Health Information Library

Overview

Pneumonitis (noo-moe-NIE-tis) is a general term that refers to swelling and irritation, also called inflammation, of lung tissue. Lung infections such as pneumonia also can cause lung tissue to become inflamed. But pneumonitis generally refers to inflamed lung tissue not caused by an infection.

Pneumonitis is a result of an extra strong defense response by the body's immune system to an irritating substance. Common causes of pneumonitis include airborne irritants at a job, in the home or from hobbies. Other causes include some cancer treatments and many different medicines.

Trouble breathing, and often a dry cough, are the most common symptoms of pneumonitis. Treatment focuses on avoiding irritants and lessening the inflammation of lung tissue.

Symptoms

Symptoms of pneumonitis may develop quickly or slowly and can worsen over time. At times symptoms may suddenly get worse or better. Also, symptoms vary greatly among people with the condition and include:

• Trouble breathing.
• Dry cough that usually doesn't bring up any mucus.
• Extreme tiredness.
• Loss of appetite.
• Fever.
• Joint and muscle pain.
• Headache.
• Weight loss.

When to call a doctor

Talk to your doctor or other healthcare professional if you notice symptoms such as trouble catching your breath or an ongoing dry cough.

If you have trouble breathing, go to the emergency department at a hospital right away or, in the U.S., call 911.

Causes

Pneumonitis happens when an irritating substance causes inflammation in the tiny air sacs called alveoli in your lungs. Inflamed lung tissue makes it hard for oxygen to pass through the alveoli into the bloodstream.

Many causes have been linked to pneumonitis. But it's not clear why some people have a strong immune system response to certain substances that cause pneumonitis, while others do not. For many people, the specific substance causing the inflammation is never identified.

Some types of pneumonitis include hypersensitivity pneumonitis, drug-induced pneumonitis and radiation-induced pneumonitis.

Hypersensitivity pneumonitis

For some people, breathing in airborne particles triggers a strong allergic reaction by their immune system. This reaction irritates the lungs, causing pneumonitis. The condition also is called extrinsic allergic alveolitis.

Specific types of hypersensitivity pneumonitis have nicknames related to their cause, such as "farmer's lung," "bird-fancier's lung" or "hot tub lung."

Causes can include:

• Molds. Repeated exposure to molds can cause inflamed lung tissue. Breathing in airborne bits from moldy hay is one of the most common causes of work-related pneumonitis. Moldy conditions in hot tubs also can cause pneumonitis because the bubbling action makes a mist containing mold. It's common for mold to grow in home humidifiers that aren't cleaned often. Other examples of humid places where mold can grow and be released into the air include air conditioners, swimming pools, water-damaged carpet and ventilations systems.
• Birds. Exposure to bird feathers, dust or droppings is a common cause of pneumonitis.
• Dust. Exposure to dust from metal work or hardwoods can cause pneumonitis.
• Chemicals. Aerosolized mists, chemicals and pesticides can irritate lungs and cause pneumonitis.
• Animal fur. Skin cells, fur and droppings from animals are another cause of pneumonitis. This may happen when working closely with cattle and in veterinary practices.

Drug-induced pneumonitis

Many medicines can cause pneumonitis. But the exact reason why certain medicines cause inflamed lung tissue isn't clear. It's possible that some medicines may irritate lung cells, and then the immune system has a strong response that causes inflammation.

Examples of medicines that may cause pneumonitis include certain antibiotics, many medicines used to treat cancer and some medicines that keep your heartbeat regular.

Radiation-induced pneumonitis

Some people who have radiation therapy to the chest, such as for breast or lung cancer, may get pneumonitis. Pneumonitis also can happen after whole-body radiation therapy that's done to prepare a person for a bone marrow transplant. Symptoms usually appear in the first few months after radiation treatment is finished.

Risk factors

Environment

Some factors cause a higher risk of pneumonitis, including:

• Jobs and hobbies. Farming raises exposure to mold particles that can be breathed in during harvests of grain and hay. Another risk factor is a job where workers are around fine mists, fumes, dust and chemicals. Woodworking may raise your risk too.
• Bird and animal handling. Poultry workers and people who breed or keep pigeons and other birds often are exposed to droppings, feathers and other materials that can cause pneumonitis. Being around a lot of animals also may raise your risk.
• Using hot tubs and humidifiers. Moldy conditions in hot tubs, home humidifiers that aren't cleaned often and anywhere else mold can grow are risk factors for pneumonitis.

