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Poison Ivy, Oak, and Sumac

Poison Ivy, Oak, and Sumac Overview

More than half the people in the United States are sensitive to poison ivy, poison oak, and poison sumac. If an individual is sensitive, he or she can develop an itchy, blistering rash by coming into contact with these plants.

  • Whether working or just enjoying the outdoors, look out for these plants, and note the differences between each:
    • Poison ivy is generally found east of the Rocky Mountains, growing as vines or shrubs. The leaves can have either smooth or notched edges and are often clustered in groups of three.
    • Poison oak is more commonly found west of the Rockies, usually as a small bush but sometimes as a climbing vine. Its leaves are smooth-edged and cluster in groups of three, five, or seven.
    • Poison sumac is most often found in wet areas of the Southeast. The leaves are generally smooth and oval-shaped, with seven to 13 growing on each stem.
    • The appearance of each of these plants can vary considerably from region to region and with the seasons. Even dead plants in underbrush can transmit the toxic oil to the skin. Identification of these plants can help one avoid them.

Causes of Poison Ivy, Oak, and Sumac Rash

The rash caused by poison ivy, oak, and sumac is an allergic skin reaction to an oil called urushiol that is inside the plant. This oil is found in all parts of the plant, including the leaves, stems, roots, and berries.

Exposure to the oil occurs through any of the following:

  • Touching any part of the plants
  • Touching clothing or other objects that have contacted the plants
  • Touching pets or other animals that have contacted the plants
  • Exposure to the smoke of burning plants

Poison ivy, oak, and sumac rash itself is not contagious. However, if oil remains on the skin or on clothing that came in contact with the plants, and the oil comes into further contact with skin, a rash may result. The rash may appear to "spread" because it can develop over several days, or it's possible the oil was not entirely removed from all surfaces.

Risk factors for developing poison ivy, oak, or sumac rash include being in areas where the plants grow, engaging in outdoor activities, and coming into contact with them.

Medically Reviewed by a Doctor on 6/12/2015

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