Cortisol, can someone list both the positive & negative effects it can have on the body.

Depends on source: Cortisol produced by the body is not harmful, unless there is a tumor producing excessive amounts of it. Cortisol is needed to maintain normal circulation and electrolytes and body mass, among other things. If a tumor produces too much, or if it's obtained in higher amounts from an external source, then it causes bone loss, obesity, acne, infections, psychiatric problems, and more.