Editing Toxicodendron radicans

{{Short description|Species of plant}}
{{Speciesbox
|name = 
|image = 2014-10-29 13 43 39 Poison Ivy foliage during autumn leaf coloration in Ewing, New Jersey.JPG
|image_caption = During autumn
|image2 =Toxicodendron radicans, leaves.jpg
|image2_caption = In spring, [[Ottawa]], [[Ontario]]
|image2_alt = Photograph of green poison ivy leaves
|status=LC
|status_system=IUCN3.1
|status_ref=<ref name=iucnredlist>{{cite iucn|author1=Bárrios, S.|author2=Copeland, A.|name-list-style=amp|year=2021|title=''Toxicodendron radicans''|page=e.T124270453A192137361|doi=10.2305/IUCN.UK.2021-3.RLTS.T124270453A192137361.en|access-date=26 September 2023}}</ref>
|status2 = G5
|status2_system = TNC
|status2_ref=<ref>{{cite web|url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.152689/Toxicodendron_radicans|title=''Toxicodendron radicans''|website=NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer|author=NatureServe|publisher=NatureServe|location=Arlington, Virginia|date=1 September 2023|access-date=26 September 2023}}</ref>
|genus = Toxicodendron
|species = radicans
|authority =  (L.) Kuntze
|range_map = Eastern Poison Ivy Range.png
|range_map_caption = ''Toxicodendron radicans'' range map in the United States and Canada
|synonyms =
*''Rhus radicans'' {{au|L.}}
*''Rhus verrucosa'' {{au|Scheele, syn of subsp. verrucosum}}
}}

'''''Toxicodendron radicans''''', commonly known as '''eastern poison ivy'''<ref>{{PLANTS|id=TORA2|taxon=Toxicodendron radicans|access-date=11 December 2015}}</ref> or '''poison ivy''', is a species of allergenic [[flowering plant]]. It has numerous subtaxons and forms both vines and shrubs. Despite its common name, it is not a true [[ivy]], but rather a member of the [[cashew]] and [[pistachio]] family [[Anacardiaceae]]. It is different from western poison ivy, ''[[Toxicodendron rydbergii]]'', and resembles a number of species.

The species is found in North America. Although commonly eaten by animals, with birds consuming the seeds, ''T.&nbsp;radicans'' is considered a [[noxious weed]]. As a [[poison ivy]], it causes [[urushiol-induced contact dermatitis]] in most people who touch it, producing an itchy, irritating, and sometimes painful rash.

== Description ==
Numerous [[subspecies]] and/or [[Variety (botany)|varieties]] of ''T.Toxicodendron rydbergii radicans'' are known.<ref name="WeeksJr.2012">{{cite book|author1=Weeks, Sally S. |author2=Weeks, Harmon P. Jr.|title=Shrubs and Woody Vines of Indiana and the Midwest: Identification, Wildlife Values, and Landscaping Use|url=https://books.google.com/books?id=O-S6uVDWTjoC&pg=PA356|date= 2012|publisher=Purdue University Press|isbn=978-1-55753-610-5|pages=356–}}</ref> They can be found growing in any of the following forms, all having woody stems:

* as a climbing [[vine]] that grows on [[tree]]s or some other support
* as a [[shrub]] up to {{convert|1.2|m|ft|abbr=off|frac=2}} tall
* as a trailing vine that is {{convert|10|–|25|cm|abbr=off|0}} tall

The [[deciduous]] [[leaves]] of ''T.&nbsp;radicans'' are [[trifoliate]] with three [[almond]]-shaped [[leaflet (botany)|leaflets]].<ref name=feis>{{FEIS |title=Toxicodendron radicans, T. rydbergii |genus=Toxicodendron |type=shrub |last=Innes |first=Robin J. |date=2012}}</ref> Leaf color ranges from light green (usually the younger leaves) to dark green (mature leaves), turning bright red in [[Autumn|fall]]; though other sources say leaves are reddish when expanding, turn green through maturity, then back to red, orange, or yellow in the fall. The leaflets of mature leaves are somewhat shiny. The leaflets are {{convert|3|-|12|cm|in|abbr=on|frac=4}} long, rarely up to {{convert|30|cm|in|abbr=on}}. Each leaflet has a few or no teeth along its edge, and the leaf surface is smooth. Leaflet clusters are [[alternate leaf|alternate]] on the vine, and the plant has no thorns. Vines growing on the trunk of a tree become firmly attached through numerous aerial rootlets.<ref>{{cite book |last=Petrides |first=George A. |title=A Field Guide to Trees and Shrubs'' (Peterson Field Guides)'' |place=Boston |publisher=Houghton Mifflin |date=1986 |page=130 }}</ref> The vines develop [[adventitious roots]], or the plant can spread from [[rhizome]]s or [[root crown]]s. The milky sap of poison ivy darkens after exposure to the air.

