What Is Inflammation of the Lungs?

What to Know About Pneumonitis

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Lung inflammation, also known as pneumonitis, can be caused by exposure to airborne toxins or irritants, respiratory infections, and lung diseases like asthma or chronic bronchitis. Symptoms may include wheezing, shortness of breath, chest pain, and coughing.

Pneumonitis can be acute (rapidly occurring and severe) or chronic (persistent or recurrent). The diagnosis may involve a physical exam, blood tests, imaging tests, and other procedures. Treatment is typically focused on treating the underlying cause, but anti-inflammatory or immunosuppressant drugs may be prescribed to directly treat the inflammation. Sometimes surgery is needed.

This article explains some common symptoms and causes of pneumonitis. It also discusses how inflammation in the lungs is diagnosed and treated.

Symptoms of Lung Inflammation

Verywell / Nez Riaz

Lung Inflammation Symptoms

Symptoms of pneumonitis can develop very suddenly or gradually over time. The symptoms vary based on the underlying cause, the extent of the inflammation, and your general health.

Symptoms of pneumonitis may include:

  • Fatigue
  • Wheezing
  • Shortness of breath
  • Productive (wet) or non-productive (wet) cough
  • Easy exhaustion with physical exertion
  • Chest discomfort, pain, or tightness

With chronic pneumonitis, a loss of appetite and unintended weight loss are common.


When severe, pneumonitis can limit airflow or lower your ability to absorb oxygen. This can cause hypoxemia (low blood oxygen) or hypoxia (low oxygen in tissues), leading to symptoms like:

  • Extreme restlessness
  • Slow heart rate (bradycardia)
  • Blueish skin (cyanosis)
  • Dizziness or fainting

Over time, chronic lung inflammation can change the thickness, composition, or volume of the airways, leading to a condition known as bronchiectasis. Bronchiectasis is a long-term, progressive condition in which the airways become permanently widened, leading to a build-up of mucus in the lungs and an increased risk of infection.

These changes can also lead to hypercapnia in which it is harder to get carbon dioxide out of the lungs. In cases like this, a mechanical ventilator may be needed to help you breathe.

What Causes Lung Inflammation?

Inflammation is the body's natural response to injury or infection. There are many different reasons why this might occur in the lungs. While inflammation is a means for the body to heal itself, persistent inflammation can cause damage to airways and lung tissues.

Common causes of lung inflammation include:

Respiratory Irritants

When airborne toxins or irritants enter the lungs, the body responds with inflammation. This causes the airways to swell and produce a gooey substance called mucus that surrounds the particles and protects the wall of the airways. Mucus can then be dislodged with coughing.

Some common irritants include:

  • Cigarette smoke
  • Air pollution
  • Industrial aerosols
  • Household ammonia or chlorine
  • Solvents
  • Smoke

You can also have hypersensitivity pneumonitis in which your immune system overreacts to an inhaled irritant and triggers an extreme allergic response with lung inflammation. Dust mites, pollen, and pet dander are common triggers.

Lung Infections

There are many different pathogens (disease-causing agents) that cause lung infections. These include viruses that tend to cause acute infection, bacteria that can cause acute and chronic lung infections, and fungi that tend to cause severe infections in people with compromised immune systems.

Examples include:

  • Common cold
  • COVID-19
  • Flu (influenza)
  • Histoplasmosis
  • Pneumonia
  • Respiratory syncytial virus (RSV)
  • Tuberculosis (Tb)
  • Valley fever (coccidioidomycosis)
  • Whooping cough (pertussis)

Severe lung infections may cause acute respiratory distress syndrome (ARDS), a potentially life-threatening condition in which you cannot get enough oxygen in your blood.


Asthma is a condition in which your airways narrow and swell in response to different airborne triggers or health conditions. It causes episodes of bronchospasm in which the airways spasm violently, causing wheezing and coughing. Mucus might also be produced.

People with poorly managed asthma have a higher risk of pneumonia as a result of persistent lung inflammation.

Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is associated with chronic pneumonitis and an increased risk of bronchiectasis and pneumonia. Cigarette smoking is strongly linked to COPD. The disease progresses from chronic bronchitis (inflammation of the major airways) to emphysema (in which the lungs are heavily pitted).

People with advanced COPD often require inhaled corticosteroids (steroids) to reduce and control lung inflammation.


A chest injury or infection can lead to a condition called costochondritis in which the cartilage that joins your rib bone to your breastbone becomes inflamed. Costochondritis causes sharp or stinging pain and pressure on the chest wall.

Autoimmune Diseases

Lupus, rheumatoid arthritis, sarcoidosis, and scleroderma are all autoimmune diseases in which the body's own immune systems attacks healthy cells and tissues. Each of these diseases can directly or indirectly affect the lung and trigger lung inflammation. All autoimmune diseases are inflammatory.

Autoimmune diseases affecting the lungs can lead to Interstitial lung disease (ILD). ILD affects tissues around the airways, causing progressive scarring (fibrosis). The scarring causes the lungs to stiffen and makes it harder to breathe. Lung damage from ILD is often irreversible and gets worse over time.


Any type of trauma to the lungs or chest wall can cause acute pneumonitis. These include injuries like a rib fracture, a puncture wound, or a collapsed lung (pneumothorax) following a car accident.

People who suffer severe chest or lung trauma are vulnerable to pneumonia due to the build-up of fluid in or around the lungs. Penetrating wounds also allow bacteria to enter the chest wall, leading to a potentially severe infection.

