Best thing you can do is go here and read:
Poison Ivy, Oak, and Sumac Information Center - (www.poisonivy.us)
I'm extremely allergic to the stuff, have been all my life. When I was a little kid and would get it, I learned to not scratch it.
What I do, and have done for years, is to run the hottest water I can stand on it. This pulls the histamins out of the cells. The histamins cause the itch. It will relieve the itch for several hours, and let the blisters come on up and start to weep. This is messy, but it means the stuff is going away.
The rash is the body's reaction to the urushiol oil in the poison ivy plant. It pentrates the skin in about 20 minutes after exposure. The body's immune system sees it as an invader and acts to repel it, thus the blisters.
Several years ago one of the cats must have brushed against some then came in the house and rubbed my legs. Almost overnight I had the WORST outbreak I could remember. It started on my left leg and spread all over my body. Scalp to feet. Face, arms, torso, legs. Horrrrrrrrrrible. ***If you can stand it, take a look at the pictures of some peoples outbreaks, that's the kind I had. It will make your skin crawl.....
Experience has taught me there's nothing to do but ride it out and use the hot water. I'd stand in the shower, using the handheld, and spray the hottest water I could stand on it. The relief it brings is unbelieveable. It pulls the itch out and you just want to yell it feels so good.
The oil spreads, and something like dish detergent can be used within the 20 minute time frame [if you know you have been exposed.] If you do not realize it and go without washing and rinsing, the outbreak will be worse. It is recommended by folks on the website linked that you stay in the shower with the water running for a long time, as the oil is hard to remove.
Any clothes, gloves, tools, that have come into contact with the oil will retain it for years and reinfect you the next time you handle them. They will have to be scruptiously cleaned or thrown away.
There's a wealth of information at the website, maybe something there will be of help to you.
Since that outbreak I had, I've Roundupped every bit of it I can find on my property.