I am HIGHLY allergice to poison ivy. I get it every year, and stopped going in the woods altogether a long while ago. Even with tights, socks, boots, and everything tucked in together, I still get it just by being out of doors. The first year I got it bad I had to go to the doctors and get on steroids. It's bad. However, in a fifth grade science book I came across the treatment, but didn't test it until years later. I wish I had listened sooner, and I urge anyone who does get poison ivy to take heed.
Here's what you do: When the itching gets bad, go into the shower. Turn it on HOT, and then direct the spray to the affected area(s). Slowly turn up the heat. This will finally hit that "itch" where it lives and will be about the most pleasurable experience of your life. It's endorphines like no other. Eventually the relief will turn to numbness, and this is when the magic occurs. Turn off the water, get out, and you'll find that the place previously burning with misery is numb and will stay that way for hours. If it begins itching again, jump back in the shower. There were times when I took up to four showers a night in order to sleep, but it worked. This will treat, but it also shortens the lifespan of the whole encounter. The patches are being drained of their poison and the skin gets dry.
Whatever you do, do NOT take a hot bath. This will put the poison in the water and then it will spread everywhere. Look to the hot shower, and all will be well. Trust me!