''T. radicans'' spreads either [[Vegetative reproduction|vegetatively]] or [[plant sexuality|sexually]]. It is [[dioecious]]; flowering occurs from May to July. The yellowish- or greenish-white flowers are typically inconspicuous and are located in clusters up to {{convert|8|cm|in|abbr=on|0}} above the leaves. The berry-like fruit, a [[drupe]], mature by August to November with a grayish-white colour.<ref name="feis" /><gallery>
File:Poison ivy vine.jpg|''T. radicans'' vine with typical reddish "hairs"
File:Poison Ivy in Perrot State Park.jpg|''T. radicans'' in [[Trempealeau County, Wisconsin]]
File:Toxicodendron radicans 01.jpg|Flower detail, with bee
File:Poison ivy-roadside.jpg|Poison ivy on a roadside
File:Poison ivy in May beside Appalachian Trail in Rockfish Gap VA area 1.jpg|Leaves may be smooth or notched on the same plant.
File:Rhus radicans 006.jpg|In [[Batiscan, Quebec]], Canada
</gallery>

=== Identification ===
These four characteristics are sufficient to identify poison ivy in most situations: (a) clusters of three leaflets, (b) alternate leaf arrangement, (c) lack of thorns, and (d) each group of three leaflets grows on its own stem, which connects to the main vine, the middle stem is longer.<ref>Illustration, What does poison ivy look like? A simple guide to identifying poison ivy in the wild. [https://www.greenbelly.co/pages/how-to-identify-poison-ivy]</ref> The appearance of poison ivy can vary greatly among environments, and even within a large area. Identification by experienced people is often made difficult by leaf damage, the plant's leafless condition during winter, and unusual growth forms due to environmental or genetic factors. Various [[mnemonic]] rhymes describe the characteristic appearance of poison ivy:<ref>{{cite web |title=Poison Ivy Treatment Guide, Getting Rid of the Plants: Identifying Poison Ivy |url=http://pediatrics.about.com/cs/conditions/a/poison_ivy_3.htm |access-date=2009-07-21 |archive-date=2011-01-10 |archive-url=https://web.archive.org/web/20110110183549/http://pediatrics.about.com/cs/conditions/a/poison_ivy_3.htm |url-status=dead }}</ref>

# "Leaves of three, let it be" is the best known and most useful cautionary rhyme. It applies to [[poison oak]], as well as to poison ivy. However, some other innocuous plants have similar leaves.<ref name="Crosby2004">{{cite book |author=Crosby, Donald G. |url=https://books.google.com/books?id=W4D1H1PEL-AC&pg=PA32 |title=The Poisoned Weed: Plants Toxic to Skin |publisher=Oxford University Press |year=2004 |isbn=978-0-19-515548-8 |pages=32–}}</ref>
# "Hairy vine, no friend of mine"<ref name="Jennings2010">{{cite book |author=Jennings, Neil L. |url=https://books.google.com/books?id=BuUCxztT6ycC&pg=PA105 |title=In Plain Sight: Exploring the Natural Wonders of Southern Alberta |publisher=Rocky Mountain Books Ltd |year=2010 |isbn=978-1-897522-78-3 |pages=105–}}</ref>
# "Berries white, run in fright" and "Berries white, danger in sight"<ref name="Jennings2010" />

<gallery widths="200px" heights="160px">
File:Poison Ivy warning sign.jpg|Poison ivy warning
File:Red River Gorge - Poison Ivy.jpg|''T. radicans'' leaf and berries
File:Toxicodendron_radicans_Foliage.JPG|''T. radicans'' foliage
</gallery>

