|I suffered thru a childhood plauged by poison ivy until I learned that $2 worth of mechanics soap could simply wash it away!
The best that I found is made by Lava and GoGo. You can pick up a 16 oz bottle at any auto parts store or walmart...
You simple apply it to dry skin without any added water and scrub for ~ 2 minutes then wash it away with cold water. It breaks the stickiness of the oil down and gives you time to wash it right off. Also works well at removing it from your clothes.
I like the Lava and GoGo the best because it is gritty and works faster than some others I have tried. I'm sure most will work.