Poison ivy and poison oak are toxic plants that commonly grow in the United States and Canada. They are members of the plant family called Rhus. These plants are similar in their appearance, growth, and effects on humans and can be more severe in spring and on new growth.
The poisonous ivy and oaks contain an oily substance, urushiol, which causes irritation and blistering of the skin. Human reactions vary from extreme susceptibility to near immunity. Just becoming older can have a tempering effect on the severity of the rash. The condition is most serious on children and young adults.
There are a group of new over-the-counter products created to be more effective at attacking the allergic reaction to urushiol, controlling the resulting itch and drying up the rash. The most popular of these are Tecnu, IvyStat and Ivarest. I've used Ivarest and it seems to be effective and works on other skin irritations. Read my Review: Ivarest Medicated Itch Cream