A "friend" accidently wiped, using of all things, two poisen ivy leaves. Long story short, my "friend" was in a really bad way. (I'd be laughing hard right now, if I didn't see the rash for myself first hand)
It took us two days of driving, but we got there.
We brought him/her to the beach and had them soak in the ocean water for a half hour.
Tada! No more poisen ivy! It was completely healed the next day.
I stumbled on this trick as a child, when I got some on my hand. I went swimming in the ocean and noticed it cleared up miraculously the next day.
I pass this along in case this happens to someone you love!