Herbal or Eastern treatments... Dunno.
Western... working with an incredibly intelligent ER Physician right now... worst case P.I. treatments often do well with tapered doses of oral Prednisone, Calamine lotion, and/or for unblistered sites, Cortisone based creams.
Now that you've got it once, (become sensitive, or more sensitive to it) you will continue to get it.
Poison Ivy reaction occurs within about the first hour of contact with the leaf. You have about that time to best wash it off with warm soapy water... or cold. If you touch an area of contact (ie. clothes) and touch somewhere else, (ie, sweaty forehead, weiner, whatever) you are likely to get it there. If you develop blisters, the fluid within (weeping out) can spread to more sites from that contact. At the blistered stage there is a low incidence of communicability, higher incidence of you spreading to more areas on yourself.
If clothes worn, or pet remains unwashed, it could cause later reactions in another area. Smaller incidence of reoccurrence or new sites if say, leaf to clothes to car seat to skin were to happen, but that's slim Also, with a very small percentage of people poison ivy can "possibly" spread internally, and with those people only an internally administered medication will help.