What Is COPD?

Chronic obstructive pulmonary disease (COPD) develops slowly over several years. COPD symptoms include wheezing, a chronic cough that produces phlegm, and progressive shortness of breath. COPD is the third leading cause of death in the United States. The disorder includes both chronic bronchitis and emphysema.

Chronic bronchitis

A recurrent problem, chronic bronchitis is defined by the coughing up of phlegm nearly every day for at least three months of the year (for example, every winter) for two or more consecutive years. The condition reduces the diameter of the airways through a combination of airway inflammation and overproduction of mucus.

In the past year, nearly 9 million people in the United States had a diagnosis of chronic bronchitis, resulting in more than 600 deaths. According to the American Lung Association, women are more than twice as likely as men to be diagnosed with chronic bronchitis.


This is a disorder characterized by destruction of lung tissue, including its elastic fibers. By reducing elasticity of the lungs and destroying the walls of some of the air sacs, emphysema leads to the collapse of the airways, reducing airflow.

More than 4 million Americans have emphysema, which is most common among adults age 65 and older. Emphysema claims more than 9,000 lives each year.

COPD causes

Cigarette smoking causes the vast majority of COPD cases. Cigarette smoke is thought to release enzymes that damage elastin, a protein that makes the lungs elastic. Smoking is also believed to inactivate alpha-1 antitrypsin, a protein produced by the liver that normally protects elastin from the action of these enzymes.

About 1 in 2,500 people worldwide has a genetic defect that prevents the secretion of alpha-1 antitrypsin by the liver and increases the risk of developing premature emphysema, especially in smokers. Other factors that raise the risk of emphysema include a family history of COPD, being male, respiratory illnesses in childhood, and work-related exposure to pollutants.

COPD symptoms

Typically, people who develop COPD began smoking at an early age and have a long history of a morning cough that produces phlegm. Lung function often declines slowly over many years. Most people only seek medical advice after age 50 when they begin to notice significant shortness of breath during exertion. As COPD worsens, breathlessness begins to severely limit their activities.

To help identify COPD at its earliest stages before it causes serious lung damage, anyone at risk for the disease should be tested at the first sign of any breathing difficulties. Although lung function tends to decrease slowly, the decline is frequently punctuated by acute episodes of worsening symptoms, usually because of a viral or bacterial infection. These acute episodes are marked by increased shortness of breath, wheezing, and a cough that produces greater than usual amounts of phlegm.

Though acute episodes may be severe enough to be life-threatening, they do not necessarily speed the rate of disease progression. However, continuing to smoke does increase the rate of disease progression. Importantly, the accelerated rate of loss of lung function can be reversed with smoking cessation. Thus, it is imperative that current smokers with COPD stop smoking as soon as possible. COPD may also cause low levels of oxygen in the blood, which can lead to pulmonary hypertension—a rise in pressure in the arteries that carry blood to the lungs. Pulmonary hypertension increases the workload of the right ventricle, one of the lower chambers of the heart, causing it to enlarge. Ultimately, this problem can lead to heart failure.

At advanced stages of COPD, individuals frequently become thin because they find it tiring even to eat and because the work of breathing burns more calories than it does in healthy people. There may be other causes that have yet to be defined.

People in an advanced stage of COPD may become depressed and anxious. The good news is that these problems are treatable. If you are feeling anxious or depressed, it is important to bring these feelings to your doctor’s attention. He or she can refer you to a pulmonary rehabilitation program or a mental health professional who can help you address these issues.

COPD diagnosis

A doctor who suspects COPD will perform a physical exam and listen to the breath sounds with a stethoscope. He or she will also look at the results of spirometry, lung volume, and diffusing capacity tests, which can indicate the presence and severity of COPD, as well as help determine the prognosis.

Imaging tests also help with the diagnosis. A chest X-ray may show an increased volume of air in the lungs and enlargement of the central pulmonary artery, which extends from the heart’s right ventricle to the lungs; this can be seen in pulmonary hypertension. Also, depending on the severity of the disease, changes related to pulmonary hypertension are sometimes visible as abnormalities in the electrical activity of the heart, measured on an electrocardiogram (ECG).

Looking for a genetic cause by measuring alpha-1 antitrypsin levels may be useful when COPD affects a young person or a nonsmoker.

COPD prevention

Steering clear of cigarette smoking is the most obvious and effective way to prevent COPD. Many people try to quit “cold turkey,” but several studies indicate that using nicotine replacement therapy or the oral medication bupropion (Zyban), alone or in combination, can help increase the chances of quitting. The smoking cessation drug varenicline (Chantix) also helps some people kick the habit. It appears to work best for smokers who have not been able to quit using other methods, including nicotine replacement products.

There is some concern that Chantix and Zyban may cause severe mood and behavior changes. Both products carry a black box warning about such changes on the product labels. Behavior changes to look for include hostility, agitation, depressed mood, suicidal thoughts, and/or attempts to commit suicide. If such changes occur, stop taking the medication immediately and tell your doctor.

Some people with a deficiency of alpha-1 antitrypsin may receive some protection from COPD by getting weekly or twice-monthly intravenous (IV) injections of the protein, but such treatments are expensive, inconvenient, and not always effective.

(Originally published Jun. 29, 2016; updated Feb. 24, 2017)

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HealthAfter50 was published by the University of California, Berkeley, School of Public Health, providing up-to-date, evidence-based research and expert advice on the prevention, diagnosis, and treatment of a wide range of health conditions affecting adults in middle age and beyond. It was previously part of Remedy Health Media's network of digital and print publications, which also include HealthCentral; HIV/AIDS resources The Body and The Body Pro; the UC Berkeley Wellness Letter; and the Berkeley Wellness website. All content from HA50 merged into Healthcentral.com in 2018.