This poison oak rash is similar to the rash caused by poison ivy and poison sumac.
A classic case of poison oak might include a child with a known exposure to poison oak after a camping trip, hike in the woods, or day at the lake, who then develops a red, itchy rash all over his body a few days later.
Like poison ivy and poison sumac, poison oak is a member of the Rhus or Toxicodendron genus of plants. Unlike poison ivy, which is usually found growing as a vine or shrub east of the Rocky Mountains along trails, ponds, and lakes, poison oak usually grows as a bush or climbing vine in the western United States.
Urushiol is the chemical in all of these plants that causes the typical allergic reaction and symptoms of a poison oak rash.