Poison Ivy, Oak, or Sumac - Topic Overview
What are poison ivy, oak, and sumac?
Poison ivy, oak, and sumac are plants that can cause a red, itchy rash called allergic contact dermatitis. It is the most common skin problem caused by contact with plants.
What causes a poison ivy, oak, or sumac rash?
The rash is caused by contact with a sticky oil called urushiol (say "yoo-ROO-shee-all") found in poison ivy, oak, or sumac. You can get the rash from:
- Touching or brushing against any part of these plants, including the leaves, stems, flowers, berries, and roots, even if the plant is dead.
- Touching anything that has come in contact with these plants, such as clothing, sporting gear, gardening tools, or pet fur.
The rash is only spread through the oil. You can't catch a rash from someone else by touching the blister fluid.
The rash is an allergic reaction to the oil. You become allergic to it through contact. After you have come in contact with these plants, your immune system may start to react to the oil as though it's a harmful substance.
What are the symptoms?
The usual symptoms of the rash are:
- Red streaks or general redness where the plant brushed against the skin.
- Small bumps or larger raised areas (hives).
Blisters that may leak fluid.
Some people are very allergic to the oil. In these people, even a little bit of the oil may cause serious symptoms that need medical attention right away, such as:
- Swelling of the face, mouth, neck, or genitals. The eyelids may swell shut.
- Widespread, large blisters that ooze a lot of fluid.
The rash usually takes more than a week to show up the first time you have a reaction to the oil. It develops in a day or two on later contacts. The rash may form in new areas over several days, but you will only get a rash where the oil touched your skin.
The rash usually lasts about 10 days to 3 weeks. But it may last up to 6 weeks in more severe cases.