Many physicians who utilize hydrocortisone as a treatment for adrenal dysregulation (low cortisol states) refer to William Jeffries' "Safe Uses of Cortisol" to explain its use. I am wondering, is there any actual published that physiological doses around 20mg is safe for long term use (does Jeffries have citations in his book supporting this)? I am wondering since I am suffering from chronic fatigue/low cortisol/cognitive dysfunction/exercise intolerance. My doctor decided to prescribe me 20mg HC per day, and while it has helped me, I'm not totally convinced that this is the way to go. As I understand (from reading forums and also Dr. Mariano's posts on his forum), there are reasons for HPA axis downregulation - perhaps neurochemical or immunological. It would be better to figure out why cortisol output is low rather than supplementing HC (but it also seems rather difficult to determine the cause since so many people are still suffering with this).