Nature's remedy for poison ivy
"Special Note: For on-the-trail treatment and prevention you can't beat nature's own remedy, jewelweed. The Native Americans used Jewelweed. It is usually found in moist, shaded areas and is identified by it's waxy leaves. After a rain or heavy dew, water beads up on the waxy leaves and looks like jewels. It's almost always found close to ivy, so it's usually availible when you need it. Crush a few leaves and stems and rub them on your skin, or crush and soak in water for a larger amount. You can also put a mess of jewelweed in a large glass container and make a "sun tea" out of it to use as a compress (not to be taken internally) to help soothe the eruption if it develops."
Here is a link that might be useful: Jewelweed image