In a previous answer, I described some surprising facts about where this rash comes from and how it might spread . In this answer I will focus on what to do once you have been unfortunate enough to contract poison ivy, poison oak, or poison sumac. Most of the treatments are aimed at reducing the itching, until the self-limited rash runs its course, which takes about two weeks. Since easing the itching is the important result, trial and error works very well. If one of these suggestions seems to work, by all means, stick with it.
Most people find that cool compresses in one form or another are quite soothing.
This can help relieve the intense itching and remove dry crust that has formed as a result of the rash. A fan blowing over the cool compress will diminish some of the heat of the itching and help to dry up some of the ooze coming from the rash. As the skin is cooling, the blood vessels compress and that cuts down on the itching and the new ooze. This is especially good during the two or three worst days of the rash. Along the same lines, some dermatologists recommend rubbing an ice cube gently over the rash several times a day, then letting the skin air dry.