Cystic Fibrosis

Cystic fibrosis CF) is a progressive genetic disease that affects the lungs, pancreas, and other organs. CF causes the excess build-up of mucus in the lungs, making it harder to breathe.

While CF isn't primarily an inflammatory disease, the blockage of the airways can trigger severe inflammation, particularly as the disease worsens.


Pericarditis is an inflammation of the sac (pericardium) that surrounds the heart. Pericarditis can be caused by an infection, heart attack, certain diseases, and even some medical treatments.

While pericarditis directly affects the lining of the heart, the inflammation can spread to the lungs, particularly if the underlying cause is severe or chronic.

Pulmonary Embolism

Pulmonary embolism (PE) occurs when a blood clot (embolus) gets stuck in the artery of the lung. The clot often develops in the lower extremities due to a condition called deep vein thrombosis (DVT). When a clot in the artery of the leg is dislodged, it can travel to the lungs and cause PE.

Large clots can cause severe chest pain and other overt symptoms. Smaller clots may be less noticeable at first but still cause significant damage due to the loss of oxygen in the surrounding tissues. The damage can be worsened by high levels of inflammation at the site of the obstruction.

Lung Cancer

Lung cancer is characterized by chronic lung inflammation as the immune system launches an assault again the cancerous tumor.

Pneumonitis is also a common side effect of cancer treatments, including radiation, chemotherapy, and newer targeted drugs and immunotherapies. All of these treatments trigger an inflammatory response as they target cancer cells for destruction.

How Is Lung Inflammation Diagnosed?

The causes of lung inflammation are many and require no less than a physical exam (including a check of breath sounds) and a review of your medical and family. Based on the findings, other tests and procedures may be ordered.

These include lab tests like:

  • Complete blood count (CBC): A blood test that can detect the presence of infection
  • Erythrocyte sedimentation rate (ESR): A blood test that detects generalized inflammation
  • C-reactive protein (CRP): Another blood test that detects generalized inflammation
  • Arterial blood gas (ABG): A blood test that measures the balance of oxygen and carbon dioxide in your blood to see how well your lungs are working

Procedures your doctor may order include:

  • Pulse oximeter: A device placed on the finger that can tell how saturated oxygen is in your blood
  • Pulmonary function tests (PFTs): A battery of tests involving devices you breathe into that measure the volume and strength of your lungs
  • Electrocardiogram (ECG): A non-invasive test that measures the electrical activity of the heart
  • Bronchoscopy: A procedure in which a narrow scope is passed through your nose or mouth and into your lungs to view the airways
  • Lung biopsy: A procedure in which a sample of lung tissue is removed with a needle or scalpel to view the airways

Imaging tests may include:

  • Chest X-ray: An imaging test that creates black-and-white images with low-dose ionizing radiation
  • Computed tomography (CT): An imaging test that composites multiple X-ray images to create 3-D "slices" of the lungs
  • Magnetic resonance imaging (MRI): An imaging test that used powerful magnetic and radio waves to create highly detailed images of soft tissues
  • Echocardiogram: An imaging test that evaluates how well the heart's chambers and valves are working using reflected sound waves
  • Ventilation-perfusion scan: An imaging test traces the flow of air and blood through your lungs

How Lung Inflammation Is Treated

The treatment of pneumonitis depends on the cause. For lung inflammation due to viral infections, such as the cold or flu, time and supportive care are all that is really involved. Pneumonitis due to other types of infection, such as Tb, will usually resolve once the underlying infection is treated.

Other causes may need treatments specific to pneumonitis to bring the inflammation under control.

Urgent Care

If you're having a breathing emergency, you may need oxygen therapy to bring your arterial blood gasses bad to normal In severe care, respiratory support may be needed to help you breathe. This support could include mechanical ventilation with intubation. This is when a tube is fed into the mouth and down the throat to deliver oxygen under controlled pressure.


Different medications may be used to alleviate lung inflammation either directly or indirectly. These include

  • Antibiotics: Used to treat bacterial lung infections
  • Antivirals: Sometimes used to treat viral infections (like Paxlovid for COVID-19)
  • Antifungals: Given by mouth or intravenously (into a vein) to treat fungal lung infections
  • Antihistamines: Used to relieve inflammation due to allergy or atopic diseases
  • Inhaled corticosteroids (steroids): Often used to control lung inflammation in people with asthma or COPD
  • Oral corticosteroids: Including drugs like prednisone intended for short-term use of acute inflammation
  • Biologic drugs: Including drugs like Humira (adalimumab) that suppress parts of the immune system to treat different types of autoimmune diseases

Procedures and Surgery

Home oxygen therapy may be indicated for chronic lung conditions that severely restrict oxygen blood saturation. It involves a portable oxygen tank and thin tubing (called a cannula) that delivers oxygen into your nostrils.

Surgery may sometimes be needed to remove an area of the lung that has been damaged by disease. Generally, lung cancer surgery involves removing a lobe of a lung or sometimes an entire lung to ensure the tumor and any cancer cells are extracted. Surgery for COPD entails removing damaged areas of the lung to improve airflow.


Lung inflammation (pneumonitis) may be due to infection, disease, injury, or exposure to environmental toxins or irritants. Lung inflammation can make it harder to breathe. Over time, if the inflammation doesn't improve, it can damage your lungs.

The diagnosis of pneumonitis may involve a review of your medical history, a physical exam, blood test, imaging tests, and procedures to measure how well your lungs and heart are working.

The treatment is typically focused on treating the underlying cause. If needed, oral or inhaled steroids can help temper the inflammation, while oxygen therapy can help if you have trouble breathing. Surgery is needed in some cases.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.