1. Take a Cold Shower
The irritating discharge that poison oak, sumac and ivy produces is known as urushiol sap.
And if you have any reason to believe that you have been exposed to it on your foot travels, it is imperative to return home as quickly as possible and wash it off your skin using soap and cold water.
You will also need to wash your clothing and anything else that you had with you that came into contact with the applicable plant. This is due to the fact that you can actually get exposed again later on by touching something that has urushiol sap on it.
Flickr user Carlos Pacheco