Everything You Wanted To Know About Poison Ivy (but were afraid to touch!)

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(updated 11/20/15)

“The poison oak or poison ivy (Rhus radicans), so abundant in the damp eastern forests, is feared as much by Indians as by whites. When obliged to approach it or work in its vicinity, the Cherokee strives to conciliate it by addressing it as ‘My friend’ (hí gĭnalĭi).”

~ James Mooney, Myths of the Cherokee and Sacred Formulas of the Cherokee


(excerpted from Secrets of the Forest by Mark Warren, © copyright 2015 by permission of the author)


During a plant class with twelve-year-olds, I was kneeling before a poison ivy specimen and explaining what the students needed to know about it, how to recognize it, what to do if they knew they had been exposed, and how to cure the rash with another plant’s juices. When I was finished, one student said proudly, “I can’t get it. I’m not allergic to it.”

As I was in the middle of explaining that such immunity can change at any time in a person’s life, the student – smiling broadly – plucked a leaflet and began rubbing her arms with it. We all watched with mixed reactions of doubt, horror, awe, and curiosity.

The next morning she came to me as the very portrait of misery. Her arms were covered in blisters. “I itched all night,” she whimpered. We walked together to harvest jewelweed and her problem began to resolve immediately. Her pride took a little longer.

Most of us are born into this world immune to poison ivy. But that can change at any time, even well into adult hood. When that happens, it almost always means that the allergy lasts for

the rest of a lifetime. However, there are contrary claims: Some people who as a child suffered a severe rash allegedly develop immunity as adults. And others, like those of African descent, may never become allergic. Contrary to rumor, Native Americans were allergic to poison ivy.

In the Southeast there are quite a few plants that can cause dermatitis to humans. Poison ivy, poison oak, and poison sumac are familiarly known by name, at least. Other rash-makers include black eyed Susan, dandelion, daisy fleabane, bloodroot, virgin’s bower, buttercup, pokeweed, Queen Anne’s lace, horseweed, mullein, yellow pine, pawpaw and Virginia creeper, to name but a few. But these plants are not universally problematic. I have handled all of the above, and, in my particular case, only the ones with “poison” in their names affect me. Sensitivity to plant irritants varies from person to person.


Poison oak looks so much like poison ivy that the layperson should consider them one and the same.
Contracting such a rash requires coming into physical contact with the plant (or through smoke, as we shall see later). The offending chemical, an oil named “urushiol,”   is manufactured in the leaves and then distributed to all other parts  of the plant: stem, roots, flowers, and fruit.

The rash usually spreads the same way, physically, by transferring oil from one locale on the body to another via scratching fingers, clothing, etc. If your dog has been sleeping in poison ivy just before you give her a hug, prepare for a mysterious outbreak along the inside of your arms. But there is more to the story than topical transference. In some cases the malady is known to have become systemic, pervading the body internally.

Some times we suspect poison ivy rash, when actually the problem is tiny critters that covertly insert mouth parts through the skin and induce itching … like chiggers, mosquitoes, ticks, and fleas. Since we often don’t see the animal, we might be inclined to accuse a plant.

Virginia creeper is a vine that is toxic – meaning: Don’t eat it! In the fall, when the leaves have turned to stunning scarlet and gold, this vine – also called “woodbine” – takes on irritant qualities to certain people who are sensitive to it.  It is this plant, more than any other, that I have heard people incorrectly assign the name “poison oak.” It is not. Poison oak looks so much like poison ivy that the layperson should consider them one and the same. And unlike poison ivy or poison oak, Virginia creeper has five (not three) leaflets, which are palmate (not pinnate). And Virginia creeper produces blue berries (not whitish/gray). Another plant often confused for poison ivy is a very young box elder maple.

Anatomy of a Rogue Plant

No one can render one drawing or take one photograph or point out one specimen of poison ivy as a reliable guide to ID-ing it.

