DefinitionPoison ivy, oak, and sumac are plants that commonly cause an allergic skin reaction. The result is typically an itching, red rash with bumps or blisters.ConsiderationsPoison ivy is one of the most frequent causes of skin rash among children and adults who spend time outdoors. The plant can be found throughout the United States, except in the Southwest, Alaska, and Hawaii. It has three shiny green leaves and a red stem. Poison ivy typically grows in the form of a vine, often along riverbanks.Poison oak is primarily found on the West Coast. It grows in the form of a shrub and has three leaves similar to poison ivy.Poison sumac grows abundantly along the Mississippi River. It grows as a woody shrub. Each stem contains 7 - 13 leaves arranged in pairs.CausesThe rash is caused by skin