A to Z



Chronic obstructive pulmonary disease (COPD) is a progressive lung disease that makes it difficult to breathe. “Progressive” means that the disease gets worse over time.

Approximately 12 million people in the United States have been diagnosed with COPD. Many more may be affected and not know they have it.

Science & Research

2012 - News ~ Marijuana Smoke Not as Damaging as Tobacco, Says Study.

2011 - Study ~ Effects of smoking cannabis on lung function.

2011 - Study ~ Cannabinoid effects on ventilation and breathlessness: A pilot study of efficacy and safety.

2011 - Study ~ Beneficial effects of cannabinoids (CB) in a murine model of allergen-induced airway inflammation: role of CB1/CB2 receptors.

2010 - Study - Effects of cannabis on lung function: a population-based cohort study.

2009 - Study ~ Marijuana. Respiratory tract effects.

2009 - Study ~ Marijuana and chronic obstructive lung disease: a population-based study.

2009 - Patent ~ US Patent Application 20090197941 - Pharmaceutical Compositons for the Treatment of Chronic Obstructive Pulmonary Disease.

2009 - News - Smoking Pot, Cigarettes Ups COPD Risk.

2009 - News - Does smoking marijuana increase the risk of chronic obstructive pulmonary disease?

2009 - Study - Marijuana and chronic obstructive lung disease: a population-based study.

2007 - Study ~ Effects of Marijuana Smoking on Pulmonary Function and Respiratory Complications: A Systematic Review.

2007 - Study ~ No Decrease in Pulmonary Function Associated with Long-Term Cannabis Smoking, Study Says.

2005 - Study ~ The cannabinoid receptor agonist WIN 55212-2 inhibits neurogenic inflammations in airway tissues.

2005 - Lecture - THC effective in appetite and weight loss in severe lung disease (COPD).

2005 - News - Researchers to test if cannabis ingredient can help COPD patients.

2005 - News ~ THC effective in appetite and weight loss in severe lung disease (COPD).

1997 - News - Heavy Long-Term Marijuana Use Does Not Impair Lung Function.

1997 - Study - Heavy Habitual Marijuana Smoking Does Not Cause an Accelerated Decline in FEV with Age.

1968 - Study - Byssinosis, Chronic Bronchitis, and Ventilatory Capacities in Workers Exposed to Soft Hemp Dust.

Heavy Long-Term Marijuana Use Does Not Impair Lung Function

April 3, 1997

April 3, 1997, Los Angeles, CA: Habitual marijuana smokers do not experience a greater annual rate of decline in lung function than nonsmokers, according to the latest findings by researchers at the University of California at Los Angeles (UCLA) School of Medicine.

The results of the eight-year study appear in Volume 155 of the American Journal of Respiratory & Critical Care Medicine. Dr. Donald P. Tashkin, who headed the study, is one of America's foremost experts on marijuana smoking and lung function.

"Findings from the present long-term, follow-up study of heavy, habitual marijuana smokers argue against the concept that continuing heavy use of marijuana is a significant risk factor for the development of [chronic lung disease]," concluded the UCLA study. "Neither the continuing nor the intermittent marijuana smokers exhibited any significantly different rates of decline in [lung function]" as compared with those individuals who never smoked marijuana.

Researchers added: "No differences were noted between even quite heavy marijuana smoking and nonsmoking of marijuana." These findings starkly contrasted those experienced by tobacco-only smokers who suffered a significant rate of decline in lung function.

Researchers also failed to find any synergistic effect between marijuana and tobacco cigarettes. According to the report, individuals who smoked both did not suffer any faster rate of decline in lung function than individuals who smoked marijuana alone.

A total of 394 young Caucasian men and women agreed to participate in the study. Researchers classified 131 of the participants as heavy marijuana smokers who did not smoke tobacco cigarettes, while 112 smoked both tobacco and marijuana. An additional 65 men regularly smoked tobacco only and the remaining 86 participants were nonsmokers. All participants were screened for pre-existing chronic chest diseases and found to be healthy upon entering the study.

