. Volkow ND, Swanson JM, Evins AE, DeLisi LE, Meier MH, Gonzalez R, Bloomfield MA, Curran HV, Baler R. Effects of Cannabis Use on Human Behavior, Including Cognition, Motivation, and Psychosis: A Review. JAMA Psychiatry. 2016 Mar;73(3):292-7. doi: 10.1001/jamapsychiatry.2015.3278. PMID: 26842658.
  7. Van Oyen A, Perlman E, Su MK. The Continued Rise of Unintentional Ingestion of Edible Cannabis in Toddlers-A Growing Public Health Concern. JAMA Pediatr. 2022 Nov 1;176(11):1068-1069. doi: 10.1001/jamapediatrics.2022.3530. PMID: 36215048.
  8. Tashkin DP. Effects of marijuana smoking on the lung. Ann Am Thorac Soc. 2013;10(3):239-47.
  9. Melamede R. Cannabis and tobacco smoke are not equally carcinogenic. Harm Reduct J. 2005 Oct 18;2:21. doi: 10.1186/1477-7517-2-21. PMID: 16232311; PMCID: PMC1277837.
  10. Tashkin DP, Roth MD. Pulmonary effects of inhaled cannabis smoke. Am J Drug Alcohol Abuse. 2019;45(6):596-609. doi: 10.1080/00952990.2019.1627366. Epub 2019 Jul 12. PMID: 31298945.
  11. Mishra R, Patel R, Khaja M. Cannabis-induced bullous lung disease leading to pneumothorax: Case report and literature review. Medicine (Baltimore). 2017 May;96(19):e6917. doi: 10.1097/MD.0000000000006917. PMID: 28489809; PMCID: PMC5428643.
  12. Khoj L, Zagà V, Amram DL, Hosein K, Pistone G, Bisconti M, Serafini A, Cammarata LM, Cattaruzza MS, Mura M. Effects of cannabis smoking on the respiratory system: A state-of-the-art review. Respir Med. 2024 Jan;221:107494. doi: 10.1016/j.rmed.2023.107494. Epub 2023 Dec 5. PMID: 38056532.
  13. Preteroti M, Wilson ET, Eidelman DH, Baglole CJ. Modulation of pulmonary immune function by inhaled cannabis products and consequences for lung disease. Respir Res. 2023 Mar 28;24(1):95. doi: 10.1186/s12931-023-02399-1. PMID: 36978106; PMCID: PMC10043545.
  14. Vásconez-González J, Delgado-Moreira K, López-Molina B, Izquierdo-Condoy JS, Gámez-Rivera E, Ortiz-Prado E. Effects of Smoking Marijuana on the Respiratory System: A Systematic Review. Subst Abus. 2023 Jul;44(3):249-260. doi: 10.1177/08897077231186228. Epub 2023 Sep 20. PMID: 37728136.
  15. Moir D, Rickert WS, Levasseur G, et al. A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chem Res Toxicol. 2008;21(2):494-502. doi:10.1021/tx700275p.
  16. Murtha L, Sathiadoss P, Salameh JP, Mcinnes MDF, Revah G. Chest CT Findings in Marijuana Smokers. Radiology. 2023 Apr;307(1):e212611. doi: 10.1148/radiol.212611. Epub 2022 Nov 15. PMID: 36378033.
  17. Maggirwar SB, Khalsa JH. The Link between Cannabis Use, Immune System, and Viral Infections. Viruses. 2021 Jun 9;13(6):1099. doi: 10.3390/v13061099. PMID: 34207524; PMCID: PMC8229290.
  18. Llamas R, Hart DR, Schneider NS. Allergic bronchopulmonary aspergillosis associated with smoking moldy marihuana. Chest 1978; 73: 871–872.
  19. Hamadeh R, Ardehali A, Locksley RM, York MK. Fatal aspergillosis associated with smoking contaminated marijuana, in a marrow transplant recipient. Chest 1988; 94: 432–433.
  20. Remington TL, Fuller J, Chiu I. Chronic necrotizing pulmonary aspergillosis in a patient with diabetes and marijuana use. CMAJ 2015; 187: 1305–1308.

Page last updated: May 2, 2024

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