Pulmonary fibrosis is a condition characterized by gradual scarring of your lung tissue. Over time, your lung tissue thickens, making it difficult for your organs to reap necessary oxygen. Common symptoms of pulmonary fibrosis include coughing, fatigue, lethargy and loss of appetite.

Interstitial lung disease, ILD or pulmonary fibrosis, includes more than 200 chronic disorders of the lungs, according to the University of Chicago Medical Center. The term applies to scarring of the tissue in the lungs surrounding the air sacs.