Each participant underwent pulmonary function testing at the start of the study, and again on multiple occasions over the course of the next eight years. During that interval, a number of patients were lost to follow up, but 255 participants (65 percent) completed the study and were tested again at up to six additional sessions.

The results of this latest long-term study on marijuana and health echo findings reached by an Australian group of researchers at the National Drug and Alcohol Research Centre just one month ago. That study, which involved interviews with 268 marijuana smokers and 31 non-using partners and family members, concluded that the health of long-term marijuana users is virtually no different from that of the general population.

Researchers from both studies cautioned that their results do not imply that regular marijuana smoking is free of all potentially harmful pulmonary effects. Both groups stated that regular marijuana smokers were more likely to suffer mild respiratory problems such as wheezing and bronchitis than nonsmokers.

A summary of the UCLA study appears in the March 1997 edition of Forensic Drug Abuse Advisor.



Top      Home

Researchers to test if cannabis ingredient can help COPD patients

Imperial College London, Press Release, 3rd September 2005

Researchers from Imperial College London are looking for volunteers to test whether cannabinoids, the active ingredient of cannabis, can be used to alleviate the sensation of breathlessness caused by illnesses such as chronic obstructive pulmonary disease (COPD).The team are looking for volunteers aged between 50 and 70, who dont have breathing difficulties.

Dr Elspeth Pickering , clinical research fellow, from Imperial College London and Chelsea and Westminster Hospital, says: "Despite the best efforts of scientists for many years, no one has been able to develop a way to deal with the sensation of breathlessness without suppressing the drive to breathe. Breathlessness can have a major impact on the quality of life for patients with respiratory diseases, and by using a cannabinoid, we hope to find a way to block the mechanism which causes it."

The researchers believe the cannabinoids could be used to reduce the sensation of breathlessness without depressing the respiratory system.

The study will take a morning on two different days, during which time volunteers will be hooked up to a circuit to regulate and measure their breathing. Carbon dioxide will be added to the air breathed by the volunteers, causing the sensation of breathlessness. This is a safe method of simulating breathlessness as the body naturally produces carbon dioxide. Afterwards the volunteers will be given a spray which includes tetrahydrocannabinol (THC), the active ingredient in cannabis, which researchers hope will reduce the sensation of breathlessness.

Dr Anita Holdcroft from Imperial College London and Chelsea and Westminster Hospital, and study leader, adds: "The special formulation of the drug as a spray avoids the harmful effects of smoking cannabis. We hope the drug will stop the sensation of breathlessness, potentially providing a new way to deal with respiratory diseases."

The study will be conducted at Charing Cross Hospital in west London. Volunteers will be paid for their time committed to the study. Volunteers aged between 50 and 70 who dont have breathing difficulties and wish to take part should call 020 8846 1234 ext. 7055 to register their interest.

For further information please contact:

Tony Stephenson
Press Officer
Communications Division
Tel: +44 (0)20 7594 6712
Mobile: +44 (0)7753 739766




Top      Home


Heavy Habitual Marijuana Smoking Does Not Cause an Accelerated Decline in FEV with Age


DP Tashkin, MS Simmons, DL Sherrill and AH Coulson
Department of Medicine, UCLA Schools of Medicine and Public Health, Los Angeles, CA 90095-1690, USA.

To assess the possible role of daily smoking of marijuana in the development of chronic obstructive pulmonary disease (COPD), we evaluated the effect of habitual use of marijuana with or without tobacco on the age-related change in lung function (measured as FEV1) in comparison with the effect of nonsmoking and regular tobacco smoking. A convenience sample of 394 healthy young Caucasian adults (68% men; age: 33 +/- 6 yr; mean +/- SD) including, at study entry, 131 heavy, habitual smokers of marijuana alone, 112 smokers of marijuana plus tobacco, 65 regular smokers of tobacco alone, and 86 nonsmokers of either substance were recruited from the greater Los Angeles community.


