Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Many people are susceptible to the rashes of poison
ivy, oak,
and sumac.
The sap oil, called urushiol, causes the skin rash.
Poison ivy is not contagious.
Washing the oily sap from the skin with water and soap
immediately can help prevent the rash.
Avoiding direct contact with the plants can prevent the
rash.
What causes the rash? How do I identify poison ivy, oak, and sumac?
Poison ivy is a common cause of contact dermatitis, an allergic reaction to something that comes in direct contact with the skin. Allergic contact dermatitis as a response to plants is sometimes referred to as allergic phytodermatitis. This condition can be quite unpleasant but does not typically pose serious health risks. Prevention of the condition is best.
Poison ivy, oak and sumac are among the plants that produce a resin called an urushiol that can cause an allergic rash. These plants belong to the plant genus known as
Toxicodendron. The plants are found in different geographical distributions and are present throughout the U.S. except for desert areas, higher elevations (above 4,000 feet), Alaska, and Hawaii. (Poison ivy is most common in the eastern U.S. and poison oak and sumac in the Southeast.) The signs and symptoms produced by each of these plants cannot be distinguished from one another by their appearance. In addition, the same urushiols are also found in the mango, cashew, and
ginkgo trees. In the case of mangos, peeling the fruit prevents dermatitis. People who press the whole fruit, including the rind, against their skin can develop a severe reaction around the mouth. Those downwind from burning vegetation containing one of the offending plants can also develop widespread allergic reactions.
Identifying poison ivy, oak, or sumac
Both poison ivy and poison oak have three leaflets, while poison sumac more commonly displays leaflets of five, seven, or more that angle upward toward the top of the stem. Although it is often recommended that people learn to recognize the poison ivy plant ("Leaves of three, leave them be"), in practice, this can be difficult, since poison ivy and its relatives are often mixed in with other vegetation and not noticed until after the rash has begun. The leaves are shiny on their surface.
More than half the population can react to the poison ivy resin if they are exposed to it. Keeping the skin covered in situations in which exposure is hard to avoid is the best way to prevent the problem.
Picture of Poison Ivy Plant and Poison Ivy Skin Rash
Reviewed by William C. Shiel Jr., MD, FACP, FACR on 9/17/2012
Common Myths and Truths About Poison Ivy, Poison Oak, and Poison Sumac
Myth #7: Once the eruption occurs,
there are a variety of treatments that easily suppress the reaction and can be
performed without visiting your physician. They vary from applying human urine
to the site of the eruption to drenching the skin in gasoline. Truth: For mild
local reactions, it is generally necessary to apply potent topical steroids to
the site for two to three weeks. For more severe reactions, it is often necessary to take
oral cortisone (prednisone) in the appropriate dosage for two to three weeks.
Myth #8: There are barrier creams which can be applied to the skin prior
to potential exposures which can prevent the rash. Truth: In the April 2001
issue of the Skin Therapy Letter, two products are mentioned that appear to have
significant potential to act as a barrier to the chemical allergen: quaternium-18 bentonite cream (Ivy Block) and Stokogard cream.
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