==== Similar-looking plants ====
* Box elder (''[[Acer negundo]]'') saplings have leaves that can look very similar to those of poison ivy, although the [[symmetry]] of the plant itself is very different. While box elders often have five or seven leaflets, three leaflets are also common, especially on smaller saplings. The two can be differentiated by observing the placement of the leaves where the leaf stalk meets the main branch (where the three leaflets are attached). Poison ivy has alternate leaves, which means the three-leaflet leaves alternate along the main branch. Boxelder has [[opposite leaves]]; another leaf stalk directly on the opposite side is characteristic of box elder.
* Virgin's bower (''[[Clematis virginiana]]'') is a vine of the [[buttercup family]] native to eastern North America. This vine can climb up to {{convert|10|–|20|ft|m}} tall. It grows on the edges of the woods, moist slopes, and fence rows, and in thickets and streambanks. It produces white, fragrant flowers about {{convert|1|in|cm}} in diameter between July and September.
* Virginia creeper (''[[Parthenocissus quinquefolia]]'') vines can look like poison ivy. The younger leaves can consist of three leaflets but have a few more serrations along the leaf edge, and the leaf surface is somewhat wrinkled. However, most Virginia creeper leaves have five leaflets. Virginia creeper and poison ivy very often grow together, even on the same tree. Even those who do not get an allergic reaction to poison ivy may be allergic to the oxalate crystals in Virginia creeper sap.
* Western poison oak (''[[Toxicodendron diversilobum]]'') leaflets also grow in threes on the end of a stem, but each leaflet is shaped somewhat like an [[oak]] leaf. Western poison oak grows only in western North America, although many people refer to poison ivy as poison oak, because poison ivy grows in either the ivy-like form or the brushy oak-like form depending on the moisture and brightness of its environment. The ivy form likes shady areas with only a little sun, tends to climb the trunks of trees, and can spread rapidly along the ground.
*Poison sumac (''[[Toxicodendron vernix]]'') has compound leaves with 7–15 leaflets. Poison sumac never has only three leaflets.
* [[Kudzu]] (''Pueraria lobata'') is a nontoxic edible vine that scrambles extensively over lower vegetation or grows high into trees. Kudzu is an [[invasive species]] in the southern United States. Like poison ivy, it has three leaflets, but the leaflets are bigger than those of poison ivy and are [[Leaf#Surface of the leaf|pubescent]] underneath with hairy margins.
* [[Blackberries]] and [[raspberries]] (''Rubus'' spp.) can resemble poison ivy, with which they may share territory; however, blackberries and raspberries almost always have thorns on their stems, whereas poison ivy stems are smooth. Also, the three-leaflet pattern of some blackberry and raspberry leaves changes as the plant grows: Leaves produced later in the season have five leaflets rather than three. Blackberries and raspberries have many fine teeth along the leaf edge, the top surface of their leaves is very wrinkled where the veins are, and the bottom of the leaves is light minty-greenish white. Poison ivy is all green. The stem of poison ivy is brown and cylindrical, while blackberry and raspberry stems can be green, can be squared in cross-section, and can have prickles. Raspberries and blackberries are never truly vines; they do not attach to trees to support their stems.
* [[Strawberries]] (''[[Fragaria]]''), wild or cultivated, have trifoliate leaves and a red vine, and can be found in similar ecosystems. However, strawberry leaflets are serrated and have same-length petiolules. The stems also have small trichomes, which poison ivy lacks.
* The thick vines of [[Vitis riparia|riverbank grape]] (''Vitis riparia''), with no rootlets visible, differ from the vines of poison ivy, which have so many rootlets that the stem going up a tree looks furry. Riverbank grapevines are purplish in color, tend to hang away from their support trees, and have shreddy bark; poison ivy vines are brown, attached to their support trees, and do not have shreddy bark.
* Fragrant sumac (''[[Rhus aromatica]]'') has a very similar appearance to poison ivy. While both species have three leaflets, the center leaflet of poison ivy is on a long stalk, while the center leaflet of fragrant sumac does not have an obvious stalk. When crushed, fragrant sumac leaves have a fragrance similar to citrus, while poison ivy has little or no distinct fragrance. Fragrant sumac produces flowers before the leaves in spring, while poison ivy produces flowers after the leaves emerge. Flowers and fruits of fragrant sumac are at the end of the stem but occur along the middle of the stem of poison ivy. Fragrant sumac fruit ripens to a deep reddish color and is covered with tiny hairs, while poison ivy fruit is smooth and ripens to a whitish color.
* Hoptree (''[[Ptelea trifoliata]]'') has leaves that are remarkably similar. It is, however, a much larger plant, so confusion is unlikely for any but the smallest specimens. The flowers and seeds are also easily distinguished from those of poison ivy.

