There is new stuff to help with poison ivy. It is called Technu. If you wash within a few hours of exposure this will remove all the urushiol and keep you from developing symptoms.
Oddly enough Techu was originally developed to cleanse nuclear contamination. But boy does it work great on poison ivy. If I wash after weed eating, I may get one or two small bumps versus all up and down my arms if I do not wash.
Their Technu Extreme product is designed for when you are already displaying symptoms.
There are other products on the market based on the same technology, but I still prefer Technu.