 The fluid in the blisters is produced by the body and it is not urushiol itself.The appearance of a spreading rash indicates that some areas received more of the poison and reacted sooner than other areas or that contamination is still occurring from contact with objects to which the original poison was spread.Those affected can unknowingly spread the urushiol inside the house, on phones, door knobs, couches, counters, desks, and so on, thus in fact repeatedly coming into contact with poison ivy and extending the length of time of the rash.