A low-growing, upright shrub that releases urushiol when damaged. This sticky oil is absorbed by the handler’s skin when the plant is touched. This oil causes an allergic reaction that includes blistering, swelling, and itching. Poison oak can grow to several feet tall. Poison oak leaves are duller in appearance than poison ivy and have hair on both sides. Its leaf shape looks like an oak leaf, but it isn’t part of the oak family.