Causes of Poison Ivy, Oak, and Sumac Rash

The rash caused by poison ivy, oak, and sumac is an allergic skin reaction to an oil, called urushiol, which is in the plant. This oil is found in all parts of the plant, including the leaves, stems, roots, and berries.

• Exposure to the oil occurs through any of the following:

• Touching any part of the plants

• Touching clothing or other objects that have contacted the plants

• Touching pets or other animals that have contacted the plants

• Exposure to the smoke of burning plants

• For more information about how these reactions occur, see Allergic Reactions and Contact Dermatitis.