How to Identify, Treat, and Remove Poison Ivy

The definitive guide for how to identify poison ivy, treat poison ivy rashes, and remove this bothersome plant.

| July/August 2015

If you spend any amount of time in the outdoors, you probably know the saying, “Leaves of three, let ‘em be,” as well as you know those menacing leaves of three. Poison ivy, along with poison oak and poison sumac, might cause more misery than any other plant in North America; up to three out of every four people are sensitive to it. Poison ivy thrives in a wide range of places and is growing faster – and more potent – than ever before.

Once you’ve experienced a poison ivy rash, you won’t likely forget it. Inflamed red streaks form on the affected area, accompanied by a maddening desire – no, need – to scratch, made worse by the knowledge that scratching is the absolute worst thing you can do. Soon, small watery blisters form, popping and weeping. Contrary to common belief, these will not spread the poison ivy rash. Rashes on your face, between your fingers and toes, under your arms, or yes, in your groin, can also cause painful swelling. Hang in there; it’s going to be a rough week or two, possibly more. 

What’s the Rub?

All of this misery is thanks to a resinous oil, called urushiol, found throughout the plant – in its leaves, stems, berries and roots, pretty much everywhere. Poison ivy produces urushiol as waterproofing, not for defense; humans, lucky as we are, are the only species “blessed” with sensitivity to the stuff. Deer snack on the leaves, birds devour the berries (and incidentally, spread new plants, neatly fertilized, wherever they take a “comfort stop”), and dogs and cats roll happily in poison patches – and then bring the oil home to us. 

A little bit of urushiol goes a long way; enough to coat the head of a pin can have up to 500 people scratching in misery. It travels easily, transferring to Fido’s fur, your boots, your jacket, even the rake handle you used during last fall’s cleanup, then to you. Most times, you won’t even know you’ve been exposed to poison. That is, until the itching starts.

Urushiol is also incredibly stable, surviving up to five years, possibly longer, before it breaks down. This can make disposal tricky. Bag it up and send it to the landfill, or bury it deep – very deep. Don’t try to compost poison ivy green waste, and definitely do not burn it: Urushiol easily survives the temperatures generated in most brush and leaf fires. Worse, it permeates the smoke as a fine airborne mist. Breathing oil-laced smoke can be fatal, causing a reaction inside your lungs, sending you to the emergency room. Woodcutters beware. 

Oddly enough, urushiol itself is harmless; your own immune system creates all the misery. Once the oil soaks into your skin, your immune system identifies it as an invader, producing histamines to protect itself from attack. Instead, they betray your body, attacking the oil-soaked skin, creating the itching rash, blisters and swelling we all dread. The reaction can happen within one to four days after exposure, and can last up to three weeks.

6/19/2018 4:39:45 AM

Don't know if this really works since I do this as soon as I think I have 'possibly' been exposed: but DIRT... rub it over the touched spot-- why not? It's there; and dry material [ie kitty litter] is used to absorb oil... so why not? Can't believe that I've never heard it mentioned before... GREAT ARTICLE! … Pat.

6/18/2018 12:29:35 PM

First time I ever read about eating poison ivy to build up an immunity. My grandmother ate poison ivy every spring and I've never know her to have poison. I ,nor my brothers ever ate it. However it never bothered me, until recent years. Just surprised me!

6/18/2018 8:08:17 AM

I had an old, massive poison ivy infestation on the side of my house covering the first floor and starting up the second floor. I triple-rubber-gloved my hands and clipped the vines about a foot off the ground. That likked the vines above the cut. About a month later, when new growth from the ground was starting, I mixed up some Round-Up about 2.5 times the recommended rate and sprayed the new growth and a couple vines I had missed cutting. This has done wonders! I appreciate the tip about using garbage bags as gloves to pull down and bag the dead vines, as I'll need to do that. I think I'll probably still do the triple rubber gloves though. Thanks for the article! Chris, Dauphin County, PA

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