FEV1 was measured in all 394 participants at study entry and in 255 subjects (65 %) on up to six additional occasions at intervals of > or = 1 yr (1.7 +/- 1.1 yr) over a period of 8 yr. Random-effects models were used to estimate mean rates of decline in FEV1 and to compare these rates between smoking groups. Although men showed a significant effect of tobacco on FEV1 decline (p < 0.05), in neither men nor women was marijuana smoking associated with greater declines in FEV1 than was nonsmoking, nor was an additive effect of marijuana and tobacco noted, or a significant relationship found between the number of marijuana cigarettes smoked per day and the rate of decline in FEV1. We conclude that regular tobacco, but not marijuana, smoking is associated with greater annual rates of decline in lung function than is nonsmoking.


These findings do not support an association between regular marijuana smoking and chronic COPD but do not exclude the possibility of other adverse respiratory effects.


 Top      Home

Byssinosis, Chronic Bronchitis, and Ventilatory Capacities in Workers Exposed to Soft Hemp Dust

Author information Copyright and License information


A study was made of 93 women and 13 men employed in the spinning department of a factory in Yugoslavia processing soft hemp (Cannabis sativa). There were seven occupational groups, with average concentrations of total airborne hemp dust ranging from 2·9 mg./m.3 to more than 19·5 mg./m.3. Thirtyeight women and 11 men, employed in other departments of the factory with average total dust concentrations below 1·0 mg./m.3, were studied as controls.


In the spinning department 40·6% of the workers had byssinosis and 15·1% had chronic bronchitis (defined as persistent cough and phlegm on most days for as much as three months each year during the last two years). None of the controls suffered from either disease.


After adjustment for age, sitting height, and sex, the F.E.V.0·75 and F.V.C. measured at the beginning of the shift were used to assess the long-term effects of hemp dust on the ventilatory function of the lung. The age-adjusted ratio F.E.V.0·75/F.V.C. was also used. A comparison between the control group and the seven exposed groups showed no meaningful association between ventilatory function and present levels of dust exposure, but byssinotics with chronic bronchitis had a mean age-adjusted F.E.V.0·75/F.V.C. ratio significantly lower than that of workers with neither disease (P<0·05).


Acute effects of hemp dust, measured by the change in F.E.V.0·75 and F.V.C. during the shift, were considerable. There were marked reductions in the mean F.E.V.0·75 and F.V.C. during the shift in all the occupational groups exposed to high concentrations of dust. Byssinotics with chronic bronchitis had a significantly greater mean decrease in F.E.V.0·75 during the shift than the byssinotics without chronic bronchitis, and the workers with neither disease (P<0·02).


There is no doubt that the dust of Cannabis sativa hemp can cause byssinosis and at least temporary impairment of ventilatory function, varying in severity according to the level of dust exposure and the presence of respiratory disease.


Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.5M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.
Top      Home

Smoking Pot, Cigarettes Ups COPD Risk

By Salynn Boyles
WebMD Health News
Reviewed by Louise Chang, MD

April 13, 2009 -- People who smoke both cigarettes and marijuana have a greater risk for developing the progressive lung disease COPD than cigarette smokers who don't smoke pot, a new study shows.

Smokers in the study who reported using both tobacco and marijuana were three times as likely as nonsmokers to have clinically confirmed COPD (chronic obstructive pulmonary disease); people who smoked only cigarettes had a slightly lower risk.

The study is among the first to suggest a synergistic relationship between marijuana and tobacco use among older people who are most at risk for COPD.

"This effect suggests that smoking marijuana may act as a primer, or sensitizer, in the airways to amplify the adverse effects of tobacco on respiratory health," says study researcher Wan C. Tan, MD, of the University of British Columbia and St. Paul's Hospital in Vancouver, Canada.


About 12 million Americans are currently living with a diagnosis of COPD; an equal number are believed to have the disease and not know it, according to the National Heart, Lung and Blood Institute.

In the U.S, the term COPD includes both emphysema and chronic bronchitis. With COPD, breathing becomes more difficult over time.

Largely caused by cigarette smoking, COPD is the fourth leading cause of death in the U.S.

While the link between tobacco and COPD is well established, far less is known about the impact of marijuana use on the lungs.

