Another product to use is "naptha soap". It's an old fashioned bar of soap that you can sometimes find in the laundry soap section of your grocery store. It's brown in color. The lye soap works to. I wash up with the "naptha soap" whenever I think I've been exposed and it seems to help.
Back when I did forestry and arborist work I got the worlds worst poison ivy exposure. I climbed and was taking down a tree that had a wrist thick poison ivy vine growing up it. I had on a face shield, long sleeves, gloves, bandana etc. (thought I was adequately protected) It turned out that the sawdust and chainsaw bar spray was hitting me in the forehead, went down my shirt, into my skivvies, down my pant legs and into my socks. Yep, you guessed it, I had poison ivy from head to toe (literally). You've never suffered with poison ivy, until you've had it on your johnson. Pure agony! The oral steroids mess me up bad, I just used calamine lotion (Liberally) and took coloidal oatmeal baths (helps it dry up).