Pneumonitis vs. pneumonia

Both pneumonitis and pneumonia are terms used to describe inflammation in your lungs. In fact, pneumonia is one type of pneumonitis. If your doctor diagnoses you with pneumonitis, they’re usually referring to inflammatory lung conditions other than pneumonia.

Pneumonia is an infection caused by bacteria and other germs. Pneumonitis is a type of allergic reaction. It happens when a substance like mold or bacteria irritates the air sacs in your lungs. People who are especially sensitive to these substances will have a reaction. Pneumonitis is also called hypersensitivity pneumonitis.

Pneumonitis is treatable. However, it can cause permanent scarring and lung damage if you don’t catch it early enough.

The first symptoms will usually appear within four to six hours after you breathe in the irritating substance. This is called acute pneumonitis. You might feel like you have the flu or another respiratory illness, with symptoms like:

  • fever
  • chills
  • muscle or joint pain
  • headache

If you’re not exposed to the substance again, your symptoms should go away within a few days. If you continue to be exposed, you can develop chronic pneumonitis, which is a more long-term condition. About 5 percent of people with pneumonitis will develop the chronic form.

Symptoms of chronic pneumonitis include:

  • dry cough
  • tightness in your chest
  • tiredness
  • appetite loss
  • unintentional weight loss

You can get pneumonitis when substances you breathe in irritate the small air sacs, called alveoli, in your lungs. When you’re exposed to one of these substances, your immune system reacts by producing inflammation. Your air sacs fill with white blood cells and sometimes fluid. The inflammation makes it harder for oxygen to pass through the alveoli into your bloodstream.

Substances that can trigger pneumonitis include:

  • mold
  • bacteria
  • fungi
  • chemicals

You’ll find these substances in:

  • animal fur
  • bird feathers or droppings
  • contaminated cheese, grapes, barley, and other foods
  • wood dust
  • hot tubs
  • humidifiers

Other causes of pneumonitis include:

  • certain medicines, including some antibiotics, chemotherapy drugs, and heart rhythm medicines
  • radiation treatment to the chest

You’re at higher risk for pneumonitis if you work in an industry where you’re exposed to dust that contains irritating substances. For example, farmers are often exposed to grain, straw, and hay that contains mold. When pneumonitis affects farmers, it’s sometimes called farmer’s lung.

Another risk is exposure to mold that can grow in hot tubs, humidifiers, air conditioners, and heating systems. This is called hot tub lung or humidifier lung.

People in the following professions are also at risk for pneumonitis:

  • bird and poultry handlers
  • veterinary workers
  • animal breeders
  • grain and flour processors
  • lumber millers
  • woodworkers
  • wine makers
  • plastic manufacturers
  • electronics

Even if you don’t work in one of these industries, you can be exposed to mold and other triggering substances in your home.

Being exposed to one of these substances doesn’t mean you’ll definitely get pneumonitis. Most people who are exposed never get this condition.

Your genes play an important role in triggering your reaction. People with a family history of pneumonitis are more likely to develop the condition.

You can get pneumonitis at any age, including childhood. However, it’s most often diagnosed in people ages 50 to 55.

Cancer treatments can also increase your chance of getting pneumonitis. People who take certain chemotherapy drugs or who get radiation to the chest are at greater risk.

See your doctor if you have symptoms of pneumonitis, especially shortness of breath. The sooner you start avoiding your trigger, the more likely you’ll be to reverse this condition.

To see if you have pneumonitis, visit your primary care doctor or a pulmonologist. A pulmonologist is a specialist who treats lung diseases. Your doctor will ask what substances you might have been exposed to at work or home. They’ll then do an exam.

During the exam, your doctor listens to your lungs with a stethoscope. They might hear a crackling or other abnormal sounds in your lungs.

You may have one or more of these tests to find out if you have pneumonitis:

  • Oximetry uses a device placed on your finger to measure the amount of oxygen in your blood.
  • Blood tests can identify antibodies in your blood against dust, mold, or other substances. They can also show if you’re having an immune system reaction.
  • A chest X-ray creates pictures of your lungs to help your doctor find scarring and damage.
  • A CT scantakes pictures of your lungs from many different angles. It can show damage to your lungs in more detail than an X-ray.
  • Spirometry measures the force of your airflow as you breathe in and out.
  • Bronchoscopy places a thin, flexible tube with a camera on one end into your lungs to remove cells for testing. Your doctor might also use water to flush cells out of your lungs. This is called lavage.
  • Lung biopsy is a procedure to remove a sample of tissue from your lung. It’s done while you’re asleep under general anesthesia. The tissue sample is tested for signs of scarring and inflammation.

Learn more: Allergy testing »

The best way to relieve your symptoms is to avoid the substance that triggered them. If you work around mold or bird feathers, you may need to change jobs or wear a mask.

The following treatments can relieve pneumonitis symptoms, but they won’t cure the disease:

  • Corticosteroids: Prednisone (Rayos) and other steroid drugs bring down inflammation in your lungs. Sidea effects include weight gain and an increased risk for infections, cataracts, and weakened bones (osteoporosis).
  • Oxygen therapy: If you’re very short of breath, you can breathe in oxygen through a mask or prongs in your nose.
  • Bronchodilators: These medicines relax the airways to help you breathe easier.

If your lung is so severely damaged that you can’t breathe well even with treatment, you may be a candidate for a lung transplant. You’ll have to wait on an organ transplant list for a matched donor.

Constant inflammation can cause scars to form in the air sacs of your lungs. These scars can make the air sacs too stiff to fully expand as you breathe. This is called pulmonary fibrosis.

In time, the scarring can permanently damage your lungs. Pulmonary fibrosis can also lead to heart failure and respiratory failure, which could be life threatening.

It’s important to get treated as soon as possible if you have pneumonitis. You’ll also want to identify and avoid the substances that triggered it. Once you have lung scarring, it’s not reversible, but if you catch pneumonitis early, you can stop and even reverse the condition.