==== Similar allergenic plants ====
*''[[Toxicodendron rydbergii]]'' (western poison ivy)
*''[[Smodingium argutum]]'' (African poison ivy)
*''[[Toxicodendron pubescens]]'' (poison oak – eastern)
*''[[Toxicodendron diversilobum]]'' (poison oak – western)
*''[[Toxicodendron vernix]]'' (poison sumac)
*''[[Gluta]] spp'' (rengas tree)
*''[[Toxicodendron vernicifluum]]'' (Japanese lacquer tree)
*''[[Lithraea molleoides]]'' (''aruera'' – South America)<ref>{{cite web |title=Botanical Dermatology – ALLERGIC CONTACT DERMATITIS – ANACARDIACEAE AND RELATED FAMILIES |url=http://www.telemedicine.org/botanica/bot6.htm |access-date=22 Sep 2014 |website=The Internet Dermatology Society, Inc}}</ref>

== Taxonomy ==
;Subspecies<ref>{{PLANTS|symbol=TORA2|taxon=Toxicodendron radicans}}</ref><ref>[http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:255769-2#children ''Toxicodendron radicans'' (L.) Kuntze]. Plants of the World Online. cience.kew.org</ref><ref name="FOC">{{Cite book |last1=Min |first1=Tianlu |url=http://flora.huh.harvard.edu/china/mss/volume11/Anacardiaceae.pdf |title=Flora of China |last2=Barfod |first2=Anders |publisher=Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis |year=2008 |editor-last=Wu |editor-first=Z. Y. |volume=11 (Oxalidaceae through Aceraceae) |chapter=Flora of China: Anacardiaceae |editor-last2=Raven |editor-first2=P. H. |editor-last3=Hong |editor-first3=D. Y.}}</ref>
*''T. r.'' subsp. ''barkleyi'' <small>Gillis</small>
*''T. r.'' subsp. ''divaricatum'' <small>(Greene) Gillis</small>
*''T. r.'' subsp. ''eximium'' <small>(Greene) Gillis</small>
*''T. r.'' subsp. ''hispidum'' <small>(Greene) Gillis</small>
*''T. r.'' subsp. ''negundo'' <small>(Greene) Gillis</small>
*''T. r.'' subsp. ''pubens'' <small>(Engelm. ex S. Watson) Gillis</small>
*''T. r.'' subsp. ''radicans''
*''T. r.'' subsp. ''verrucosum'' <small>(Scheele) Gillis</small>
''Caquistle'' or ''caxuistle'' is the [[Nahuatl]] term for the species.

== Distribution and habitat ==
''T. radicans'' grows throughout much of [[North America]], including the Canadian [[Maritime provinces]], [[Quebec]], [[Ontario]], and all US states east of the [[Rocky Mountains]],<ref>{{BONAP |genus=Toxicodendron |species=radicans |date=2014}}</ref> as well as in the mountainous areas of Mexico<ref name="feis" /> up to around {{convert|1500|m|ft|abbr=on}}.<ref name=iucnredlist/> It is normally found in wooded areas, especially along edge areas where the tree line breaks and allows sunshine to filter through. It also grows in exposed rocky areas, open fields, and disturbed areas.

It may grow as a [[forest]] [[understory]] plant, although it is only somewhat [[shade-tolerant]].<ref name="feis" /> The plant is extremely common in suburban and exurban areas of [[New England]], the [[Mid-Atlantic states|Mid-Atlantic]], and the [[Southeastern United States]]. The similar species ''[[Toxicodendron diversilobum|T.&nbsp;diversilobum]]'' (western poison oak) and ''[[Toxicodendron rydbergii|T.&nbsp;rydbergii]]'' (western poison ivy) are found in western North America, and ''[[Toxicodendron orientale|T.&nbsp;orientale]]'' in Taiwan, Japan, Korea and Sakhalin.

''T. radicans'' rarely grows at altitudes above {{convert|1500|m|ft|abbr=on}}, although the altitude limit varies in different locations.<ref name="feis" /> The plants can grow as a shrub up to about {{convert|1.2|m|ft|abbr=on|frac=2}} tall, as a [[groundcover]] {{convert|10|-|25|cm|in|abbr=on|frac=2}} high, or as a climbing vine on various supports. Older vines on substantial supports send out lateral branches that may be mistaken for tree limbs at first glance.

