Pneumonitis (noo-moe-NIE-tis) is a general term that refers to inflammation of lung tissue. Although pneumonia is technically a type of pneumonitis because the infection causes inflammation, most doctors are referring to other causes of lung inflammation when they use the term “pneumonitis.”
Factors that can cause pneumonitis include exposure to airborne irritants at your job or from your hobbies. In addition, some types of cancer treatments and dozens of drugs can cause pneumonitis.
Difficulty breathing — often accompanied by a dry (nonproductive) cough — is the most common symptom of pneumonitis. Specialized tests are necessary to make a diagnosis. Treatment focuses on avoiding irritants and reducing inflammation.
Pneumonitis occurs when an irritating substance causes the tiny air sacs (alveoli) in your lungs to become inflamed. This inflammation makes it difficult for oxygen to pass through the alveoli into the bloodstream.
Many irritants, ranging from airborne molds to chemotherapy drugs, have been linked to pneumonitis. But for most people, the specific substance causing the inflammation is never identified. Pneumonitis causes may include:
- Drugs. A variety of drugs can cause pneumonitis, including some antibiotics, several types of chemotherapy drugs and medications that keep your heartbeat regular. An overdose of aspirin can cause pneumonitis.
- Molds and bacteria. Repeated exposure to some molds and bacteria can cause the lungs to become inflamed. Specific varieties of mold-related pneumonitis have received nicknames, such as “farmer’s lung” or “hot tub lung.”
- Birds. Exposure to feathers or bird excrement is a common cause of pneumonitis.
- Radiation treatments. Some people who undergo radiation therapy to the chest, such as for breast or lung cancer, may develop pneumonitis. Pneumonitis also can occur after whole-body radiation therapy, which is needed to prepare a person for a bone marrow transplant.
The most common symptom of pneumonitis is shortness of breath, which may be accompanied by a dry cough. If pneumonitis is undetected or left untreated, you may gradually develop chronic pneumonitis, which can result in scarring (fibrosis) in the lungs.
Signs and symptoms of chronic pneumonitis include:
- Shortness of breath
- Loss of appetite
- Unintentional weight loss
When to call a doctor
Call your doctor anytime you have difficulty breathing, no matter what might be the cause.