Poison Ivy (Toxicodendron radicans)
They’re here! Poison ivy that is, and her two toxic siblings poison oak and poison sumac. The bane of summer enjoyment for gardeners, landscapers, campers, hikers, and lovers of all things outdoors.
Each year, 50 million Americans endure the ramifications of a toxic encounter with poison ivy and her two pernicious allies. However, it was only recently that researchers identified the molecular pathway that had eluded them in the past. More about that in a bit.
Yet, for those who lead plant identification groups, “Is that poison ivy?” has to be one of the most commonly asked questions and for good reason. Poison ivy does not always present exactly the same, but once one masters its ambiguous nature, it seems to pop out of everywhere. So let us learn a bit more.
Know Your Enemy
Poison ivy, poison oak, poison sumac, and the Japanese lacquer tree are part of the cashew plant family. Originating as a North American native plant, poison ivy is found from coast to coast in Canada, the continental United States (except for California where poison oak abounds), and Mexico. It has a great ability to adapt to many different habitats which is why it can be found growing almost anywhere except in the desert or at high elevations.
In the eastern part of the United States one will typically see poison ivy as a climbing vine that looks like a hairy rope with flowers of green or yellow. While western poison ivy, although similar in appearance, typically does not climb, but instead grows into a low-lying shrub. To confuse the issue, western poison oak has a vining growth habit.
The edges of the leaves are called margins. They can either be smooth or toothed. Sometimes on different plants, and sometimes even on the same plant as in the one depicted below. Also, poison ivy can also present with many “teeth” on the toothed margins, not only the one notch depicted here.
The young plants or leaves usually have a “high-gloss” appearance and can range from green to greenish-red to deep red color. In the autumn, poison ivy leaves turn a deep orange to red color. It is simply beautiful to behold.
~ Leaflets of Three, Let It Be ~
While the edges of the leaves can be either toothed or smooth, the leaves themselves are pinnately-veined, making them a dicot. Dicots are a grouping of flowering plants that typically have four or five petals. Poison ivy flowers have five petals which flower in June.
~ Longer Middle Stem, Don’t Touch Them ~
The leaf presents at the end of a petiole in a grouping of three leaflets called “trifoliate” or “ternate.” A petiole is the “leafstalk,” which is a slender stalk that attaches the leaf or leaves to the stem of a plant. Also note in the photo above that the center leaflet has a longer stalk than the two opposite leaflets.
The fruit of poison ivy is called a drupe which is a fleshy fruit that surrounds a single stone-like seed and is colored greenish-yellow or amber. These fruits are a valuable source of food for birds during mid-winter when food is scarce.
Two simple mnemonics are just not enough to describe this “plant of many presentations.” Therefore, when describing the eastern poison ivy it is important to take note of that hairy vine. What child would not delight in repeating the phrase “Hairy rope? Don’t be a dope!” So let us stick with more refined terminology, “Hairy vine? No friend of mine!”
~ Hairy Vine? No Friend of Mine! ~
The next photo shows three poison ivy vines, two of which are quite thick. Touching any part of poison ivy plant can result in a form of contact dermatitis called “poison ivy rash”, which is a type of skin poisoning.
The photo below is a close up of those “vine” hairs for your consideration, but did you know that poison ivy is neither a vine nor a plant called a bine? A vine has tendrils which are used to climb, think of a grapevine, sweet pea, cucumber, or passionflower.
A bine uses its main stem to wrap around the thing that it is climbing like a fence post or a tree. Examples of plants that are bines would be hops, wisteria, honeysuckle, morning glories, or clematis.
Poison ivy is neither a vine or a bine. It is actually a parasitic plant. Those “hairs” used to attach itself to trees are, in fact, aerial roots which gain nourishment from its host.