It grows in a wide variety of [[soil]] types, and [[soil pH]] from 6.0 ([[acid]]ic) to 7.9 (moderately [[alkaline]]). It is not particularly sensitive to [[soil moisture]], although it does not grow in [[desert]] or [[arid]] conditions. It can grow in areas subject to seasonal [[flooding]] or [[brackish water]].<ref name="feis" />

It is more common now than when Europeans first arrived in North America. The development of real estate adjacent to wild, undeveloped land has engendered "[[edge effect]]s", enabling poison ivy to form vast, lush colonies in these areas. It is listed as a [[noxious weed]] in the US states of [[Minnesota]] and [[Michigan]] and in the Canadian province of Ontario.

Poison ivy is particularly sensitive to [[carbon dioxide]] levels, greatly benefiting from higher concentrations in the atmosphere. Higher carbon dioxide levels increase the rate of plant growth, and cause them to produce more unsaturated urushiol, which causes stronger reactions in humans.<ref>{{cite journal |doi=10.1073/pnas.0602392103 |pmid=16754866 |pmc=1474014 |title=Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO<sub>2</sub> |journal=Proceedings of the National Academy of Sciences |date= 2006|first1=Jacqueline E. |last1=Mohan |first2=Lewis H. |last2=Ziska |first3=William H. |last3=Schlesinger |first4=Richard B. |last4=Thomas |first5=Richard C. |last5=Sicher |first6=Kate |last6=George |first7=James S. |last7=Clark |volume=103 |issue=24 |pages=9086–9089|bibcode=2006PNAS..103.9086M |doi-access=free }}</ref> Poison ivy's growth and potency has already doubled since the 1960s, and it could double again once carbon dioxide levels reach 560 ppm.<ref name="gazette">{{cite news|author=Templeton|first=David|date=July 22, 2013|title=Climate change is making poison ivy grow bigger and badder|url=https://www.post-gazette.com/news/health/2013/07/22/Climate-change-is-making-poison-ivy-grow-bigger-and-badder/stories/201307220149|url-status=live|archive-url=https://web.archive.org/web/20210726190537/https://www.post-gazette.com/news/health/2013/07/22/Climate-change-is-making-poison-ivy-grow-bigger-and-badder/stories/201307220149|archive-date=July 26, 2021|access-date=July 23, 2013|work=[[Pittsburgh Post-Gazette]]}}</ref>
== Ecology ==
The fruits are a favorite winter food of some birds and other animals, including wild [[Turkey (bird)|turkey]]s.<ref>{{Cite book |last=Dickson |first=James G. |url=https://books.google.com/books?id=oVICEKm1U04C&pg=PA72 |title=The Wild Turkey: Biology and Management |date=1992 |publisher=Stackpole Books |isbn=978-0-8117-1859-2 |language=en}}</ref><ref name="Professor2005">{{cite book |author=Department of Biology Hamilton College Ernest H. Williams Jr. Professor |url=https://books.google.com/books?id=VoV7CclhNJcC&pg=PA57 |title=The Nature Handbook: A Guide to Observing the Great Outdoors: A Guide to Observing the Great Outdoors |date=26 April 2005 |publisher=Oxford University Press |isbn=978-0-19-972075-0 |pages=57–}}</ref> Seeds are [[Zoochory|spread mainly by animals]] and remain viable after passing through the digestive tract.  Birds may spread the seeds by [[Regurgitation (digestion)|regurgitation]].<ref>{{Cite book |last=Crafts |first=Alden S. |url=https://books.google.com/books?id=QCboDwAAQBAJ&pg=PA25 |title=Modern Weed Control |date=2021-01-08 |publisher=Univ of California Press |isbn=978-0-520-31742-0 |language=en}}</ref>

== Toxicity ==
[[File:How Poison Ivy Works.webm|thumb|upright=1.3|A video describing the effects of poison ivy on the body]]
[[File:Urushiol induced contact dermatitis.jpg|thumb|upright=1.3|[[Blister]]s from contact with poison ivy]]
{{Main|Urushiol-induced contact dermatitis}}
Urushiol-induced contact dermatitis is the [[allergy|allergic reaction]] caused by poison ivy. In extreme cases, a reaction can progress to [[anaphylaxis]]. Around 15 to 25 percent of people have no allergic reaction to urushiol, but most people have a greater reaction with repeated or more concentrated exposure.<ref name="hsw">{{cite web|url=http://science.howstuffworks.com/poison-ivy.htm|title=How Poison Ivy Works|work=HowStuffWorks|date=23 September 2005}}</ref><ref>{{cite web|url=http://mic-ro.com/plants/|title=Contact-Poisonous Plants of the World|author=Rohde, Michael|work=mic-ro.com|access-date=2004-06-12|archive-date=2010-07-02|archive-url=https://web.archive.org/web/20100702160140/http://mic-ro.com/plants/|url-status=dead}}</ref> Typically, the rash from the urushiol oil lasts about five to twelve days, but in extreme cases, it can last a month or more.<ref>{{cite web|url=https://www.gemplers.com/tech/faq-poison-ivy.htm|title=Poison Ivy, Poison Oak and Poison Sumac FAQs}}</ref>

