Just now saw this post!
I've had poison ivy several times and I can never git rid of it without going to the doctor, it just keeps spreading on me.
Usually I get the shot mentioned above and a prescription for some type of steroid pill if I remember right the name of it was methylprednisolone, not sure about the spelling.
You take it for 7 days, a couple less pills each day. That stuff cranks me up like you wouldn't believe!!! For the first few days your supposed to take about 7 pills I think, I can't be still at all, can't sleep and night or anything! That stuff would be great to have on a tough high country hunt.