Cancer treatment

Some medicines used to treat cancer can cause pneumonitis. So can radiation therapy to the lungs and chest. The combination of the two raises the risk of pneumonitis even more.

Genes

Genes may play a role in having an extra strong immune response to substances. If you have family members who have a strong allergic reaction to substances, you may have a higher risk of an allergic reaction as well.

Complications

If pneumonitis is not detected or not treated, you may gradually develop lung damage that can't be reversed.

In healthy lungs, the air sacs stretch and relax with each breath. Ongoing inflammation of the thin tissue lining each air sac causes scarring and makes the air sacs less flexible. They become stiff like a dried sponge. This is called pulmonary fibrosis. In severe cases, pulmonary fibrosis can cause high blood pressure in the lungs, right-sided heart failure, respiratory failure or death.

Diagnosis

To diagnose pneumonitis, your doctor or other healthcare professional reviews your medical history and family history. You talk about your symptoms and review any medicines you take and previous treatments such as cancer treatment that you've had. You also will likely be asked about any ongoing or repeated contact with dusts, chemicals, birds and mold sources, especially through home, work or hobbies.

The healthcare professional does a physical exam and uses a stethoscope to listen to your lungs while you breathe.

One option to help diagnose hypersensitivity pneumonitis is to avoid the suspected environmental substance for several weeks to see if symptoms get better.

To tell pneumonitis from other lung conditions, you'll likely have one or more tests.

Blood tests

Certain blood tests can be useful to pinpoint a diagnosis. For example, a blood test may be able to tell if you have an infection. Blood tests can check for antibodies that suggest exposure to an allergen. Another blood test, called an arterial blood gas, can measure the oxygen and carbon dioxide levels in the sample.

Imaging tests

• Chest X-ray. Images of your lungs can give an idea of where and how severe the inflammation is. An X-ray also may rule out other conditions that are causing your symptoms, such as pneumonia. Sometimes an X-ray may not show any changes.
• Computerized tomography (CT). A CT scan combines X-ray images taken from many different angles to create images of structures inside the body. A CT scan gives much greater detail of changes in your lungs than a chest X-ray can show. A CT scan also can be helpful in finding out how much lung damage has occurred.

Pulmonary function tests

Pulmonary function tests are done to find out how well your lungs are working:

• Spirometry. In this test, you breathe out quickly and forcefully through a tube connected to a machine. The machine measures how much air the lungs can hold and how quickly air moves in and out of the lungs.
• Lung volume test. This test measures the amount of air the lungs hold at different times when breathing in and out.
• Lung diffusion test. This test shows how well the body moves oxygen and carbon dioxide between the lungs and the blood.
• Pulse oximetry. This simple test uses a small device placed on one of the fingers to measure how much oxygen is in the blood. The percentage of oxygen in the blood is called oxygen saturation. Your healthcare professional may recommend a six-minute walking test with a check of your oxygen saturation.

Imaging and lung function tests also can be used to check your condition over time and see how treatments are working.

Bronchoscopy

A bronchoscopy is a procedure to look at your lungs and air passages. A thin tube called a bronchoscope is passed through your nose or mouth, down your throat and into your lungs.

Your doctor may flush a section of your lung with a saltwater solution to collect lung cells and other materials. This flushing procedure is known as a lavage.

Your doctor also may remove very small tissue samples from your lungs. The tissue samples are sometimes too small to make the right diagnosis. But this form of biopsy also may be used to rule out other conditions.

Surgical lung biopsy

Your doctor may want to examine larger samples of tissue from several sites in your lungs that can't be reached using bronchoscopy. A surgical procedure to collect these samples may be needed. Although a surgical biopsy is invasive and has a risk of complications, it may be the only way to make the right diagnosis. This procedure may be done as a minimally invasive surgery.

Treatment

Treatment may depend on the cause of pneumonitis.