~ To learn more about botany and the medicinal properties of plants consider the Master Herbalist program at Genesis School of Natural Health! ~
Toxicondendron radicans while native to North America can also be found alive and well in Europe and Asia, and disbursed from there all over the world. In the fall of 1784, “Philadelphia horticulturalist William Bartram wrote out a list of 220 “American Trees, Shrubs, & herbs” in his fine, flowing handwriting. He was packing up seeds and young plants to send across the Atlantic, as he had many times before. European collectors were eager to buy New World trees and plants, whether useful, ornamental, or simply unusual.” Number 120 on his list was poison ivy.
From there poison ivy began to be cultivated in English and French royal gardens. It was not long before the plant’s irritant effects became well known and its popularity dwindled. I wonder is it just me, or can anyone else picture a wry smile on ol’ Bartram’s face as he was writing out his list?
Poison ivy is a rich source of tannins, saponins, alkaloids, etc. It is also high in antioxidants and in antimicrobial activity. The oily mixture of sap contains Urushiol, a clear chemical that causes skin irritation and itch. Urushiol found in the Japanese urushi or “lacquer” tree is also found in poison ivy, poison oak, poison sumac, and the skin and plant parts of mangoes.
It is the alkyl functional groups that make urushiol non-polar and hydrophobic. This means it does not dissolve in water. When oily urushiol touches the skin, it sticks and begins to be absorbed right away into the dermis over the next eight hours or so, unless measures are taken to stop it.
If not removed from the surface of the skin an itchy rash generally begins to appear in as few as 24 hours from the initial exposure. The molecular pathway for this irritating effect of urushiol had previously eluded scientists, until now.
Florian Winau, Assistant Professor of Microbiology and Immunobiology at Harvard Medical School found that “when urushiol comes into contact with Langerhans cells in the skin, the Langerhans cells load urushiol on CD1a molecules that activate the immune system’s T cells. The T cells produce interleukin 17 and interleukin 22, which cause inflammation and itchiness. It was these two interleukins, known to be active in psoriasis as well, that prompted Winau to suggest that a similar mechanism — and a similar therapeutic target — may be involved in both the poison ivy response and in psoriasis’ auto-immune reaction.”
Why had this evaded researchers for so long? Well, lab mice are often used in immunology study and while they are valuable resource in many respects, no one considered that they don’t produce CD1a, the molecular pathway found in humans allergic to urushiol.
~ “Phytochemistry”, understanding how and why plant medicine works, is foundational in the Clinical Master Herbalist program here at Genesis School of Natural Health! ~
~ Ewww! Get it off-fa me! ~
While we need to be able to avoid direct exposure to the poison ivy plant, we also need to be cautious about possible secondary exposures as well. Toxic urushiol can remain active for up to five years on clothing, bedding, shoes, tools, gloves, and pet fur if not cleaned off. Dead, dried-up poison ivy still has the oil on it. So beware.
“Urushiol must penetrate the skin to cause a reaction, and can depend on the amount of sap, the length of exposure, and the parts of the body exposed (skin can be thicker or thinner depending on the part of the body). It will also depend on your individual sensitivity.”
To remove the urushiol, use lukewarm to cool water and scrub with a cloth. It is the friction that actually removes the oil, so don’t be afraid to give a good scrub. Do not use hot water as it opens the pores of the skin and increases the rate of absorption. Believe it or not cool water and friction are more effective at removing poison ivy oils, than even soaps and chemical products. The best practice is to soap up, scrub, and rinse two to three times making sure to get any place on your body that you may have touched with your hands.
Do not bathe in an attempt to remove urushiol. The still unabsorbed urushiol can float on the bath water and find its way to other parts of the body. There are products like Tech-nu and de-greasing soaps that are marketed, but by far the most effective way to remove urushiol is by pure friction.
Remember to clean well under the nails because urushiol can stay active for quite a while in that hiding spot.
~ Stop the Itch! ~
So ya got yerself some poison ivy goin’ on. Well, of course, it was before you read this article and knew all about it, but that does not change the fact that now there is an inflamed rash that itches like a bugger. What can help while the body is healing? First, do not scratch or break open the blisters. The blisters are self-protective fluids that help to cushion the wound, keep out infection, and heal the skin.