Some studies have found that even short-term heavy marijuana smoking can worsen lung function, while others have not shown this association.

Even less is known about the combined effects of smoking cigarettes and pot, Tan tells WebMD.

The study by Tan and colleagues included 878 residents of Vancouver, Canada participating in a larger investigation examining COPD prevalence.

Participants were considered tobacco smokers if they had smoked at least 365 cigarettes in their lifetime, and were considered marijuana smokers if they reported having ever smoked pot. The researchers defined "substantial" marijuana use as having smoked at least 50 marijuana cigarettes.

The average cigarette smoker in the study had smoked for 16 years, while the self-described pot smokers had smoked an average of 84 marijuana cigarettes.

When COPD was clinically confirmed though a diagnostic method known as spirometric testing:

  • The incidence of COPD among participants who smoked cigarettes alone was 2.7 times higher than among nonsmokers.
  • The incidence of COPD was 2.9 times higher among participants with a history of smoking both cigarettes and pot, even after controlling for other risk factors for the pulmonary disease.
  • COPD risk among people who smoked marijuana, but not tobacco, was slightly higher than among nonsmokers, but the increase was not statistically significant.

The study appears in the April 14 issue of the Canadian Medical Association Journal.


Top      Home

Does smoking marijuana increase the risk of chronic obstructive pulmonary disease?

CMAJ. 2009 April 14; 180(8): 797–798.
PMCID: PMC2665954
Does smoking marijuana increase the risk of chronic obstructive pulmonary disease?
Donald P. Tashkin, MD
Donald Tashkin is with the Division of Pulmonary and Critical Care Medicine, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, USA
Correspondence to: Dr. Donald P. Tashkin, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles (UCLA), 10833 Le Conte Ave., Los Angeles CA 90095-1690, USA; fax 310 206-5088;
Marijuana is the second most commonly smoked substance worldwide after tobacco.1 The constituents of marijuana smoke are qualitatively and, to a large extent, quantitatively similar to those of tobacco smoke, with the exceptions of Δ9-tetrahydrocannabinol (THC), found only in marijuana, and nicotine, found only in tobacco. Given these similarities, there is concern that the health risks of regular marijuana smoking may be similar to those of habitual tobacco smoking. Chronic obstructive pulmonary disease (COPD), which is associated with high morbidity and mortality, is among those risks.

Over the past 2 decades, studies have addressed the possible relation between smoking marijuana and COPD by systematically assessing respiratory symptoms and measuring lung function in smokers and nonsmokers of marijuana or tobacco.These cross-sectiona more...


Top      Home

Marijuana and chronic obstructive lung disease: a population-based study

CMAJ. 2009 April 14; 180(8): 814–820.
PMCID: PMC2665947
Marijuana and chronic obstructive lung disease: a population-based study
Wan C. Tan, MB, Christine Lo, BSc, Aimee Jong, BSc, Li Xing, MSc, Mark J. FitzGerald, MB, William M. Vollmer, PhD, Sonia A. Buist, MD PhD, and Don D. Sin, MD PhD, for the Vancouver Burden of Obstructive Lung Disease (BOLD) Research Group
From the iCapture Centre for Cardiovascular and Pulmonary Research (Tan, Lo, Jong, Xing, Sin), St. Paul’s Hospital and the University of British Columbia, and the Vancouver General Hospital (FitzGerald), Vancouver, BC; the Oregon Health and Sciences University (Vollmer) and the Kaiser Permanente Center for Health Research (Buist), Portland, USA
Correspondence to: Dr. Wan C. Tan, University of British Columbia, iCapture Centre for Cardiovascular and Pulmonary Research, St. Paul’s Hospital, 1081 Burrard St., Vancouver BC V6Z 1Y6; fax 604 806-8351;
Our aim was to determine the combined and independent effects of tobacco and marijuana smoking on respiratory symptoms and chronic obstructive pulmonary disease (COPD) in the general population.
We surveyed a random sample of 878 people aged 40 years or older living in Vancouver, Canada, about their respiratory history and their history of tobacco and marijuana smoking. We performed spirometric testing before and after administration of 200 μg of salbutamol. We examined the association between tobacco and marijuana smoking and COPD.
The prevalence of a history of smoking in this sample was 45.5% (95% confidence interval [CI] 42.2%–48.8%) for marijuana use and 53.1% (95% CI 49.8%–56.4%) for tobacco use.
The prevalence of current smoking (in the past 12 months) was 14% for marijuana use and 14% for tobacco use. Compared with nonsmokers, participants who reported smoking only tobacco, but not those who reported smoking only marijuana, experienced more frequent respiratory symptoms (odds ratio [OR] 1.50, 95% CI 1.05–2.14) and were more likely to have COPD (OR 2.74, 95% CI 1.66–4.52).
Concurrent use of marijuana and tobacco was associated with increased risk (adjusted for age, asthma and comorbidities) of respiratory symptoms (OR 2.39, 95% CI 1.58–3.62) and COPD (OR 2.90, 95% CI 1.53–5.51) if the lifetime dose of marijuana exceeded 50 marijuana cigarettes. The risks of respiratory symptoms and of COPD were related to a synergistic interaction between marijuana and tobacco.
Smoking both tobacco and marijuana synergistically increased the risk of respiratory symptoms and COPD. Smoking only marijuana was not associated with an increased risk of respiratory symptoms or COPD.
 Top      Home

