There are several reasons why the lungs may start scarring, but in many cases the cause is unknown (idiopathic). However, smoking and exposure to a poor atmosphere in the workplace are often leading causes.
Patients usually require a constant supply of oxygen as they become unable to extract sufficient oxygen from air. However, the constant supply of oxygen usually has the side effect of damaging the lungs further. As such, most patients have to be given steroids (usually in aerosol form) to reduce inflammation and open the bronchial tubes. However, patients gradually adjust to the drugs and require higher doses to get the same effect.
Prednisone is the steroid of last resort as although it is incredibly effective, it has drastic side effects including immunosuppression. In addition, once a patient is on prednisone, they cannot be taken off the drug without the symptoms rebounding, causing life-threatening bronchial constriction.