I think the length of time that it lasts is in some way related to how sensitive a given person is to the plant. Myself, I've had poison ivy a while back and my most recent affliction appears (or at least the doctors say it is) poison oak. Fun. I've had it for nearly a week and a half now and have had at least two shots and am now taking the prednizone and am using a topical cortical steroid. It might not necessarily be what works for everyone, but I've finally got my left arm back down to at least approaching normal size and managed to stop my right arm from swelling to match.
I swear..this stuff is so nerve-wracking instead of signs reading "Beware of Dog" or "Trespassers will be shot on sight" I'll just get a few signs that say "Professional Poison Oak Cultivator Lives Here"...on second thought, I don't want to get shot..LOL
