Poison oak also can be eradicated by pulling out the whole plant. However, gardeners should wear protective clothes and gloves and make sure to get all the roots. Burning is not recommended because all parts of the plant are poisonous to humans. Dr. Aaron Schnier, a physician with the California Poison Control Center, San Diego Division, said the center gets calls from people who have been in contact with poison oak and from people concerned about indirect exposure from friends and family who have broken out in blisters. The substance that causes the allergic reaction is urushiol, an oil found throughout the plant.
People can have an allergic reaction to just a trace of urushiol.
Schnier recommends washing it from the skin and from items that may have had contact with the plants. What is interesting is that there is a delayed onset of the symptoms. It isn't something that you touch and get symptoms in a couple of hours. You can have delayed symptoms for up to a couple of weeks. Hikers should remember to wash the oil off any pets who may have had contact with the plant.