Interstitial lung disease describes a large group of disorders, most of which cause progressive scarring of lung tissue. The scarring associated with interstitial lung disease eventually affects your ability to breathe and get enough oxygen into your bloodstream.
Pneumonitis 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.
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.
Source: MayoClinic.org
