What is COPD (chronic obstructive pulmonary disease)?

COPD is an umbrella term for a range of progressive lung diseases. Chronic bronchitis and emphysema both can result in COPD. A COPD diagnosis means you may have one of these lung-damaging diseases or symptoms of both. COPD can progress gradually, making it increasingly difficult to breathe over time.

Chronic bronchitis

Chronic bronchitis irritates your bronchial tubes, which carry air to and from your lungs. In response, the tubes swell and mucus (phlegm or “snot”) builds up along the lining. The buildup narrows the tube’s opening, making it hard to get air in and out of the lungs.

Small, hair-like structures on the inside of the bronchial tubes (called cilia) normally move mucus out of the airways. But the irritation from chronic bronchitis and/or smoking damages them. The damaged cilia can’t help clear mucus.


Emphysema is the breakdown of the walls of the tiny air sacs (alveoli) at the end of the bronchial tubes, in the “bottom” of the lung. The lung is like an upside down tree. The trunk is the windpipe or “trachea,” the branches are the “bronchi,” and the leaves are the air sacs or “alveoli .” The air sacs play a crucial role in transferring oxygen into your blood and carbon dioxide out. The damage caused by emphysema destroys the walls of the air sacs, making it hard to get a full breath.

How common is COPD?

COPD affects nearly 16 million Americans, or about 6% of the U.S. population.

Who gets COPD?

The primary cause of COPD is smoking. But not all smokers develop the disease. You may be at higher risk if you:

  • Are a woman.
  • Are over the age of 65.
  • Have been exposed to air pollution.
  • Have worked with chemicals, dust or fumes.
  • Have alpha-1 antitrypsin deficiency (AAT), a genetic risk factor to develop COPD.
  • Had many respiratory infections during childhood.

What causes COPD?

Smoking tobacco causes up to 90% of COPD cases. Other causes include:

  • Alpha-1 antitrypsin (AAT) deficiency, a genetic disorder.
  • Secondhand smoke.
  • Air pollution.
  • Workplace dust and fumes.


Tobacco smoke irritates airways, triggering inflammation (irritation and swelling) that narrows the airways. Smoke also damages cilia so they can’t do their job of removing mucus and trapped particles from the airways.

AAT deficiency

AAT (alpha-1 antitrypsin deficiency) is an uncommon, inherited disorder that can lead to emphysema. Alpha-1 antitrypsin is an enzyme that helps protect lungs from the damaging effects of inflammation. When you have AAT, you don’t produce enough of the enzyme, called alpha-1 antitrypsin. Your lungs are more likely to become damaged from exposure to irritating substances like smoke and dust.

What are signs of chronic obstructive pulmonary disease (COPD)?

  • Cough with mucus that persists for long periods of time.
  • Difficulty taking a deep breath.
  • Shortness of breath with mild exercise (like walking or using the stairs).
  • Shortness of breath performing regular daily activities.
  • Wheezing.

If I am having chronic obstructive pulmonary disease symptoms, how do I determine when I need to call my doctor?

If you are having any of the symptoms described below, don't wait for your next appointment to call your doctor. Report these symptoms promptly, even if you don't feel sick. DO NOT wait for symptoms to become so severe that you need to seek emergency care. If your symptoms are discovered early, your doctor might change your treatment or medications to relieve your symptoms. (Never change or stop taking your medications without first talking to your doctor).

Note: Remember that warning signs or symptoms might be the same or different from one flare-up to another.

Non-emergency care

Talk to your doctor on the phone within 24 hours if you have these changes in your health:

  • Shortness of breath that has become worse or occurs more often. Examples:
    • Unable to walk as far as usual
    • Need more pillows or have to sit up to sleep because of breathing difficulty
    • More tired because you're working harder to breathe
    • Need breathing treatments or inhalers more often than usual
    • Wake up short of breath more than once a night
  • Sputum (mucus) changes including:
    • Changes in color
    • Presence of blood
    • Changes in thickness or amount (more than you usually have or more than you are able to cough out)
    • Odor
  • More coughing or wheezing
  • Swelling in your ankles, feet, or legs that is new or has become worse and doesn't go away after a night's sleep with your feet up
  • Unexplained weight loss or gain of 2 pounds in a day or 5 pounds in a week
  • Frequent morning headaches or dizziness
  • Fever, especially with cold or flu symptoms
  • Restlessness, confusion, forgetfulness, slurring of speech, or irritability
  • Unexplained, extreme fatigue or weakness that lasts for more than a day

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