I developed a rash on my arms/chest/face since last November when I was first put on Prednisone. At first drs thought it was a reaction to Plavix, but rash continued after they took me off it. I didn't seem to have any issues (rash cleared up) while in the hospital for a week in February and on IV prednisone. Could it be that a person can have an allergic reaction to the oral and not the IV form? How long before the rash goes away after quitting it?