Poison ivy can be the bane of many an outdoors person. If you are one of the about 80% of the population that is susceptible to it, it can be really annoying. And if you don’t seem to be one of the 80%, don’t get smug — the rash is an allergic reaction and you just may not have been exposed to it enough yet. There is still “hope” for you. (Sorry about that).
The substance in poison ivy that causes the rash is called urushiol. Supposedly it is a yellow liquid, but the trouble is that it is nearly impossible to see, so you generally don’t know if you have gotten any on you until the rash develops, and then it is too late.
There are a couple of things to keep in mind, though.
Probably the most important thing to know is how to recognize poison ivy. There is the old adage
Leaves of three, let it be.
That is actually not specific enough, for there are many other plants that have leaves of three. Two that come immediately to mind are the Box Elder tree (Acer negundo), a member of the Maple family, and various brambles like raspberries and blackberries. Since I have a couple of Box Elders on my property, I always have seedlings coming up (these trees are really prolific) that I have to look at twice to make sure that they are not poison ivy.
The main distinguishing additional feature of poison ivy is the smooth, shiny, waxy coat on the leaves. That pretty much gives it away.
Another thing to keep in mind, and this is what makes poison ivy so nefarious, is that the urushiol oil lasts a long time, as in years. If you get some on a tool or piece of clothing, you can get random rashes that you have no idea where they come from.
Finally, and this is the one related to going barefoot, you generally have to bruise the poison ivy plant to release the oil. That means that walking barefooted can give an advantage (not necessarily a large advantage, but an advantage nonetheless).
Bare feet don’t have the sharp edges and hard surfaces that shoes have, so they are less likely to bruise the plant in the first place. I should also mention that the soles of feet seem to be generally immune from it — the skin is just too thick to allow the oil to get to reaction depth (actually, I guess I should say that my sole is too think; I’ve never gotten the rash there).
You would think that hiking boots would provide protection. After all, they do cover all of your skin. The trouble is, when you take the boots off, you touch the invisible oil, get it on your fingers, touch another part of your body, and then the rash seems to inexplicably appear there. Nefarious indeed.
Right now I have a couple of small rashes in odd places. I have a short line of rash on the inside of one of my feet, at ankle level. I think that came from mowing the lawn, since I had a few poison plants that were trying to colonize it, and I suspect some oil got sprayed as I cut it. (Hint: wear latex gloves and pull out the poison ivy, being careful not to let it touch anything besides the inside of the plastic bag you put it into). But then I also have a patch just above my belly button (how the heck did that they there?). And on the back of my calf. It’s easy to say, well, you shouldn’t have been barefoot, but as I mentioned before, it could have been transferred from clothes or any other surface.
About the only thing you can do, if you think you’ve been exposed, is to carefully wash yourself off with warm, soapy water (the oil cleans off just like any other oil). A product like Tecnu also works quite well. Once you have the rash, hydrocortisone cream is supposed to help reduce the duration of the rash — to me it still seems like it takes forever. There are also products that will help tame the itch, like Calamine or even something like Lanacane.
An anecdote. Two years ago I was bushwhacking down in Zaleski State Forest along Raccoon Creek. I was exploring, looking for an easy ford across it, and found one that I knew would connect me with another trail on the other side. I found the ford, crossed it, and then started through the muddy flood plain towards the hills I knew the trail was at. And then I encountered a large field of poison ivy. At that point I had the choice of retreating or pushing forward through it.
I decided to push through and deal with the consequences later. I very gingerly eased my way through, being as careful as possible not to bruise them. And that seemed to work. I never got a single bit of rash.
Yet, other times, I have gotten rashes (on my legs) from lightly brushing overgrown poison ivy along horse trails. My suspicion is that horses had been by previously and had bruised the plants, releasing the oil, and that is what got onto me.
I think the bottom line with poison ivy is, you just never know. All you can do is know how to recognize it, treat it gently if you encounter it, and use warm, soapy water to try to remove the oil from wherever you think it might be.
Finally, we’ve lost, or are losing, a bunch of native plants. American chestnuts were wiped out by the chestnut blight. There was Dutch Elm Disease. Dogwoods are having trouble with anthracnose. There are Emerald Ash Borers. Et cetera, et cetera, et cetera.
Why oh why couldn’t we get a Poison Ivy Blight????

I don’t know. Sometimes it seems like I can get poison ivy by just looking at it wrong. I used to be one of those who never got it until one summer out surveying we got into it bad on a really hot day having to cut line of sight through it and some other overgrown thorny brush. Every scratch on me got infected with the stuff and I had to take medicine to help get over it. Since then I seem to get it pretty easily.
Dan,
I agree. The ways of Poison Ivy really are mysterious. Two years ago, when I went through that batch at Zaleski, I was fine the whole summer long. Yet, the past two summers, I seem to be getting it fairly regularly (never bad, though), and in weird places. Again, all I can figure is that there are patches of the oil sitting around in places I am unaware of (maybe my hiking stick) that I am coming into contact with.
What I do know is that my bare feet don’t seem to be getting it with any greater frequency than any other part of my body.