Poison ivy is a compound plant, each of its three leaflets being ovate. Therefore, the old adage “leaves of three, let it be” should read: “leaflets of three …” (To avoid confusion, the term trifoliate is sometimes used for leaflets or leaves,of three.) But if you follow that folksy warning, you’re going to miss out on lots of other plants that typically show three leaflets, like tick trefoil, hog peanut, and young blackberry canes, all of which have edible parts.

Are compound plants that arrange their leaflets in three

pinnate or palmate? Three leaflets may not suggest a feather-

shape, as, say, the longer rows of leaflets on a locust or a

hickory tree. But if the three leaflets are all trying to point

more or less in the same general direction (toward the tip of

the compound leaf), then the leaf is pinnate – like poison ivy.

Virginia creeper’s five palmate leaflets spread in multiple directions from a common center, distributing themselves more equally among the 360 degrees of space available.

No one can render one drawing or take one photograph or point out one specimen of poison ivy as a reliable guide to identification. The plant has too many guises. Namely, this has to do with its teeth, which can be numerous, sparing or altogether missing. Thankfully, there are a few other nuances of the plant’s physiology that are most often useful in identification.

Where the leaflets’ edges neighbor one another, their margins tend to be smooth. The most pronounced serrations, therefore, usually occur on the two outside leaflets on their outside margins. If there are teeth present on the middle leaflet, they are usually close to the tip.

Each lateral-leaflet is asymmetrical, with more leaflet-blade material showing on the outside of its midrib vein than the inside. The middle leaflet is symmetrical.

The leaflet stalk (petiolule) of the center leaflet is longer than the other two. A burgundy-red pigment usually marks the point of their convergence. In autumn when the compound leaf drops away, the remaining scar is slightly raised from the stem like a tilted shelf. (Most leaf scars on other plants lie flat against the stem.) You can see these raised scars on older parts of the stem.

Poison ivy’s small, green, five-petal flowers emerge from the axil in late spring and early summer. If the flowers are pollinated they develop gray-white berries. Mature vines climb trees and boulders and develop a thick covering of air roots but no tendrils. These “hairy” vines, however, are not exclusive to poison ivy. Other vines look similar – climbing hydrangea being one of these. Climbing hydrangea’s leaves and branches and leaves grow opposite one another. Poison ivy grows its leaves (not leaflets) and branches in an alternate fashion, never opposite. Even in winter you can look at the bare branches of a vine and distinguish this by leaf scars.

When spring leaves first emerge they may be pale green, red, silver or any combination of these. As they mature the green color deepens and the surfaces of leaves take on a varnished sheen. If a leaflet is broken off, a milky sap exudes. Poison ivy can appear as an herb, a shrub, or a vine. When a vine – because of its far-reaching branches – it can be mistaken for tree branches from the supporting tree trunk. These branches can stretch eight feet or more from the stem of the vine.

What Makes Us Itch?

Once the oil binds to the protein in your skin, it will not wash off.

When poison ivy’s oil, urushiol, contacts us, our immune

system triggers a chain of events that can range from itching on

one end of the spectrum to death on the other. It takes about

fifteen minutes for the oil’s molecules to bind with protein in the epidermal cells. If the skin area is callused – say soles of feet and palms – it takes longer, or it might fail to bond. Urushiol is water soluble, but once the oil bonds with protein in skin, it cannot be washed off.

What does urushiol actually do? In small dosages, like touching a plant or two, it may do very little. It’s what the body’s immune system initiates next that wreaks havoc. It over-reacts. Why?  Because in large quantities urushiol carries the potential to suppress the body’s production of prostaglandin, a fatty acid, which, among other things, aids in the body’s battle against inflammation. The human immune system takes umbrage at an oil with this kind of potential. Even with minimal exposure to the oil, a fully-blown immune reaction can follow. The severity of the reaction varies from person to person. The immune “cavalry” of white blood cells and lymph crowds into the affected cells to do battle, causing blistering, tightening and itching.

The itching of urushiol-bonded skin can occur within two hours or less after contact. Or it could take a day or more. It depends upon a person’s particular sensitivity.

Viable urushiol can survive on the surface of objects indefinitely – depending upon its exposure to rain. Century-old dead and sheltered vines have been found to be storehouses of urushiol.

