We have poison oak out here, but it does the same thing. All I have to do is look at it, to get it. If I get exposed I start feeling it almost immediately. I hate the stuff. I fought wild fires for about 7 years and would get it 10 or 15 times a year out on the line. Been hospitalize several times with it. Get it enough you build a tolerance for the season.
Anyway I've tryed everything(except that jewelweed), laundry soap seemed to help some, bleach helped a little, but these days if I'm exposed I go straight to the doctor and get a shot of prednisone. It'll start getting better with in hours. Why suffer. Get the shot.