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Poison Ivy, Poison Oak, and Poison Sumac

Poison ivy, poison oak, and poison sumac are plants that are well known for causing an itchy rash when the plants come in contact with a sensitive individual.  All parts of these plants contain the same oily pale-yellow liquid resin called urushiol.  It is the contact with the urushiol that is responsible for causing the rash.  The itchy rash can occur from touching any part of the plant including the leaves, flowers, berries, roots, and/or stems whether the plant is dead or alive.  Likewise, coming in contact with anything that has touched the plants, such as clothing, shoes, fur from animals, garden tools, or lawn mowers, can also spread the urushiol.  It is actually an allergic reaction to the urushiol liquid of these plants that is the real cause of the rash.  These plants are a very common cause of contact dermatitis.  Poison ivy is the most common of these plants.  The scientific names for poison ivy, poison oak, and poison sumac are Toxicodendron radicans, Toxicodendron diversilobum, and Toxicodendron vernix respectively.  Of note, poison oak is mainly found in the western part of the U.S., and is sometimes called Western poison oak, however, there is a species of poison oak, sometimes referred to as Atlantic poison oak that is found in the southeastern U.S., including Virginia.  This Atlantic poison oak has the scientific name of Toxicodendron pubescens.

The rash that is caused by poison ivy, poison oak, and poison sumac can vary in severity.  An individual must be sensitive to the urushiol found on the plants to have a reaction.  The symptoms of the reaction include itching, small to large red bumps, red streaks (which typically follows a linear pattern where the plant brushed up against the skin), and/or blisters (that contain fluid which may leak).  Sometimes, usually due to scratching, the rash can become secondarily infected.  The typical symptoms usually begin between 24-48 hours after contact with the plants.  Sometimes, it can take a longer period of time to develop symptoms, particularly if it is the first time that a person has a reaction.  The rash usually lasts 2-3 weeks in duration, but can persist much longer in some people.  The rash can begin in one or two locations of the skin and then develop in another area of the skin which gives the appearance that it is spreading.  In fact, it does not actually spread, as contact with the urushiol liquid is necessary in order to develop the rash.  It is however possible to spread the oily liquid from one area of the skin to another area with one’s fingers, thus causing another rash to develop in that new area.  One common misconception is that the blister fluid can spread the rash to a new area of the skin.  To be quite clear, the leaking fluid from a blister does not spread the rash.  Some individuals can get diffuse large blisters which can be confused with other skin diseases that cause blistering.  It is therefore important to see a board certified allergist so that the correct diagnosis can be made and the appropriate treatment administered.

It should be noted that on occasion, the symptoms in some individuals can be very severe leading to swelling (angioedema) of the face, lips, throat, eyes, and/or neck.  It can even cause difficulty in breathing and/or swallowing in severe cases, which can lead to unconsciousness.  Persons who exhibit such severe reactions should go immediately to the closest emergency room at the nearest hospital for treatment.

There is a very important fact that people should know about poison ivy, poison oak, and poison sumac.  That is, inhalation of the smoke from burning poison ivy, poison oak, and/or poison sumac can be very serious.  The soot of the burning plants contains urushiol, which when inhaled can cause the lungs to swell.  Symptoms can include coughing, swelling of the throat (angioedema), shortness of breath, and/or blisters in the airways.  If someone is exposed to the smoke from any one of these burning plants, they should seek medical care immediately at the emergency room of the closest hospital.

In order to prevent further outbreaks of poison ivy, poison oak, and poison sumac in a sensitive individual, first learn to identify what the plants look like, so that one can avoid them while outdoors.  When hiking, gardening, etc., it would be advantageous to wear long sleeves, long pants, leather or vinyl gloves, and closed shoes in order to decrease the likelihood of coming in direct contact with the plants.  When returning home, wash clothes immediately to remove any urushiol that may have gotten on the clothing.

The treatment of poison ivy, poison oak, and poison sumac begins with the individual washing the affected skin with a mild soap and cool water to try to remove the oily urushiol if you think you came in contact with any of these plants.  Do not use hot water as this will open up the pores of the skin which will allow more absorption of the urushiol.  Calamine lotion can be applied for minor skin reactions which acts as a topical anti-itch lotion.  Zinc oxide ointment can also be used on the affected skin as it reduces the inflammation found in minor reactions.  Prescription strength oral antihistamines and corticosteroids are frequently necessary for more pronounced reactions.  Occasionally, antibiotics are necessary to treat secondary infections that can occur.  If the reaction does not improve and/or gets worse when only using over the counter medications, it is important to see an allergist.  The board certified allergists at Black & Kletz Allergy will see you as soon as possible so that we can intervene quickly in order to relieve your symptoms and make you feel comfortable.  Call us at one of our 3 office locations in Washington, DC, McLean, VA (Tysons Corner, VA), or Manassas, VA to make your appointment.  Alternatively, please click Request an Appointment and we will respond within 24 hours of the next business day.