A lung abscess is a cavity filled with pus. In most cases, it’s the result of a bacterial infection in lung tissue. The infection causes lung tissue to die. Pus collects in the resulting space.

A lung abscess can be challenging to treat, and it can also be life threatening.

If a lung abscess lasts for under 4 to 6 weeks, it’s considered acute. A lung abscess that lasts for longer than that is considered chronic.

The most noticeable symptom of a lung abscess is a productive cough. The contents that are coughed up may be bloody or pus-like, with a foul odor.

Other symptoms include:

Lung abscesses can be classified as primary or secondary. They have different causes and develop from different strains of bacteria.

Primary lung abscess

Primary abscesses are caused by an infection within the lung.

Alcohol use disorder is the condition most likely to make a person susceptible to developing a lung abscess, according to a 2015 study.

People with alcohol use disorder often experience bouts of vomiting and altered levels of consciousness. These complications increase the likelihood of a person inhaling stomach contents and bacteria into the lungs, which can cause an infection.

People who misuse alcohol often have weakened immune systems due to poor overall health and malnutrition, which also makes it easier to develop an infection.

Pneumonia, including a type known as aspiration pneumonia, can also cause a primary lung abscess.

Aspiration pneumonia is an infection that develops after food or secretions from the mouth, stomach, or sinuses are inhaled into the lungs instead of going into the esophagus. It’s a very common cause of primary abscesses.

Aspiration of food or secretions occurs most often while someone is sedated or unconscious, either as a result of intoxication or anesthesia.

The inhaled material is often damaging to lung tissue. It’s also typically filled with bacteria, either from an infection or from normal bacteria found in the mouth, respiratory tract, or stomach.

Secondary lung abscess

Secondary abscesses are caused by anything other than an infection that starts in the lung. Examples include:

Secondary lung abscesses are less common than primary lung abscesses.

People with alcohol use disorder or who have recently been ill (especially with pneumonia) have a higher risk of developing a lung abscess.

Other people who are also at risk include those with weakened immune systems from:

The risk is high for people who have recently been under anesthesia or sedation, and those who have been unconscious as a result of injury or illness.

Inhaling a foreign object that blocks a large airway is also a risk factor.

To diagnose a lung abscess, a doctor will first look at your health history. They’ll want to know about recent operations when anesthesia was used.

If they suspect an abscess, they’ll analyze your sputum or pus.

The doctor might also use imaging techniques, such as an X-ray or a CT scan, to look at where the infection is located in the lungs and rule out other conditions, such as cancer or emphysema.

For more serious infections, the doctor might take a sample of fluid from the area of the abscess using an instrument called a bronchoscope.

If the doctor thinks a foreign object has entered your lungs, they might insert a bronchoscope into the windpipe to locate it.

Antibiotics are the primary treatment for a lung abscess. Experts typically recommend that treatment lasts anywhere from 3 weeks to 8 weeks. However, treatment might be necessary for 6 months or longer in some cases.

The doctor may also suggest lifestyle changes, such as avoiding smoking if you smoke, and drinking more fluids.

In some cases, more invasive procedures or surgery may be necessary. A tube can be inserted into the lungs to drain pus from the abscess, or a surgical procedure may be required to remove infected or damaged lung tissue.

In rare cases, a lung abscess can rupture, or burst. This is a serious medical concern. Surgical treatment may also lead to complications.

Potential complications following the rupture or surgical treatment of an abscess are:

  • Empyema. In empyema, a large collection of infected fluid accumulates around the lung near the abscess. This condition can be life threatening. Prompt medical care is needed so the fluid can be removed.
  • Bronchopleural fistula. A bronchopleural fistula is an abnormal connection that develops between a large airway inside your lung and the space in the lining around the outside of your lung. Surgery or bronchoscopy can correct it. In bronchoscopy, a bronchoscope and sealants can close the fistula.
  • Bleeding from your lung or chest wall. This can be a small amount of blood or a lot of blood, which is life threatening.
  • Infection spreading to other parts of the body. If the infection leaves your lung, it can then produce abscesses in other parts of your body, including your brain.

A primary lung abscess that’s treated with antibiotics heals without complications about 90 percent of the time. Secondary lung abscesses have a higher chance of death. Getting treatment as early as possible may improve the outlook.

People with suppressed immune systems, underlying health conditions, or no access to healthcare are more susceptible to adverse outcomes.

To find a no- or low-cost healthcare clinic, use the Health Resources and Services Administration search tool. Telemedicine apps may also be an option to consider.