KOTA News (ABC affiliate in Wyoming) offers readers a tip on their website for using vinegar if someone has poison ivy. The tip is noted below:
Mix a small amount of vinegar with enough baking soda to make a paste the consistency of peanut butter.
Stand in the shower to get wet all over. Turn off water. Put paste on wet washcloth and scrub it into your skin all over, scrubbing as hard as possible. Rinse off paste. Towel dry and then apply straight vinegar all over your body with a clean washcloth. Let dry.