Effects of cannabis on lung function: a population-based cohort study

Eur Respir J. 2010 Jan;35(1):42-7. Epub 2009 Aug 13.

Effects of cannabis on lung function: a population-based cohort study.

Hancox RJ, Poulton R, Ely M, Welch D, Taylor DR, McLachlan CR, Greene JM, Moffitt TE, Caspi A, Sears MR.

Dunedin Multidisciplinary Health and Development Research Unit, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.

Comment in:


The effects of cannabis on lung function remain unclear and may be different from those of tobacco. We compared the associations between use of these substances and lung function in a population-based cohort (n = 1,037). Cannabis and tobacco use were reported at ages 18, 21, 26 and 32 yrs. Spirometry, plethysmography and carbon monoxide transfer factor were measured at 32 yrs. Associations between lung function and exposure to each substance were adjusted for exposure to the other substance. Cumulative cannabis use was associated with higher forced vital capacity, total lung capacity, functional residual capacity and residual volume.

Cannabis was also associated with higher airway resistance but not with forced expiratory volume in 1 s, forced expiratory ratio or transfer factor. These findings were similar among those who did not smoke tobacco. In contrast, tobacco use was associated with lower forced expiratory volume in 1 s, lower forced expiratory ratio, lower transfer factor and higher static lung volumes, but not with airway resistance.

Cannabis appears to have different effects on lung function from those of tobacco. Cannabis use was associated with higher lung volumes, suggesting hyperinflation and increased large-airways resistance, but there was little evidence for airflow obstruction or impairment of gas transfer.



 Top      Home

THC effective in appetite and weight loss in severe lung disease (COPD)

Patients with the severe lung disease COPD (chronic obstructive pulmonary disease) often suffer from appetite loss and cachexia (weight loss) resulting in reduced general well-being and early mortality. In an open clinical study THC improved appetite and well-being and resulted in weight gain.

18 COPD patients aged 49 to 81 years with a mean body weight of 48.5 kg were included in the study under the guidance of Dr. Karl-Christian Bergmann at the Clinic for Allergies and Asthma in Bad Lippspringe, Germany. In the six months before entering the clinic 7 participants had a constant body weight and 11 lost 2.3 kg on average.

They received 3.3-4.2 mg THC two times daily as oily drops delivered by THC Pharm, half an hour before breakfast and dinner. Mean treatment duration was 16 days resulting in a considerable improvement of appetite, general well-being and functional performance (36 per cent mean increase in walking distance) and an average gain in body weight of 1.5 kg, which is much regarding the short treatment period. Side effects were mild.

(Source: Lecture by K-C Bergmann on 17 March 2005 at the Meeting of the German Society of Pulmonology in Berlin)



Top      Home