how long does it take poison ivy to show up
A window of 12-72 hours is the range within which the allergic reaction to poison ivy [Toxicodendron diversilobum and Toxicodendron pubescens] tends to show up. Chances are that the reaction will show up closer to the lower than to the upper range. But a way of preventing or lessening the reaction is the washing of the affected area several times, and thoroughly, with soap and water. 2 people found this useful.