Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Chronic Obstructive Pulmonary Disease (COPD)

(Chronic Bronchitis; Emphysema)


The Manual's Editorial Staff

Reviewed/Revised Dec 2023
Get the full details
Topic Resources

What is COPD?

COPD is a disease in your lungs that makes it hard to breathe. It's hard to push air out of your lungs. Difficulty pushing air out is called chronic airflow obstruction.

  • Smoking cigarettes is the most common cause of COPD

  • COPD makes you cough and be short of breath

  • Stopping smoking can help keep your airways open

  • Your doctor may give you medicines to help avoid or relieve your symptoms

  • If you have severe COPD, you may need to take other medicines, use oxygen, or undergo pulmonary (lung) rehabilitation

Chronic Obstructive Pulmonary Disease

COPD includes 2 lung disorders—chronic obstructive bronchitis and emphysema. Many people have both disorders.

  • Chronic obstructive bronchitis is a cough that brings up thick fluid (sputum—mucus from your lungs) and lasts for at least 3 months total over 2 or more years in a row, combined with airflow blockage and breathing problems

  • Emphysema is damage to the air sacs in your lungs

What causes COPD?

Smoking cigarettes is the most common cause of COPD. Other common causes are:

  • Smoking cigars or pipe tobacco

  • Breathing in chemical fumes, dust, pollution, or heavy smoke

  • A genetic tendency (that is, you have a family history of COPD)

What are the symptoms of COPD?

COPD takes years to develop and get worse.

In your 40s or 50s, you may have:

  • A mild cough that brings up clear sputum (mucus from your lungs), usually in the morning

  • Shortness of breath when you exercise or move around

In your 60s, you may have:

  • More trouble breathing, especially if you smoke

  • Pneumonia Pneumonia and other lung infections that may require hospital stays

  • Weight loss

  • Morning headaches

  • Sometimes swelling of your legs

  • Sometimes coughing up blood

After you've had COPD for a long time, you may notice:

  • Your chest is bigger because air is trapped in your lungs

  • Your skin has a blue tint because the oxygen in your blood is low

  • You're short of breath even when you're not doing anything

Symptoms of COPD flare-ups

A flare-up of COPD is a sudden worsening of your symptoms. Flare-ups can happen at any age. They're usually caused by breathing in pollution or pollen in the air. They're also caused by getting a cold, flu, or other sickness that affects your breathing. See your doctor right away if you have these symptoms:

  • Cough that may produce more yellow or green sputum

  • Shortness of breath even when you're resting

  • Sometimes fever or body aches

A serious flare-up can lead to a dangerously low level of oxygen in your blood (a condition called acute respiratory failure). Go to an emergency room right away if you have these symptoms:

  • Severe shortness of breath (feeling like you're drowning)

  • Anxiety or confusion

  • Sweating

  • Bluish skin caused by low oxygen in your blood

How can doctors tell if I have COPD?

How do doctors treat COPD?

Doctors can't fix the damage in your lungs and airways.

If you're a smoker, you need to stop smoking to keep COPD from getting worse. Doctors may give you medicines to help you stop smoking, such as nicotine gum or a patch.

Doctors may also give you medicines to increase airflow and make it easier to breathe. Some medicines are used to prevent symptoms. Other medicines are used to relieve symptoms. You take some COPD medicines through an inhaler. This allows you to breathe medicine directly into your lungs.


To treat serious COPD symptoms or flare-ups, you may need to stay in the hospital. If an infection has caused the flare-up, you may need antibiotics.

What can I do if I have COPD?

Change certain behaviors

Plan ahead

If your COPD becomes very serious, you'll need help with daily living and medical care. People with advanced COPD have a higher chance of getting sick or dying from heart problems, blocked arteries, or lung problems such as pneumonia or lung cancer. You may need a breathing machine to stay alive.

To prepare yourself, talk with your family members about the type of medical care you want if you're no longer able to make decisions about your own care. Your decisions should be written down in legal documents called advance directives Advance Directives Health care advance directives are legal documents that communicate a person’s wishes about health care decisions in the event the person becomes incapable of making health care decisions. There... read more .

quiz link

Test your knowledge

Take a Quiz!