Over 350,000 people are affected by urushiol annually in the United States.<ref>{{cite news|last=Chaker|first=Anne Marie|title=Least-Welcome Sign of Summer|newspaper=[[The Wall Street Journal]]|date=June 22, 2010|author2=Athavaley, Anjali|page=D1}}</ref>

The pentadecyl [[catechols]] of the [[oleoresin]] within the sap of poison ivy and related plants causes the allergic reaction; the plants produce a mixture of pentadecylcatechols, which collectively is called urushiol. After injury, the sap leaks to the surface of the plant where the urushiol becomes a blackish [[lacquer]] after contact with oxygen.<ref name="Barceloux2008">{{cite book |author=Barceloux, Donald G. |url=https://books.google.com/books?id=CpqzhHc072AC&pg=PA681 |title=Medical Toxicology of Natural Substances: Foods, Fungi, Medicinal Herbs, Plants, and Venomous Animals |publisher=John Wiley and Sons |year=2008 |isbn=978-0-471-72761-3 |pages=681–}}</ref><ref name="RietschelFowler2008">{{cite book|author1=Rietschel, Robert L. |author2=Fowler, Joseph F. |author3=Fisher, Alexander A. |title=Fisher's contact dermatitis|url=https://books.google.com/books?id=dQBAzfyCeQ8C&pg=PA408|year=2008|publisher=PMPH-USA|isbn=978-1-55009-378-0|pages=408–}}</ref>

Urushiol binds to the skin on contact, where it causes severe itching that develops into reddish inflammation or uncoloured bumps, and then [[blister]]ing. These [[lesions]] may be treated with [[Calamine]] lotion, [[Burow's solution]] compresses, dedicated commercial poison ivy itch creams, or baths to relieve discomfort,<ref>Wilson, W. H. & Lowdermilk, P. (2006). Maternal Child Nursing Care (3rd edition). St. Louis: Mosby Elsevier.</ref> though recent studies have shown some traditional medicines to be ineffective.<ref>{{cite web |url=http://www.iht.com/articles/1992/09/09/topi.php |title=American Topics. An Outdated Notion, That Calamine Lotion |access-date=2007-07-19 |archive-url = https://web.archive.org/web/20070619004539/http://www.iht.com/articles/1992/09/09/topi.php <!-- Bot retrieved archive --> |archive-date = 2007-06-19}}</ref><ref>{{cite journal | last1 = Appel | first1 = L.M. Ohmart | last2 = Sterner | first2 = R.F. | year = 1956 | title = Zinc oxide: A new, pink, refractive microform crystal | journal = AMA Arch Dermatol | volume = 73 | issue = 4| pages = 316–324 | doi = 10.1001/archderm.1956.01550040012003 | pmid = 13301048 }}</ref> [[Over-the-counter]] products to ease itching—or simply oatmeal baths and [[baking soda]]—are now recommended by [[dermatologists]] for the treatment of poison ivy.<ref>{{cite web |url=http://www.aad.org/public/publications/pamphlets/skin_poison.html |title=American Academy of Dermatology – Poison Ivy, Oak & Sumac |url-status=dead |archive-url=https://web.archive.org/web/20090605182107/http://www.aad.org/public/publications/pamphlets/skin_poison.html |archive-date=2009-06-05 }}</ref>

