Introduction to poison ivy, oak, and sumac:

It's Monday morning. You've had a wonderful weekend playing with your kids and your dog, romping through the woods. Now, as you lie in bed, you hear whimpering coming from the next room. A few minutes later, your son comes in to join you in bed, sporting red itchy patches on his arms and legs. He has poison oak (or poison ivy, or poison sumac).

What is poison ivy, oak, and sumac?

Poison ivy, poison oak, and poison sumac together produce more cases of allergic contact dermatitis than all other allergens combined. The resulting rash can be anything from mildly unpleasant to a true emergency with intense swelling, blistering, and oozing. With even a moderate case, as you may have experienced, the itching can seem unbearable.

Whichever of these plants he came across while playing, the culprit is the same -- an oil called urushiol. This oil is found in the leaves, roots, and twigs of these plants. There is no difference in the rashes, since there is no difference in the cause. A few other plants contain the same oil in lesser amounts, including the Japanese lacquer tree (and thus some lacquered furniture), the gingko tree, the shells of cashews, the shells of brazil nuts, and the rinds of mangoes. Extra sensitive individuals would do well to avoid all of these.

Who gets poison ivy, oak, and sumac?

Most people will have no reaction the first time they are exposed. In fact, children under the age of 7 are rarely sensitive. Sensitivity is particularly rare under the age of one, and when infants do break out, the rash is usually mild. As many as 15 –30 percent of individuals never develop sensitivity.

The rash is most common in the summer, but it can occur at any time of the year.

What are the symptoms of poison ivy, oak, and sumac?

Wherever the oil touches the skin of a sensitive individual, an exquisitely itchy, red rash will appear between 8 and 72 hours (usually 12-48 hours) later, which will often go on to develop blisters. The first time a person touches this oil, s/he may break out 7 to 10 days later.

Is poison ivy, oak, and sumac contagious?

The oil from poison plants can stick to virtually anything. It can dry and remain potent indefinitely. This is why camping trips can produce such horrible cases of poison oak. Anything that your child has touched between his exposure and a thorough shower should be washed in soap and water (preferably hot), hosed down, or soaked in water and alcohol. This includes clothing, shoes, balls, toys, tools, and the towel he used after his shower. After washing the contaminated articles, don't forget to wash your own hands, and anything those articles touched.

Once the oil has been removed, the rash from poison oak or poison ivy is not contagious. Even the oozing blisters are not contagious, although they look like they should be. Because new blisters can keep appearing over the course of a week, people assume that touching the rash causes it to spread, or that the ooze itself is responsible for the spreading. The fluid that fills the blisters is one's own serum, not the poisonous oil. The skin only breaks out where it actually is exposed to the urushiol. The sensitivity of the skin, and the amount of oil, determine the speed of the eruption.