Poison Ivy Poison Oak Poison Sumac. Poison ivy, oak, and sumac contain a substance called urushiol, which causes an itchy rash on people who touch it. Information about poison ivy, oak, sumac and the skin rashes they cause.
Another fact about poison ivy, poison oak and poison sumac is that coming in contact with them can be more risky in winter than in summer. Your first line of defense against poison ivy, oak, and sumac is being able to identify them outdoors. Most people are sensitive, they can cause a blistering skin rash.
Once you've identified poison oak, poison ivy or poison sumac, you can pull them up if you are very careful to wear protective clothing, eyewear, gloves and shoes.
To be allergic to poison ivy, you must come in contact with the plant once for sensitization to the oils to happen.
Poison ivy, poison oak, and poison sumac can causes an allergic reaction when someone comes in contact with the plant's oils. A rash from poison ivy, poison oak or poison sumac is caused by an oil found in these plants called urushiol. Information about poison ivy, oak, sumac and the skin rashes they cause.