"A wise old man told me that the water in a quench bucket (which is the bucket a blacksmith uses to cool iron rapidly by dunking the hot iron in it) was the best cure-all for poison ivy that he had ever used. When a friend came down with a bad case of poison ivy and told me that calamine lotion wasn't working, I shared the wise man's story. She promptly filled a plastic spray bottle with my dirty quench water and coated her arms and legs. A day later she returned to the shop wanting to sell the "magic elixir" to the public. The theory? Heavy concentrations of iron in the water accelerated the drying up of poison ivy blisters." 
I have not been allergic to poison Ivy my whole life. In my thirties I was helping a friend pull poison ivy in the late fall. The foliage had dried up and we were pulling it by the roots. Not thinking the oil was drained down in the roots concentrated in storage till next Spring & highly concentrated in the roots we were pulling. 2 days later I was a mess. Both arms a runny bubbly rash & my face was so swollen my eyes were slits, my nose was just 2 holes no protrusion for the nose, and my mouth just a slit & I just sipped Carnation Breakfast & Slim Fast for 3 days through a straw. My doctor gave me some sort of antihistamine tablet & the only other thing I put on the poison ivy was Sweet Fern, which we have masses of here. I was told to stay quiet, and I just laid in bed (watching TV) with poultice of sweet fern on my arms, face, & neck down a little on my upper chest. In a big pot I simmered the sweet fern to limp it & I was draped in the soggy weeds 24 hours a day. I also drank the juice as a tea to work from the inside out. This is an old natural remedy around here for sunburn, poison weed rashes, and other skin inflammations. I pulled the ivy on Sunday, forced to leave work early on Tuesday with the rash. On Saturday my face which only swelled, no oozing rash like the rest of the affected skin, was totally normal. I was told by the Doctor there are three ways poison ivy can affected human skin & I had 2, one on my swollen face & the oozing bubbly rash on the rest of the affected skin. I went back to work Monday with hardly any signs of rash. Sweet fern, you can Google it, was a miracle worker for me. After that I would get a slight, very slight rash between my fingers, that cleared up 2 day later, if I messed with poison ivy. Now I am not bothered with with it at all. What a miserable mess I was, and sweet fern was my hero.
The best defence and cure for poison ivy is, of course, to avoid it, so learn how to recognize the plants and be aware that they can grow as vines or shrubs. They can be spotted by their characteristic cluster of three pointed leaves. The leaves are shiny and the berries are green/yellow in color. Recognition is of particular importance for those people who love to be out in the countryside, camping and hiking. As a regular camper and hiker, you should already know that going into the great outdoors makes you fair game for a myriad of stinging insects as well as noxious plants like the poison ivy. If you are uncertain as to whether you will come across the plant or not, wear protective clothing, and if you are caught off guard, try to rinse off the affected area as quickly as possible to rid yourself of the plant’s toxic resin.