Some of you may have heard of this one. It worked great for me when I was a kid. I used to get Poison Ivy, Oak and or Sumac all the time and I had it bad to the point my legs would blister and weep. My grandfather recommended this. Take a sock and put about two or three cups of oatmeal in it. Run it under warm water and knead it a little. Once wet, squeeze out the excess water. Once the extra water is gone, you'll get this slimy white extract from the oatmeal. Rub this over your poison as you would calamine lotion. I would keep a small bowl of water close in case the sock and oatmeal became too dry. Let it dry over your rash. Reuse as the itch comes back.
It takes away the itch and dries out the poison in just a few days, and that was in my extreme cases. You may need a refill of oatmeal if all the slime (I think it's starch) is gone. But one good sock full usually lasted me for the few days I needed it. I hope this helps those who get the rashes. I don't get it that bad any more. I remembered this tip after finding a few dots of rash on my lower when ever I’m in those areas with Poison Ivy!