Hypersensitivity pneumonitis

If you have pneumonitis caused by chemical irritation or an allergic reaction, your healthcare professional will likely recommend stopping the exposure that's irritating your lungs. This step should help lessen your symptoms.

Ways you can lower exposure include:

• Avoiding the triggering substance, if known. This may even mean choosing a different job or hobby if your condition is severe.
• Wearing protective gear. Face protection that filters out particles, such as a pollen mask or a personal dust respirator, may lessen exposure.
• Improving ventilation. Better airflow in the area with the substance causing your symptoms may lessen your exposure.
• Limiting mold growth. Cleaning places mold can grow, such as in hot tubs, ventilation systems and humidifiers, may avoid exposure. Remove water-damaged carpet, furniture and drywall.

Corticosteroid medicines work by calming your immune system's reaction to an irritation. This can make your lungs less inflamed. Corticosteroids are usually taken as a pill for a limited time. Long-term corticosteroid use raises your risk of developing infections and is linked with thinning of bones called osteoporosis. Other medicines that lessen your immune system's response may be used.

Sometimes corticosteroids using an inhaler may help. You breathe these medicines into your lungs. The medicines lessen inflammation in your airway so that it's easier to breathe.

Bronchodilators are medicines that also usually come in inhalers. These medicines relax the muscles around your airways. This can help relieve coughing and make breathing easier.

Drug-induced pneumonitis

Treatment for pneumonitis caused by medicines depends on how severe symptoms are. If symptoms are mild, you may not need any treatment. If your symptoms are severe, treatment with mainly corticosteroids, but sometimes other medicines that lessen your immune system's reaction, may help. Sometimes your healthcare professional may decide to stop or change medicines that are causing the inflammation.

Radiation-induced pneumonitis

If symptoms are mild, you may not need treatment for radiation pneumonitis. Severe symptoms are usually treated with corticosteroids.

Treatment options for any cause of pneumonitis

When pneumonitis is severe, treatment also may include:

• Oxygen therapy. If you're having a lot of trouble breathing, you may need oxygen therapy through a mask or through a plastic tubing with tips that fit into your nose. You may use oxygen when you sleep or exercise. But some people need oxygen all the time. Carrying a small tank of oxygen or using a portable oxygen concentrator can help you be more mobile.
• Pulmonary rehabilitation. Pulmonary rehabilitation can help manage your symptoms and improve your ability to do daily tasks.
• Lung transplant. Severe lung damage may require a lung transplant.

Lifestyle and home remedies

A diagnosis of pneumonitis may mean that you'll have to make changes to your lifestyle to protect your health. You'll need to avoid known triggers as much as possible.

Don't smoke. Smoking can make lung damage worse. If you need help quitting, talk to your healthcare professional.

If your job duties expose you to substances that irritate your lungs, talk to your healthcare professional and supervisor at work about ways to protect yourself. If a hobby is causing the problem, you may have to find a different hobby.

Preparing for an appointment

You may start by seeing your family healthcare professional. You may then be referred to a doctor with expertise in lung conditions called a pulmonologist.

What you can do

Before your appointment, make a list that includes:

• Your symptoms, including when they began and if anything seems to make them worse or better.
• All jobs and any exposures that may be part of your work activities.
• Hobbies you regularly do that may expose you to substances that could irritate your lungs.
• Medical problems you've had and their treatments.
• Medical problems of your parents or siblings.
• All medicines, vitamins, herbs and supplements you take or have taken in the last few years. Include the doses.
• Questions to ask your healthcare professional.

Questions to ask may include:

• What is likely causing my symptoms?
• What kinds of tests do I need?
• What treatment do you recommend?
• I have other health conditions. How will my pneumonitis affect them?
• Are there any restrictions that I need to follow?

Feel free to ask other questions during your appointment.

What to expect from your doctor

Your healthcare professional may ask you questions such as:

• Do you now or have you ever smoked tobacco?
• What types of jobs or hobbies have you had?
• Do your breathing symptoms get worse or better related to your work or hobby schedules?
• Do you have a hot tub or humidifier at home?
• Are you ever around pigeons or pet birds?

Be ready to answer questions so that you have time to talk about what is most important to you.