This condition is an inflammatory reaction caused by contact with urushiol, an irritant found in the sap of some species of plants (most notably poison ivy, poison oak, and poison sumac). Even a tiny amount of this oil is enough to cause a reaction in most people.
Poison ivy is found throughout the eastern United States and Canada and in the mountainous regions of Mexico. It grows as a vine or a shrub, and is identified by clusters of three green leaflets that turn red in the fall.
Poison oak grows in two varieties. Atlantic poison oak is a shrub found in the southeastern United States. Pacific poison oak grows as a shrub or vine on the Pacific coast from Baja California to Canada. Both varieties have clusters of three leaves.
Poison sumac grows in wetlands and bogs throughout the eastern United States and Canada. It grows to form small trees, and has feather-shaped leaves with red stems that cluster in odd groupings ranging from five to thirteen. It has small white flowers and small hanging berries.
The best way to prevent this type of contact dermatitis is to avoid the sap of these poisonous plants. This can sometimes be difficult, because the sap can be transported on shoes, clothing and pet fur. It may also become airborne when a poisonous plant is chopped up with a string trimmer or a lawnmower. If you do come in contact with one of these plants, wash the skin as soon as possible with soap and cold water for several minutes. Handle contaminated clothing carefully, and wash it as soon as possible in detergent.
When the sap of one of these poisonous plants comes in contact with the skin, the urushiol contained in the sap immediately begins to penetrate the epidermis. Within minutes it reaches the dermis, where an allergic reaction takes place in people who are sensitive to this chemical.
Symptoms begin soon after exposure, usually within 12 to 48 hours. The skin may become red, warm and swollen. The affected area may become very itchy. As the reaction progresses, blisters may form. They may break and ooze and form a crust. The reaction can last for up to three weeks.
Treatment options may include over-the counter creams and ointments. In severe cases, a prescription corticosteroid cream or oral medication may be recommended.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.