Overview
Poison ivy, oak, and sumac plants contain an oil called urushiol. Leaves, stems, roots, and berries of all of these plants cause the same type of skin rash. Upon contact with the skin, the oil can trigger an allergic reaction that can appear within hours of the exposure up to several days later. It is important to note that an affected person may experience an allergic reaction by coming into contact with the oil either directly (ie, by touching the plant) or indirectly (eg, by touching gardening tools, pet's fur).
The itching is usually intense and the affected person can develop itchy bumps (papules) or blisters (vesicles). While a poison ivy, oak, or sumac rash is not initially infected, secondary bacterial infection can result from scratching the bumps or blisters. The lesions are not spread by scratching, however; the lesions with the most antigen appear first and then, as the immune response increases, lesions with less antigen begin to erupt.
