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Lung Abscess

Lungs with a bacterial infection on one side.
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Written by Laura Henry, MD.
Resident in the Department of Otolaryngology-Head & Neck Surgery at the University of Pennsylvania
Last updated May 20, 2024

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A lung abscess is a bacterial infection that occurs in the lung and causes tissues to die while a pus-filled cavity develops in its place.

What is a lung abscess?

A lung abscess is a large collection of pus in the tissue of the lungs that results from a bacterial infection. Bacteria that should not normally be found in the lungs causes inflammation that leads to a breakdown of the lung tissue, thus producing the pus.

Symptoms vary depending on whether the abscess is acute or chronic. They may include fever, night sweats, fatigue, weight loss, a cough with mucus or blood, and chest pain when breathing.

Once a diagnosis has been made by an X-ray or further imaging, the main method of treatment is antibiotics to rid the body of infection. Surgery is rarely required.

You should visit your primary care physician within the next 24 hours. Your doctor will confirm the diagnosis with an X-Ray. Treatment for a lung abscess involves prescription antibiotics.

Lung abscess symptoms

Lung abscesses can be acute or chronic conditions. Symptoms present for greater than four weeks indicate a chronic form of lung abscess.

General symptoms

Symptoms that will affect the whole body in cases of lung abscesses include the following.

  • Fever: Fever is a common symptom of many different types of infections, including lung abscesses. In the case of a bacterial infection, immune cells in our body, called macrophages, send out signals (IL-1 and TNF) to the rest of the body to mount a full immune response. These signaling molecules provide feedback to the hypothalamus, the area of our brain responsible for regulating our body temperature.
  • Night sweats: Night sweats are defined as sweating so extensively at night that you soak through your clothes or sheets. Night sweats are closely tied to the fever that often accompanies lung abscesses. Someone with a lung abscess may notice sweating at night but not during the day because of fluctuations in their baseline body temperature. If you have a very slight fever throughout the day, the increase in temperature may not be substantial enough to trigger your body to start sweating. However, when this fever persists at night when your body is supposedly at its coolest, the temperature difference can produce sweating.
  • Fatigue: People with a lung abscess will often complain of fatigue or feeling overly tired or lethargic throughout the day as the body exerts a lot of energy to mount an immune response to fight the infection. This increased energy consumption leaves less energy for activities of daily living.
  • Weight loss: People with a lung abscess may notice weight loss,especially if their condition becomes chronic. The idea behind weight loss as a symptom of this condition is very similar to that of fatigue. The body's efforts to mount an immune response and fight the infection requires energy. Since fighting the infection leads to a higher energy need, more of the calories we eat are used up, potentially leading to weight loss.

Lung-specific symptoms

Symptoms specific to the lungs that will likely be experienced with lung abscesses include the following.

  • Cough: People with a lung abscess often develop a cough as the inflammatory cells fighting the infection can irritate the lung tissue. Our lung tissue naturally produces about a liter of mucus per day. Mucus is made up of water as well as other cellular products of normal tissue breakdown. In the case of a lung abscess, there is substantially more tissue breakdown and therefore more mucus. This increased mucus content and irritation in our lungs can lead to a cough that expectorates phlegm. Depending on the type of bacteria involved in this infection, the phlegm may appear yellow or green.
  • Coughing up blood: The tissue of the lungs has a high density of blood vessels, as this is where our blood gets oxygen before it goes to the rest of the body. If the lung abscess starts eroding into one of these blood vessels, you may notice blood when coughing up mucus. This results in coughing of blood (hemoptysis). This condition can become very serious if the abscess erodes into a major blood vessel, potentially leading to hemorrhage. Life-threatening bleeding is considered greater than 100 to 600 mL of blood within 24 hours.
  • Chest pain with breathing: Pleurisy is the term used to describe chest pain when breathing. Most people feel this pain as they inhale, as the increased capacity of air in the lungs stretches the tissue and produces pain. The source of this pain is the body's immune response to the infection. This immune response can be irritative or damaging to tissues. When it involves the pleura, the lining of tissue around the lungs that stretches with breathing, you can feel chest pain when inhaling.

Lung abscess causes

The most common reason that infection-causing bacteria make their way into the lungs is through aspiration. The aspiration event usually occurs when someone with impaired consciousness or swallowing ability breathes in saliva from the mouth that contains these bacteria instead of swallowing it. Other causes include gum disease, an impaired coughing reflex, cancers, immune deficiency, and septic pulmonary emboli.

