Take a clorox bath. Fill tub with as hot water as you can sit comfortable in. Add 1/2 cup of clorox. Soak in water until the water becomes cool, then drain tub. Follow bath with a hot shower and use plenty of soap to help remove the clorox smell and rinse well. Follow this with a cold shower. The hot soak will open the pores of your skin allowing the clorox bleach to flush the allergins from the skin surface, the hot shower with soap keeps the pores open and rinses the posions from the skin surface. The cold shower closes the pores. Relief can be felt by the next morning and the rash will start dryingup and the itching relieved.
This method worked for me as a kid, for my kids, and my grandkids. Everybody I have told this about claims it has worked for them. All I can say is give it a try. Currently, I am not affected by PosionIvy or Posion oak exposure. I can rub it on me and not get a rash. I dont however temp faith or make it a regular habit of running thru the stuff barefooted.