A plant-based remedy cited to counter urushiol-induced contact dermatitis is [[Impatiens|jewelweed]], though jewelweed extracts had no positive effect in clinical studies.<ref>{{cite journal | last1 = Long | first1 = D. | last2 = Ballentine | first2 = N. H. | last3 = Marks | first3 = J. G. | year = 1997 | title = Treatment of poison ivy/oak allergic contact dermatitis with an extract of jewelweed. | journal = Am. J. Contact. Dermat | volume = 8 | issue = 3| pages = 150–3 | pmid = 9249283 | doi=10.1097/01206501-199709000-00005}}</ref><ref>{{cite journal | last1 = Gibson | first1 = MR | last2 = Maher | first2 = FT | title = Activity of jewelweed and its enzymes in the treatment of Rhus dermatitis. | journal = Journal of the American Pharmaceutical Association | volume = 39 | issue = 5 | pages = 294–6 | year = 1950 | pmid = 15421925 | doi=10.1002/jps.3030390516}}</ref><ref>{{cite journal | last1 = Guin | first1 = J. D. | last2 = Reynolds | first2 = R. | year = 1980 | title = Jewelweed treatment of poison ivy dermatitis. | journal = Contact Dermatitis | volume = 6 | issue = 4| pages = 287–8 | doi = 10.1111/j.1600-0536.1980.tb04935.x | pmid = 6447037 | s2cid = 46551170 }}</ref><ref>{{cite journal | last1 = Zink | first1 = B. J. | last2 = Otten | first2 = E. J. | last3 = Rosenthal | first3 = M. | last4 = Singal | first4 = B. | year = 1991 | title = The effect of jewel weed in preventing poison ivy dermatitis| journal = Journal of Wilderness Medicine | volume = 2 | issue = 3 | pages = 178–182 | doi = 10.1580/0953-9859-2.3.178 | s2cid = 57162394 }}</ref> Others argue that prevention of lesions is easy if one practices effective washing, using plain soap, scrubbing with a washcloth, and rinsing three times within 2–8 hours of exposure.<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211211/4oyoDRHpQK0 Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20140625003135/https://www.youtube.com/watch?v=4oyoDRHpQK0 Wayback Machine]{{cbignore}}: {{Cite web|author=Extreme Deer Habitat|title=How to never have a serious poison ivy rash again|website=[[YouTube]]|date=2014-06-22|url=https://www.youtube.com/watch?v=4oyoDRHpQK0|access-date=2016-07-26}}{{cbignore}}</ref>

The oozing fluids released by scratching blisters do not spread the poison. The fluid in the blisters is produced by the body and it is not urushiol itself.<ref name=faq/> The appearance of a spreading rash indicates that some areas received more of the poison and reacted sooner than other areas or that contamination is still occurring from contact with objects to which the original poison was spread. Those affected can unknowingly spread the urushiol inside the house, on phones, doorknobs, couches, counters, desks, and so on, thus in fact repeatedly coming into contact with poison ivy and extending the length of time of the rash. If this has happened, wipe down the surfaces with bleach or a commercial urushiol removal agent. The blisters and oozing result from blood vessels that develop gaps and leak fluid through the skin; if the skin is cooled, the vessels constrict and leak less.<ref name="Prevention2010">{{cite book|author=((Editors of Prevention))|title=The Doctors Book of Home Remedies: Quick Fixes, Clever Techniques, and Uncommon Cures to Get You Feeling Better Fast|url=https://books.google.com/books?id=ExFziuyaXWcC&pg=PA488|date= 2010|publisher=Rodale|isbn=978-1-60529-866-5|pages=488–}}</ref> If plant material with urushiol is burned and the smoke then inhaled, this rash will appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty.<ref name=faq/> If poison ivy is eaten, the mucous lining of the mouth and digestive tract can be damaged.<ref name="Lewis1998">{{cite book|author=Lewis, Robert Alan |title=Lewis' dictionary of toxicology|url=https://books.google.com/books?id=caTqdbD7j4AC&pg=PA901|year=1998|publisher=CRC Press|isbn=978-1-56670-223-2|pages=901–}}</ref> An urushiol rash usually develops within a week of exposure and can last 1–4 weeks, depending on severity and treatment. In rare cases, urushiol reactions may require hospitalization.<ref name=faq>{{cite web |url=http://www.poison-ivy.org/html/faq.htm |title=Facts about Poison Ivy: How long does the rash last?, What can you do once the itching starts?, How do you get poison ivy? |website=poison-ivy.org |date=25 February 2015 |access-date=21 July 2009 |archive-date=30 June 2010 |archive-url=https://web.archive.org/web/20100630183437/http://www.poison-ivy.org/html/faq.htm |url-status=dead }}</ref>