The rash that occurs from contacting poison ivy can develop into a systemic problem; that is, it can spread through the body internally. When that happens the situation becomes more serious, affecting T-cells in the immune system. I have not experienced this side of the poison ivy malady, but the pictures I have seen of victims covered with sores are sobering.

More commonly, the rash is spread inadvertently by topical transfer of urushiol to a new locale on the body. This might occur by contact with contaminated clothing or with house pets or simply by hand after scratching an itch. The liquid that oozes from the blisters of a rash is water-based and can dissolve any free urushiol at the site of the rash. Such “urushiol soup” can then spread and expand the afflicted area as well as be transferred to another site.


How do we protect ourselves?

Avoid contact with it. The easiest poison ivy preventative is being observant.

After contacting it, wash off immediately. Urushiol is water-soluble, so it’s an easy task to remove it. Soap is not necessary, though soap makes the job easier because it binds with oil, magnetically-speaking in the molecular sense. This makes the oil easier to rinse, and rinsing is the key step in this washing. If you simply cupped water in your hand from a creek and lifted that water to the exposed area and rubbed the water around, you’d be making “urushiol soup” and spreading it over a larger surface area. In a soap-less situation get that exposed body-part down in the creek and scrub. Let the current carry away the oil. If you wait too long to do this – say, an hour – all the washing in the world won’t rid you of the oil that has already bonded with the skin. But it will wash away unbonded oil, which might accidentally be transferred. If you use soap, spare the creek any soap pollution by washing at a sink.

Never tramp through poison ivy on a rainy day, even if you are wearing protective clothing. Every raindrop that sits on a leaf contains urushiol and can pass through porous clothing to contact the skin. If the clothing is not porous – like rain gear – urushiol remains on the outside but can drip down into your socks. If ever you use a tree for shelter during a rain, always examine the tree to look for climbing poison ivy vines. Make sure you are not standing in a poison ivy shower.

Apply a commercial urushiol shield to the skin. These can be found at sporting goods stores. I can’t speak for their efficacy, because I’ve never used them.

Never use an axe or chainsaw on a poison ivy vine, unless you are fully protected by clothing and safety glasses, or plan to wash soon. A severing blow with an axe can spray oil into the air.

Never burn poison ivy! Smoke carries the oil, which can then find its way to your skin by airborne means. Or worse, it can be inhaled to inflame the lungs – a condition that can prove irreversible and fatal.

*                       *                        *

What to do when you get the rash

When the rash appears, the first course of action is to wash/rinse the area thoroughly. Although oil that has already penetrated the skin cannot be washed away, any excess oil that has not yet bonded with the skin needs to be removed so as not to be transferred. Consider everything that might have had contact with the oil: clothing, fingernails, tools, tent, dog. Then wash those “carriers.”

Once you have washed the rash, it’s time to apply medication.

Many Native American poison ivy medicines were prepared as bark teas that were used topically to wash the rash – black birch, for example, whose inner and outer barks contain the analgesic methyl-salicylate (wintergreen oil). Tannic acid (tannin) is another chemical that can be applied. It’s a common astringent of Eastern forests and easily found in the root of New Jersey Tea (a shrub), in the bark of oak, beech and hemlock, in acorns, and in oak and chestnut leaves. The greenery of agrimony, cinquefoil, sanicle, and ragweed are other sources. Tannin draws up tissue, squeezing the immune fluid out of the blisters. It is also antiseptic, which provides a bonus by preventing infection of overly-scratched blisters.

Even considering all that is available from drug stores – calamine lotion, benedryl, hydrocortisone cream, diphenhydramine, astringents in alcohol, etc. – nothing works better than jewelweed, a wild impatiens, also called “touch me not” (for its “exploding” seedpods). This succulent plant grows in wet sunny areas, especially along large creeks or rivers where ample sunlight breaks through the parted canopy above the stream. By crushing any part of the plant,

Inhaling poison ivy fumes from a brush fire often leads to death.

a mucilaginous fluid is easily extracted, especially from the stem

(before the plant toughens in late summer). This juice contains

an anti-inflammatory agent, alleged to be kinder to the adrenals

and immune system than the cortisone synthesized in a lab. Smear the mucilage onto the rash, using the crushed plant itself as the applicator. Relief is immediate. Apply three times a day, each time using fresh material. Within a day and half the rash starts to subside and, throughout the treatment, itching abates.

