Urushiol

Urushiol is an oily organic allergen found in plants of the family Anacardiaceae, especially Toxicodendron spp. (e.g., poison oak, poison ivy, and poison sumac). It causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis.

Chemical Structure

Urushiol is a mixture of several closely related organic compounds. Each consists of a catechol substituted in the 3 position with a hydrocarbon chain that has 15 or 17 carbon atoms. The hydrocarbon group may be saturated or unsaturated. The unsaturated urushiol is more potent.

Exposure and Effects

Urushiol is absorbed quickly into the skin. It can also be inhaled if the poison plants are burned. The allergic reaction can take the form of extreme itching, with rashes, blisters, and severe inflammation. Approximately 80% to 90% of adults will develop a rash if they are exposed to .005 ounces of urushiol. Some people can become sensitized after a single exposure to urushiol.

Treatment

The primary treatment for urushiol-induced contact dermatitis is to wash the affected area with copious amounts of water and a mild soap (decontamination). Over-the-counter products are available that can remove urushiol from the skin, and reduce the severity of the rash if applied soon after exposure.

Prevention

Avoidance of the plants that contain urushiol is the best prevention. When it is necessary to work around such plants, protective clothing, including gloves, long sleeves, and pants tucked into boots, should be worn.

See Also

• Contact dermatitis
• Poison ivy
• Poison oak
• Poison sumac

Urushiol Resources
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