Urushiol oil can remain active for several years, so handling dead leaves or vines can cause a reaction. In addition, oil transferred from the plant to other objects (such as pet fur) can cause the rash if it comes into contact with the skin.<ref>{{cite web|url=http://www.aad.org/public/Publications/pamphlets/Poison_IvyOakSumac.htm|title=Poison Ivy, Oak & Sumac|work=aad.org|url-status=dead|archive-url=https://web.archive.org/web/20070708105008/http://www.aad.org/public/Publications/pamphlets/Poison_IvyOakSumac.htm|archive-date=2007-07-08}}</ref><ref name=faq/> Clothing, tools, and other objects that have been exposed to oil should be washed to prevent further reactions.<ref>{{cite web |title=Poison ivy - oak - sumac |url=https://medlineplus.gov/ency/article/002886.htm |website=MedlinePlus Medical Encyclopedia |publisher=[[A.D.A.M., Inc.]] |access-date=16 June 2019}}</ref>

People who are sensitive to urushiol can also experience a similar rash from [[mangoes]]. Mangoes are in the same family (Anacardiaceae) as poison ivy; the sap of the mango tree and skin of mangoes has a chemical compound similar to urushiol.<ref>{{cite journal|doi=10.1056/NEJM199807233390405|pmid=9673302|title=The Mango–Poison Ivy Connection|journal=New England Journal of Medicine|volume=339|issue=4|pages=235|year=1998|last1=Tucker|first1=Mark O.|last2=Swan|first2=Chad R.}}</ref> A related allergenic compound is present in the raw shells of [[cashew]]s.<ref name="Rosen">{{cite journal
 |last = Rosen |first = T. |author2=Fordice, D. B.
  |title = Cashew Nut Dermatitis |journal = Southern Medical Journal | volume = 87 | issue = 4
 |pages = 543–546 |date = April 1994|doi = 10.1097/00007611-199404000-00026| pmid = 8153790 }}</ref> Similar reactions have been reported occasionally from contact with the related Fragrant Sumac (''[[Rhus aromatica]]'') and [[Toxicodendron vernicifluum|Japanese lacquer tree]].{{citation needed|date=September 2021}} These other plants are also in the family Anacardiaceae.

=== Treatment ===
{{Main|Urushiol-induced contact dermatitis#Treatments}}

Immediate washing with soap and cold water or [[rubbing alcohol]] may help prevent a reaction.<ref>{{cite web|url=http://www.teclabsinc.com/blog/2012/8/2/common-misconceptions-about-treating-poison-ivy-or-oak-rash|title=Misconceptions About Treating Poison Ivy and Oak Rash|work=teclabsinc.com|url-status=dead|archive-url=https://web.archive.org/web/20140826160923/http://www.teclabsinc.com/blog/2012/8/2/common-misconceptions-about-treating-poison-ivy-or-oak-rash|archive-date=2014-08-26}}</ref> During a reaction, Calamine lotion or [[diphenhydramine]] may help mitigate symptoms. [[Corticosteroid]]s, either applied to the skin or taken by mouth, may be appropriate in extreme cases. An astringent containing aluminum acetate (such as [[Burow's solution]]) may also provide relief and soothe the uncomfortable symptoms of the rash.<ref>{{cite journal|last1=Gladman|first1=Aaron C.|title=Toxicodendron Dermatitis: Poison Ivy, Oak, and Sumac|journal=Wilderness & Environmental Medicine|date=June 2006|volume=17|issue=2|pages=120–128|doi=10.1580/PR31-05.1|pmid=16805148|doi-access=free}}</ref>

== See also ==
* [[Pileolaria brevipes|Poison ivy rust]]

== References ==
{{Reflist}}

== External links ==
{{Commons|Toxicodendron radicans}}
*[http://www.botanical-dermatology-database.info/BotDermFolder/ANAC-1.html Anacardiaceae] in [http://www.botanical-dermatology-database.info/index.html BoDD – Botanical Dermatology Database]
* [https://web.archive.org/web/20060822050902/http://www.cas.vanderbilt.edu/bioimages/species/frame/tora2.htm ''Toxicodendron radicans'' images at bioimages. vanderbilt.edu]
* [http://www.omafra.gov.on.ca/english/crops/facts/99-015.htm Poison Ivy], Ontario Ministry of Agriculture, Food and Rural Affairs
* [https://weedscanada.ca/cashew.html Common weeds of the northern United States and Canada: Western poison oak, poison ivy and poison sumac. (Anacardiaceae-family)]
* [https://www.poison-ivy.org/ Large site with many photos, facts, products, rash images, and a quiz about poison ivy.]

{{Taxonbar|from=Q7218532}}
{{Authority control}}

[[Category:Allergology]]
[[Category:Dioecious plants]]
[[Category:Flora of Northern America]]
[[Category:Medicinal plants]]
[[Category:Toxicodendron|radicans]]
[[Category:Vines]]