|  | Conditions Treatments | Rashes

Description of Poison Oak Plant

There are two different species of poison oak: Pacific poison oak and its Atlantic counterpart. Both are shrub-like forms of poison ivy, so the best way to avoid getting a rash from either plant is to avoid them.

  1. Pacific Poison Oak

    • Pacific poison oak (toxicodendron diversilobum) is only found on the West Coast of the United States and Canada. It is one of California's most common woody plants and can be found from southern Canada to the Baja California peninsula. Its leaves resemble those of an oak tree, appearing in groups of three,with toothed or lobed edges. In direct sunlight, the plant grows into a dense shrub, and in shadier areas it grows into a vine.

    Atlantic Poison Oak

    • Atlantic poison oak (toxicodendron pubescens) is similar to Pacific poison oak, though its three leaflets are shiny and extremely hairy, and it produces hairy, white fruit that look like berries. It can be found in most Southern and some Northeastern U.S. states, including Maryland, Delaware and New Jersey, as well as Washington, D.C.

    Causes of Rash

    • The rash that some people get after contact with poison oak is contact dermatitis due to the oil, urushiol, in the leaves, stem, fruit and roots of the plant. When a person comes into contact with the plant, the oil rubs onto their skin, and that's when it can spread. Once it has absorbed into the skin it is no longer volatile.

    Urushiol Oil

    • Urushiol causes an allergic reaction in approximately 85 percent of the population that comes into contact with poison oak. At least 25 percent of those people have an extremely strong reaction to the oil, resulting in serious symptoms. For some, it takes just 2 micrograms of urushiol to cause an allergic reaction (see References 2). This oil is often transferred to other objects such as clothes, toys, animals, tools and can even be in the smoke from a burning plant.
      The substance causes no rash in about 15 percent of those who come into contact with it.

    Treatment and Duration of the Rash

    • The rash typically will run its course in two weeks or less. The best initial treatment is to wash the exposed skin with soap and water immediately after exposure to rid the skin of the oil so it is not transferred elsewhere.
      Further treatment depends on the severity of the outbreak. Contact your health care professional if you have a reaction located on your face or genitals, or if it has spread over a large part of your body. Prescription medications may include steroid cream, oral steroids or steroid injections.

Rashes - Related Articles