An anecdote: The Cherokee classified “plant societies.” Poison ivy belonged to the “warrior society.” They named the plant “my friend” – perhaps to appease it – and believed that any medicinal plants growing in close proximity to poison ivy possessed extra potency.

Making yourself immune

Though there may be a risk involved for certain people, many outdoor enthusiasts create an annual immunity to poison ivy by eating one newly opened leaflet once a week for seven to nine weeks. I have been using this method for decades.

As proof, I picked a mature poison ivy leaflet and rubbed it briskly into the inside of my forearm.

Each April, when the leaves emerge from their buds, I ingest the first tender leaflet that I find. At this stage it is reddish and/or silver – the size of my little fingernail. I repeat this on a

weekly basis – one leaflet per week for nine weeks. As spring progresses, it becomes more difficult to find new leaflets, so I often  “farm” poison ivy by pruning to encourage new growth.

The first time I deliberately handled the plant, broke off a leaflet, and eyed the milky sap that beaded up on the broken leaflet stalk, I felt I was taking a leap of faith. But I knew of three people who used the immunity method successfully and without ill effects, so I took the plunge. I placed the leaflet on my tongue, chewed, swallowed, and began to imagine an invasive rash on my tongue, esophagus, stomach … and who knew where else! But all went well. Nine weeks and nine leaflets later, I ran a test. I picked a mature poison ivy leaflet and rubbed it into the inside of my forearm. I did not wash it off. After an hour a single bump – not a blister – rose up on my skin. It never itched. Fifteen minutes later, it disappeared.

A warning: I, of course, cannot guarantee the safety of this method for any one person. I am simply sharing my experience. I have learned of two persons who showed adverse effects after eating that first leaflet. Therefore, there is a gamble. Though it seems to be rare, the possibility for a backfire does loom. I have repeated this homeopathic immunization every spring throughout my adult life, as have dozens of my friends, and none of us has ever experienced a negative reaction.

This annual immunity lasts for me from late spring through midwinter. Only once did the method fail me. That was the year when I developed a rash in early spring before my nine-week installments were complete. Though I finished out the doses, I was not immune that year.

Does this plant have value?

Think of poison ivy as a teacher.

To ask such a question is a bit narrow-minded. It alludes to a presumption that all things in nature are designed for the benefit of humans. Ecology is an extremely complicated system of interactions. Though it may seem that we humans take center stage in the affairs of the

world, remember that the same might be said for dinosaurs in

their time. The earth fared very well through the eons before the arrival of mankind.

Plants continue to be one of our most crucial assets. As a green plant, poison ivy serves as one of those “friendly agents” capturing the sun’s energy for use on our planet. One of the by-products of this miracle that we call “photosynthesis” is the oxygen that we breathe and the recycling of the carbon dioxide that we exhale. I’ve seen deer, horses, donkeys and goats eat the leaves of poison ivy … raccoons, songbirds, and crows eat the berries. The flowers produce a nectar important to honeybees. If you could ask them about the worth of poison ivy you might get a more balanced answer.

Plants have evolved interesting methods by which to protect themselves from predation – by thorns or highly toxic chemicals – and we seem to have no trouble admiring those defenses, most of the time. We have even emulated these plant features by our inventions of barbed wire and pesticides, but we take poison ivy’s defense personally and feel persecuted to acquire its wrath when we take an innocent walk in the woods. Think of poison ivy as a teacher. Like venomous snakes, poison ivy sharpens our observation skills.


Mark Warren owns and directs Medicine Bow Wilderness School, teaching Native

American survival skills in north Georgia. For more information, call 706-864-5928 or

email Mr. Warren at medbow@alltel.net. To view the school’s class offerings, please

visit the Medicine Bow web site at www.medicinebow.net