Poison Ivy (Toxicodendron Radicans)
Poison ivy, poison oak, and poison sumac are closely related species, all three containing a colorless or slightly yellow oil called “urushiol.” Skin contact with this oil causes an allergic reaction. While each of these three plants contains a slightly different type of urushiol, they are so similar that children sensitive to one type will react to all three. The entire plant contains urushiol and is therefore poisonous: leaves, berries, stalk, and roots.
Urushiol is easily transferred from the plant to an object and then to a child, so anything that touches these poison plants—clothing, gardening tools, a pet’s fur, athletic equipment, sleeping bags—can be contaminated and cause poison ivy in anyone who touches the object. Urushiol remains active for up to one year, so any equipment that touches poison ivy must be washed. The smoke from burning poison ivy is especially toxic to the skin of the face, the eyes, or the lungs. It will also irritate the throat if eaten.
As the leaves die in the fall, the plant draws certain nutrients and substances (including the oil) into the stem. But the oil remains active, so that even in winter it may cause a rash if the broken stems are used as firewood, or the vines on a Christmas wreath.
Despite persistent folklore, poison ivy is NOT spread by scratching open blisters or by skin-to-skin contact. Only the oil can trigger a reaction. However, doctors recommend that a child not touch the blisters, because any remaining oil on the skin that has not been washed off could be transmitted to another part of the body. Scratching blisters also may cause infection from germs on the skin surface.
While not every child is allergic to poison ivy, about seven out of 10 are. Symptoms vary from one person to the next; some children exhibit only mild itching, while others experience severe reactions. Within 24 to 48 hours after exposure the skin becomes red, followed by watery blisters, peaking about five days after contamination and gradually improving over a week or two, even without treatment. Eventually the blisters break, and the oozing sores crust over and then disappear.
The best treatment is to immediately remove jewelry and wash the affected area (within 10 minutes if possible after contact) with yellow laundry soap and cold water. A shower is better than bathing in a tub, since the latter could spread the oil. If a child is contaminated in a remote area, washing in a cold running stream will help remove the oil. Any clothing that may have come in contact with the oil must be washed several times.
Early application of topical steroids can minimize the severity of the skin reaction. Itching can be treated by applying cold compresses; a calamine lotion spread over the rash will help ease itching and burning. Products containing local anesthetics (such as benzocaine) or irritants (such as camphor or phenol) should be avoided.
Systemic antihistamines do not work against the rash, although their sedative action may help the child sleep. In the case of a severe reaction, a doctor may prescribe corticosteroid drugs by mouth or injection. Such systemic steroids given during the first six hours after exposure are the most effective.
New barrier creams (bentoquatam) may offer some protection and should be applied 15 minutes before exposure is suspected, and every four hours afterward. It should not be used if a rash is already present, nor on children under age six.
Most people could be immunized against poison ivy through prescription pills, which contain gradually increasing amounts of active extract from the plants. However, this procedure can take four months to achieve a reasonable degree of hyposensitivation, and the medication must be continued over a long period of time. In addition, it often causes uncomfortable side effects such as skin problems, stomach problems, fever, and inflammation. Convulsions have occurred in children after oral doses of the plant’s extract.