When I had a similar situation I ended up asking the Dr. for the shot as I was going to camp with the kids the next week. It helped some but I don't recommend wearing jeans on a multi-hour bus trip with inadequate AC if you have poison ivy! The camp nurse gave me a cream that helped but I don't know for sure what it was. I think it may have been prescription strength hydocortisone cream. Benadryl (pills or cream but not both) helps too if it doesn't make you so sleepy you can't function. Aloe vera gel helped too.