|Use Tecnu. It's amazing at removing the oils that cause poison ivy. Use it anytime you might have been in contact with poison ivy, oak or sumac. It really helps with the itch and to keep it from spreading. There is a whole page devoted to it on the web site. I am highly allergic and have been using it for 10 years. Prior to discovering it from a friend, every time I had a break out they always lasted 4 weeks.
It also removes jalepeno oils from my hands when I have been cutting them up.