Poison ivy is an itchy skin rash caused by contact with oil from the poison ivy plant. In other parts of the country the same type of rash can be caused by contact with poison oak and poison sumac, plants which contain the same chemical but which don’t grow in New England. The skin rash usually develops 2 or 3 days after contact with the leaves or stems of the plant; sometimes the oil gets on your skin from handling clothes or pets that have come in contact with the plant. It usually consists of red areas with little blisters, often in a linear streaking pattern where the leaves have brushed against your skin.
If you come in contact with poison ivy, wash the oil off your skin with lots of soap and water within a half hour or so and you may avoid getting the skin rash.
Areas that get more heavily exposed to the oil break out before areas where the exposure is lighter, giving the appearance that the rash is spreading. However the fluid that seeps out from the blisters will not spread the skin rash to other parts of your body or to other people. You should be sure to wash the clothes and wipe down the shoes you were wearing so you don’t come into further contact with oil that might be on them.
Steroid medications are the mainstay of treatment for poison ivy. In milder cases a steroid cream like cortisone can be applied to the skin rash. For more extensive cases we prescribe an oral steroid like prednisone, or an injected steroid, depo-medrol.
To help with the itching, you can use an antihistamine like Benadryl or chlorpheniramine, but these usually cause significant drowsiness. You should avoid creams or sprays that contain Benadryl, because you may become allergic to Benadryl after applying it to your skin. It also helps to keep your skin cool. You can apply a cool compress or an icepack if you have a limited area of itchiness. If you are itching all over a cool bath or shower, or sitting in front of a fan or air conditioner, may help. Bathing with hot water will make your itching much worse, so it is best to use the coolest water you can without being uncomfortably cold.
If you develop oozing, wet areas, a compress with cold Domeboro solution may help. You can also use plain Calamine lotion to help dry these areas.