I usually get poison ivy a couple of times a year. Hiking, hunting, riding ANYTHING out in the woods. i started to carry a small bottle of bleach in the car and a washcloth to wipe down with after my activities. Haven't had it since IF I remeber to bring the bleach!
Bleach (onced opened) looses its potency real quick. Buy the smallest bottle to suit your needs. (I do R&D for a major detergent company )
Jeni