Here are a number of things to try, so don’t give up.
~ Cool as a Cucumber! ~
- My personal favorite soothing, anti-heat, anti-itch remedy is to place lengths of thinly-sliced cucumber directly upon the rash and wrap it in a layer of paper toweling secured by cellophane wrap. I may look like a country bumkin in that getup, but there is nothing more soothing than cucumbers which are especially cooling. Such a relief from the heat of the inflammation and the incessant itch. Cucumbers are also astringent which helps contract the tissues and diminish the secretions.
- Another way to use cucumber is to liberally rub the juice over the rash. Let it air dry after the application, then apply a second coat. This provides a protective layer over the rash that keeps it from being irritated by fabrics and things one brushes up against throughout the day. Two coats each time seems to do the trick, is easy to reapply, and lasts a few hours. Others swear by watermelon rind or the inside of a banana peel, but I don’t know if they have tried cucumber. Try whatever is available to see what helps your situation the most.
- Aloe (Aloe vera) – Now might be a good time to slice open a leaf of that plant you keep around for burns and sunburn and smear it all over that rash. Aloe gel can help too.
- Activated Charcoal can be helpful, especially where there is severe swelling. Take 8 tablets or mix 1 rounded teaspoon into a small glass of juice or water two times each day. Remember to increase water intake while using activated charcoal. Discontinue once the swelling has dissipated.
- Apple Cider Vinegar – Saturate a cotton ball and apply topically with a saturated cotton ball.
- Oatmeal Paste – Use plain or stir in some baking soda.
- Calamine lotion is commonly applied to urushiol rashes.
~ Poison Ivy Herbals ~
According to Dr. John R. Christopher, naturopathic physician and herbalist, poison ivy is listed along with herbs that are known irritants. Irritants are “Herbs that produce a greater or lesser degree of vascular excitement when applied to the epidermis or skin surface.” It is included along with the Herpetic herbs, those that are healing to skin eruptions which relate to the herpes virus and scaling diseases such as ringworm etc. It is also rubefacient, stimulant, and narcotic.
Herbal Remedies by Dr. John. R Christopher 
- Plantain (Plantago spp.) – Make a poultice of the fresh, bruised leaves and apply to the rash. Change before the poultice dries out.
- Sassafras (Sassafras albidum) – Use the infusion internally and with frequent external applications as a wash.
- Slippery Elm (Ulmus fulva) – Applied topically as a component of Dr. Christopher’s Asthma Remedy.
- Lobelia (Lobelia inflata) – Apply as a poultice – 1 part lobelia to 2 parts slippery elm.
- Virginia Snake Root (Aristolochia serpentaria) – Apply a wash of the fluid extract.
“Mrs. Maud Grieve was the Principal and Founder of ‘The Whins’ Medicinal and Commercial Herb School and Farm at Chalfont St. Peter in Buckinghamshire, England. The training school gave tuition and practical courses in all branches of herb growing, collecting, drying and marketing. Grieve had also been President of the British Guild of Herb Growers, and Fellow of the British Science Guild. Her work A Modern Herbal contains medicinal, culinary, cosmetic and economic properties, cultivation and folklore of herbs.”
Herbal Remedies by Mrs. M Grieve, F.R.H.S. 
- Alkaline lotions – Baking soda in baths and pastes, hyposulphite of soda – use to moisten skin frequently.
- Vervain Root (Verbena spp.) – Boiled in milk and water with the inner bark of the White Oak (Quercus alba).
Dr. John Heinerman traveled the world to work with folk healers and top doctors and scientists. Here are some of his suggestions to ease the pain of poison ivy.
Herbal Remedies by Dr. John Heinerman 
- Beech (Fagus grandifolia) – Steep bits of tree bark from the North side of the tree in 2 C slightly salted hot water until color is dark. Bathe affected rash as needed.
- Cattail (Typha Latifolia) – Make a paste of the root powder, spread a thin layer on rash, change after several hours.
