Risk Factors and Causes of Poison Ivy, Poison Oak, and Poison Sumac

Exposure to poison ivy, poison oak, and poison sumac can cause an allergic reaction. The characteristic itchy rash develops in response to contact with a substance called urushiol. This substance is present in the leaves, stems, and roots of the plants.

Reactions can occur following direct contact with the plant, through indirect contact (e.g., touching an object that has picked up urushiol from the plant, such as gardening tools and pet fur), and through airborne contact (i.e., burning the plants can release urushiol particles into the air).

People who spend time outdoors in areas where poisonous plants grow are at increased risk for developing an allergic reaction. Wearing long pants, long-sleeved shirts, and gloves while working outside can help reduce the risk. Washing exposed areas of skin with soap and water within 30 minutes of possible exposure also can reduce the risk. Clothes, tools, sporting equipment and other objects that may have come in contact with the plants should be handled with care and washed thoroughly.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 24 Aug 2007

Last Modified: 03 Aug 2010