freelastchance
I have never had poision ivy, and I've never heard anything about the peppermint oil, but the cold effect it gives the skin would probably be soathing.
My best friend had poision oak really bad one time, and after about a week it was still pussy etc, and she started putting
Colloidal Silver on it - She is not really into this sort or thing, but her grandma makes CS, and she swares to this day that CS was the only thing that helped! I think she may have used tea tree oil a little bit at first, but it didn't help much at all.
edit: You can get a
Colloidal Silver making report at
http://www.zapperplans.com and it tells you how to make it using 3 9 volt batteries instead of buying a generator.