Pneumonitis (noo-moe-NIE-tis) is a general term that refers to inflammation of lung tissue. Technically, pneumonia is a type of pneumonitis because the infection causes inflammation. Pneumonitis, however, is usually used by doctors to refer to noninfectious causes of lung inflammation.

Common causes of pneumonitis include 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.