Poison ivy, which thrives in Riverwoods, can be seen as an individual plant or shrub growing close to the ground or as a vine climbing high into trees and onto walls and fences. Often reddish stems can be up to an inch in diameter, though when that large, they appear as woody, hairy brown vines. Poison ivy looks similar to several other plants. The plant has three leaves, with two of the leaves immediately opposite one another and the center leaf on a slightly longer stalk. In the Riverwoods area, the most distinguishing characteristic is that the two leaves opposite one another are each roughly in the shape of a mitten, with a large lobe and an adjacent smaller lobe. The size of the leaf, its glossiness, and the color of the leaf underside and stem, are not reliable identifying features.

As anyone who has had a major encounter with this plant can attest, it is a most unwelcome inhabitant of our area, producing an annoying and at times painful (and occasionally dangerous) blistering rash. The oily toxin, urushiol, causes this reaction and the severity (which sometimes requires medical attention) varies with individuals, and from year to year in the same individual. In most cases, sensitivity is developed only after one or more prior exposures to the toxin.

Because reaction to the toxin occurs when the toxin penetrates the skin, quick action – generally within about 5 minutes of exposure – will often avert a problem. Otherwise, redness and swelling typically appear within 12 to 48 hours after contact, followed by blisters.

If exposed to poison ivy, follow these steps:

  1. To avoid contaminating your home, remove contaminated clothing and, if possible, wash or rinse affected areas before entering the house.
  2. Cleanse your skin immediately with generous amounts of rubbing alcohol (isopropanol). If rubbing alcohol is not available, use soapy (or even plain) water. Be careful to clean only the contacted area, to avoid spreading the toxin to other parts of your body.
  3. Take a shower. Don’t reuse a soap bar used for the initial cleaning, as it may have been contaminated.
  4. Wearing disposable gloves and using rubbing alcohol, wipe off shoes, clothing, tools and anything else that contacted the toxin. Immediately and carefully discard the gloves after decontamination is complete.
  5. In severe cases of exposure, seek the prompt advice of a physician, as treatment must begin within a few hours after exposure to be most effective. A prescription corticosteroid may be appropriate. Because topical corticosteroid is not considered effective once blistering has begun, an oral version of the medication may be indicated.


Contrary to popular myth, no toxin is contained in the rash and blisters, so they are not contagious and will not spread. The rash and blisters appear only on the body parts that came in contact with the oily toxin, and typically disappear in two to three weeks. Mild cases may be relieved with wet compresses or soaking in cool water, and oral antihistamines can also reduce itching. Other helpful products include baking soda, calamine lotion, zinc oxide, and kaolin. For more serious cases, corticosteroid medication (hydrocortisones) may be advisable.

All parts of the plant, including leaves, stems and roots, are poisonous at all times of the year. Oil from the plant remaining on clothing and footwear can remain toxic for a year or longer. While dogs, cats and other pets are not sensitive to poison ivy, they can transmit the oily toxin on their hair. Other potential carriers are garden tools and anything else that comes into contact with the plant. Even smoke can contain the toxin and inhalation of toxin-bearing smoke can cause a medical emergency. For this reason, Poison Ivy plants should never be burned.

The best time to attempt to control poison ivy is from May through July, when the plants are flowering and most dangerous. Foliage can be sprayed with a general herbicide, such as glyphosate (sold under such brand names as Roundup), but again, remember this is a non-selective herbicide, and generally kills any vegetation it contacts. For that reason, take care to avoid desirable plants. Cut large vines a few inches above the ground, and immediately apply glyphosate to the freshly cut area. Since the chemical travels to all parts of the plant, doing so should kill the roots. Note that the vine and leaves will continue to contain the toxin, so they either should be left in place or removed and disposed of carefully. Since Poison Ivy is quite persistent, multiple applications of glyphosate may be required. Manual eradication is also possible, so long as all parts of the plant – leaves, vines and roots – are removed.