Glycerin based Jewelweed soap works as both a preventative and as relief from poison ivy rash. 
 
Apply like a salve on exposed skin before venturing out and the oils act as a barrier binding with the urushiol in poison ivy to keep it from irritating your skin.  Wash off when you get home.  If you forget and have exposure, use this soap to wash the urushiol from your skin.
If a rash occurs, jewelweed can be helpful in accelerating healing time.
 
Ingredients: Olive oil glycerin soap base, fresh ground jewelweed leaf and flower, fresh calendula flowers, and fresh plantain leaves.
 
2oz bar