- Goldenseal (Hydrastis canadensis) – 1 TSP powdered root to 1 pint hot water. Dab on rash. Taking internally is beneficial as well. NOTE: If possible, use the other remedies as Goldenseal is overharvested.
- Jewelweed (Impatiens pallida) – Rinse and crush well. Rub over affected areas. NOTE: Jewelweed is often found growing in the same location as poison ivy. Look for it as it should be used right away as an antidote for the urushiol.
- Solomon’s Seal (Polygonatum multiflorum) – Dig and clean fresh root, then hammer to a pulp. Apply a poultice of mashed root and leave for 24 hours or boil 1 C chopped root in 1-1/2 pints distilled water, covered, for 15 minutes, cool, strain, and wash skin with the tea.
- Sumac (Rhus glabra) – Make sure you have identified the correct species! Add 1 TBSP each of the bark, leaves, and berries to 1 Qt boiling water. Simmer covered for 30 minutes, then steep for 30 minutes, strain, refrigerate. Once cool, use as a wash.
~ Homeopathic Rhus Toxicondendron ~
- Itching Skin Diseases – Use the homeopathic both internally and externally for poison ivy/oak/sumac, rashes, ringworm, etc. Homeopathic Rhus Tox is also utilized to prevent/lesson an allergic reaction and to treat a rash.
~ Homeopathic Cell Salts ~
- Natrum Muriaticom & Kali Sulphuricum – For topical use only. Both must be used together. Use either the 3X or 6X potencies. Add to cool/lukewarm water, then apply directly to the rash using a clean cloth.
Due to its potent actions and the risk of toxicity, use of poison ivy as a medicinal has fallen by the wayside. Poison ivy was included as a remedy in the Merck Manual of 1899 as was Rhus Toxicondendron, the homeopathic. A fluid extract can be prepared from the fresh leaves, however, if taken orally a blistering rash may occur internally. With so many more suitable herbs, an herbalist would have no difficulty finding another to replace any potential benefit of Toxicodendron radicans.
Most skin rashes caused by urushiol are limited and cause only a minor although very irritating, sometimes painful, hot, itchy rash anywhere from five days to a few weeks.
It is important to not attempt to burn poison ivy as the oils are carried in the smoke and upon inhalation, can cause internal damage to the esophagus and the lining of the lungs. This condition is extremely painful and potentially deadly.
Should too great “a portion of the body be covered with blisters, respiration and excretion of poisonous wastes through the pores is impeded. This, in turn, may lead to a fatal toxemia.” The remedies included here are only intended for use with non-life-threatening conditions.
Hopefully, becoming knowledgeable helps us to avoid this beautiful-but-o-so-irritating plant. In the event that poison ivy makes itself known, we are now also armed with remedies to prevent and deal with the rash. Do you use natural remedies for poison ivy, poison oak or poison sumac? Tell us about them in the comments below.
Enjoy the outdoors this year!
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
- No Ill Nature: The Surprising History and Science of Poison Ivy and Its Relatives
- Investigation into the Phytochemical Composition of Poison Ivy and its Antimicrobial Activity by Hinchong Hanse, Mondeep Gogoi, Pronot Langthasa, Elufer Akram, Priya Islam, Taku Oniya
- From Leaf to Itch by Alvin Powell, Harvard Staff Writer
- The Truths and Myths About Poison Ivy, Poison Oak and Poison Sumac
- School of Natural Healing by Dr. John R. Christopher
- Collection of material relating to Mrs. Maud Grieve, F.R.H.S (fl.1937)
- A Modern Herbal by Mrs. Maud Grieve, F.R.H.S.
- Heinerman’s Encyclopedia of Healing Herbs & Spices by Dr. John Heinerman
- The Healing Echo Discovering Homeopathic Cell Salts by Vinton McCabe
- What Causes the “Itch” in Poison Ivy? Journal of the Franklin Institute, vol. 255, no. 3, pp.266-267