The main types of COPD are emphysema and chronic bronchitis. They differ in the damage they do to the airways and lungs. However, the causes, symptoms, and treatment of the two conditions are similar.

There are four stages of chronic obstructive pulmonary disease (COPD) that range from mild to very severe. A person with mild COPD may not know that they have the condition, while someone with very severe COPD will experience life threatening symptoms.

Keep reading to learn about the types and stages of COPD, including causes, symptoms, and treatment options.

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COPD refers to a group of diseases that cause breathing problems and blockages in airflow. They gradually get worse over time. According to the Centers for Disease Control and Prevention (CDC), nearly 15.7 million people in the United States have a diagnosis of COPD.

The CDC add that COPD is more common in:

  • females, although it is important to note that female smokers are about 50% more likely to develop COPD than men. Also, females with severe COPD have a higher risk of hospitalization and death from respiratory failure.
  • people with a history of asthma
  • individuals aged 65 years and older
  • current or former smokers

A person’s windpipe connects to the lungs, where it divides into many smaller branches. These branches end in small air sacs called alveoli, which have tiny blood vessels known as capillaries running along their walls. Here, oxygen passes from the sacs into the capillaries, and the waste product carbon dioxide passes from the capillaries into the sacs. Breathing involves this exchange of gases.

In someone with healthy lungs, the airways and air sacs are stretchy. This elasticity permits the sacs to inflate when a person breathes in and deflate when they breathe out.

People with COPD have less air going in and out of their airways because of one or more of the following:

  • The airways and sacs become too compliant, especially in emphysema, and lose their elastic recoil, leading to alveolar destruction.
  • The airway walls become thick and inflamed in a manner similar to chronic bronchitis.
  • The airways produce more mucus, which clogs airflow, as seen in people with asthma.

The two main types of COPD are emphysema and chronic bronchitis, but many individuals with COPD can have both.


In emphysema, the alveoli, which are the walls of the air sacs, and the small airways suffer damage. As a result of this damage, the sacs lose their shape and ability to recoil during the expiratory phase of the breathing cycle, resulting in trapped air in the lung. This trapped air continues to distend the alveoli, causing a repeating cycle of airway obstruction.

These changes eventually result in the lungs becoming hyperinflated, which reduces the exchange of gases. This makes it difficult for people to breathe and oxygenate their blood effectively while impairing the ability to breathe out carbon dioxide from the blood.

Chronic bronchitis

In chronic bronchitis, the lining of the airways stays inflamed. This leads to swelling and the formation of large amounts of mucus. These effects make it hard to breathe.

Learn more about the differences between emphysema and chronic bronchitis here.

Below we describe the stages of COPD.

There are multiple classification systems used in diagnosing COPD conditions. The following stages come from the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, which derive from a specific breathing test called spirometry grading.

However, this type of testing only captures one component of COPD severity. For example, two patients with the same result may have different tolerances to exercise, symptoms, and prognoses.

Therefore, other COPD aspects, such as the severity of symptoms, risk of exacerbations, and presence of comorbidities, are important to the patient’s experience of the disease and prognosis.

  • Stage 1: Mild COPD: People have mild limitations to their airflow, and some may also have an ongoing cough. They may cough up sputum, a mixture of mucus and saliva. Someone in this stage may not be aware that their lung function is abnormal.
  • Stage 2: Moderate COPD: In Stage 2, airflow limitation worsens, and people tend to experience shortness of breath during exercise. This is the stage where people usually seek medical attention.
  • Stage 3: Severe COPD: In stage 3, a person experiences an even greater restriction to their airflow, as well as increased shortness of breath. This accompanies a decrease in exercise tolerance. The recurring episodes of worsening symptoms reduce quality of life.
  • Stage 4: Very severe COPD: In stage 4, people have severe airflow limitations and greatly reduced quality of life, while episodes of worsening symptoms may become life threatening.

According to the National Heart, Lung, and Blood Institute (NHLBI), the leading cause of emphysema and chronic bronchitis involves long-term exposure to substances that irritate the airways and lungs. The NHLBI note that the primary sources of irritants include tobacco smoke from:

  • cigarettes
  • cigars
  • pipes

The following irritants can also play a role in the development of COPD:

  • secondhand smoke
  • chemical fumes
  • air pollution

In addition, a genetic condition called alpha-1 antitrypsin deficiency may play a role in developing emphysema. It involves reduced production of a protein that protects the lungs.

Symptoms of emphysema or chronic bronchitis include:

  • an ongoing cough or a cough that produces a large amount of mucus
  • wheezing
  • tightness in the chest
  • a whistling or squeaky sound when breathing
  • shortness of breath, particularly with physical activity

Aside from the above, some people may have frequent colds and flu.

If COPD is severe, symptoms may include:

  • weight loss
  • swelling in the feet, ankles, and legs
  • reduced endurance

While emphysema and chronic bronchitis have no cure, lifestyle changes and medical treatments can help a person feel better and delay the worsening of conditions.


Medications can include bronchodilator inhalers, which relax the muscles surrounding the airways, making it easier to breathe. Below, the NHLBI note the type of inhalers appropriate for different stages:

  • If someone has mild COPD, a doctor may prescribe short-term inhalers.
  • If an individual has moderate-to-severe COPD, a doctor may recommend regular use of short- and long-term bronchodilators.
  • Inhalers accompanied with steroids may be an option for people with severe COPD. These steroids can help reduce inflammation.


Because respiratory infections can cause serious problems for individuals with COPD, doctors may recommend getting vaccines to reduce their risk. These include the flu and pneumonia vaccines.

Oxygen therapy

Oxygen therapy can help people with severe COPD, accord to the NHLBI. A person on this treatment receives the oxygen through a mask or nasal prongs. The NHLBI list the following benefits from this treatment:

  • protecting the heart and other organs
  • a person may perform everyday activities with reduced symptoms
  • better sleep
  • increased lifespan


A lung transplant is a last resort for people with one of the main types of COPD. If a person has emphysema, they have other surgical options, including:

  • removal of damaged lung tissue
  • removal of large air spaces that form when the condition destroys air sacs

Lifestyle changes

Quitting smoking is the most important thing someone with COPD can do. If individuals find this challenging, they may wish to join a support group.

They may also consider asking their family and friends for additional support. It is also helpful for them to avoid secondhand smoke and other irritants in their environment.

People with COPD may have difficulties in eating enough because of their symptoms. If so, they can talk with their doctor about recommendations to help them get enough nutrition. For example, a healthcare professional may advise eating smaller, more frequent meals.

Another lifestyle-related measure involves attending pulmonary rehabilitation, a personalized program that teaches management strategies. The plan may include instruction in breathing techniques and ways to conserve energy.

The two primary types of COPD are emphysema and chronic bronchitis.

The four stages of COPD range from mild to very severe. Some symptoms may include an ongoing cough, shortness of breath, and wheezing.

A primary cause of both COPD types is long-term exposure to tobacco smoke, so doctors strongly urge people with the conditions to stop smoking.

In addition to this, lifestyle changes, such as quitting smoking, or treatments, such as medications and oxygen therapy, can also help.