Pulmonary fibrosis is a condition that causes lung scarring and stiffness. It develops when the alveoli, tiny air sacs that transfer oxygen to the blood, become damaged and inflamed. Body tries to heal the damage with scars, but these scars collapse the alveoli and make the lungs less elastic. Changes in the lungs can also increase the blood pressure in the pulmonary artery.
Many people diagnosed with pulmonary fibrosis are initially treated with a corticosteroid (prednisone), sometimes in combination with other drugs that suppress the immune system such as methotrexate or cyclosporine. Adding acetylcysteine, a derivative of a natural amino acid, to prednisone may slow the disease in some people. None of these combinations has proved very effective over the long run.