Gum disease

People with gum disease, like gingivitis, are more likely to develop lung abscesses if their saliva goes down their windpipe instead of being swallowed. Gingivitis and other periodontal diseases occur because of a large population of bacteria in the mouth. This increased number of bacteria, if aspirated, are then able to more easily colonize the tissue of the lung, creating an abscess.

Impaired coughing reflex

When saliva goes down the trachea, a coughing reflex is triggered as the body's attempt to force the saliva back up this windpipe so that it can be swallowed into the esophagus, the right path for saliva and food. However, impaired consciousness reduces this coughing reflex, increasing the likelihood of swallowing bacteria. Some people with neurologic conditions affecting their brain stem can also have an impaired coughing reflex. Common reasons for impaired consciousness and subsequent aspiration events include:

  • Alcohol intoxication
  • General anesthesia
  • Drug use
  • Stroke

Mouth, throat, or cancers of the airway

Some people are predisposed to aspiration of oral contents despite intact consciousness. People with mouth and throat cancers may experience structural changes in their oral cavity, making it more difficult to properly swallow. People with a lung tumor or a foreign object stuck in their lungs (swallowed) may also develop a lung abscess. People with these obstructions may try to cough up bacteria-containing mucus but are unable to do so because of these blockages. As such, the bacteria then remain in the lung tissue and can cause tissue breakdown and abscess formation.

Immune deficiency

People with insufficient immune systems are also susceptible to lung abscesses. Such immunodeficiency may include HIV and those on immunosuppressants. Normally, if small amounts of bacteria make their way to our lungs, our immune system is able to fight them off without ever causing a problem. However, in those with impaired immune function, these bacteria have the opportunity to multiply, potentially leading to abscess formation.

Septic pulmonary emboli

A rarer cause of a lung abscess is septic pulmonary emboli. This occurs when bacteria colonizing tissue elsewhere in the body (e.g. the heart valve in endocarditis) dislodge from that tissue and move through the bloodstream to the lungs.

Treatment options and prevention for a lung abscess

If you experience the symptoms described and are suspected to have a lung abscess, a chest X-ray is usually the first diagnostic step. On these X-rays, an abscess will usually appear as a rounded lesion in the lungs with air and fluid (pus). If a more detailed picture is needed, a CT scan may be done as well. When this imaging demonstrates a lung abscess, your physician must determine if this is due to an aspiration event or if a tumor or foreign object is lodged in place and blocking the outflow tract and often can be seen on X-ray or CT.

In addition to pursuing chest imaging, a provider may take some of your coughed-up mucus and send it to the pathology lab for culture. This is helpful in that it sometimes allows your physician to choose the most directed antibiotic. However, it can be difficult to perform this analysis since the coughed-up mucus may contain bacteria from the throat or mouth as it made its way back up, therefore not accurately reflecting what is in the lungs.


Antibiotics are the mainstay of therapy for lung abscesses. If you have inhaled oral contents, the antibiotic chosen will likely cover anaerobes, a class of bacteria most commonly found in the mouth.

  • Type: While the specific anaerobe-covering antibiotic is often based on physician preference, ampicillin-sulbactam or a carbapenem are two types of antibiotics that are commonly chosen. These antibiotics are first given intravenously (IV) until you start to show clinical improvement. Most people will start to improve on antibiotics and can be switched to an oral regimen.
  • Duration: The duration of antibiotic therapy has been the subject of much research without a specific numerical conclusion. Usually, months of antibiotics will be necessary. The current practice is to continue treating until the chest X-ray no longer demonstrates the abscess or until the hole in the lungs left by the abscess stays consistently small.


Surgery is rarely performed for lung abscesses. Surgery may be indicated if you're not responding to extended courses of antibiotic therapy. A non-response, while rare, can be due to many factors, including bacteria that are resistant to a number of drug therapies.

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When to seek further consultation for a lung abscess

You should seek further consultation if you experience fever, night sweats, cough, and weight loss; however, a number of diagnoses will have to be considered if you present with these symptoms.

If you are experiencing chest pain or coughing up blood

You should always seek immediate medical attention for these symptoms, as they may be indicative of a life-threatening condition.

Questions your doctor may ask to determine lung abscess

  • Have you experienced any nausea?
  • Do you have a sore throat?
  • Are you sick enough to consider going to the emergency room right now?
  • How severe is your fever?
  • Have you lost your appetite recently?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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