How did I get poison ivy on me while I was working outside?

May 11, 2006

Question How did I get poison ivy on me while I was working outside?

Answer Everybody knows “Late at night when you’re sleepin’, poison ivy comes a creepin’ around.” Poison ivy (Toxicodendron radicans) is a woody, perennial vine or shrub found in fields, pastures, woodlands, and home landscapes. As a vine, it attaches itself to trees or other structures with hairy, aerial roots borne along the stem. Poison ivy has compound leaves that occur in threes. Remember the old saying, “Leaves of three, let it be.”

The entire plant is poisonous. It contains an irritating oil called urushiol. This oil is found in the resin ducts of the leaves, stems and roots. When the plant is injured, urushiol is released.

This oil is very potent and penetrates human skin in approximately 10 minutes from time of contact. After touching poison ivy, wash as soon as possible with soap and cool water. Warm water may cause the resin to penetrate the skin faster. Because urushiol can penetrate in a matter of minutes, you may still get a rash, but at least you have contained the infected area.

Urushiol can remain active for months on objects. It can be picked up on tools, clothing and pet fur. Therefore, anything that may be carrying the oil should be carefully washed. Even dead poison ivy plants may cause allergic reactions for a couple of years.

The plants are most dangerous in spring and summer when oil content is highest. This is also the time of year when weedeaters, lawn mowers and chain saws are slinging chunks of poison ivy plants in every direction. Long pants, long sleeve shirt, shoes and gloves make a good first line of defense when working around poison ivy.

For those sensitive to the oil, a linear rash, resembling small insect bites, will usually appear within 12 to 48 hours. Another interesting fact about poison ivy is that an individual's sensitivity can change over time. In other words, someone who did not seem to be allergic at one time may have a reaction at another time. Someone who is highly allergic may become immune to it. Usually this change in skin reaction happens over years and not days. A person's reaction may actually flip flop back and forth several times over the course of their life. Knowing this gives hope to the highly allergic gardeners. It also wipes the smug smile off the non-allergic person's face.

Poison ivy can rarely be controlled with one application of an herbicide. However, glyphosate (Roundup) or triclopyr (Ortho's Brush-B-Gon Poison Ivy Killer) will give you control over time. Early summer is the best time to apply an herbicide.

Refrain from burying your face in the fur on your dog's back. If you already have poison ivy on your face, now you may know how you got it. For more information about poison ivy visit http://ohioline.osu.edu/hyg-fact/1000/1015.html

If you don’t have internet access, don't hesitate to call the Extension Office at 893-7533, write us at PO Box 1089, Lillington, NC 27546, or email me at gary_pierce@ncsu.edu