Prednisone is used in many illnesses for its anti-inflammatory benefits.
I have had cortisol levels explained this way:
Once you start taking prednisone (a dosage larger than 7mg), your own adrenal gland stops producing cortisol and it is the prednisone basically taking over.
As you reduce the prednisone - the adrenal glands will begin working again.
I have taken prednisone on and off for many years for asthma/bronchitis
I have just been diagnosed with Ulcerative Colitis and am back on it again
It is a powerful medicine that can be life saving for many people.
On the flip side - it has many side effects - some which are tolerable others that aren't