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Poison Ivy

Scientific Name(s): Toxicodendron diversilobum (Torr. & A. Gray) Greene, Toxicodendron pubescens Mill., Toxicodendron radicans (L.) Kuntze, Toxicodendron rydbergii (Small ex Rydb.) Greene, Toxicodendron succedaneum (L.) Kuntze, Toxicodendron vernicifluum (Stokes) F.A. Barkley, Toxicodendron vernix (L.) Kuntze
Common Name(s): Chinese lacquer, Markweed, Poison dogwood, Poison elder, Poison ivy, Poison oak, Poison sumac

Clinical Overview

Use

Clinical trials are lacking to support therapeutic applications.

Dosing

Poison ivy preparations should not be ingested due to potential for allergy and toxicity. Desensitization is not generally successful.

Contraindications

Not considered safe for use.

Pregnancy/Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Contact dermatitis, including black-spot poison ivy dermatitis, is well recognized.

Toxicology

Clinical information is limited.

Botany

"Poison ivy" or "poison oak" refers to several members of the Toxicodendron genus (formerly Rhus), which grow throughout the United States. Identification of the exact species has traditionally relied on the adage "leaves of 3, let it be;" however, poison oak can have 3 to 5 leaflets and nonpoisonous sumac can have up to 13 leaflets. The nontoxic Virginia creeper (Parthenocissus quinquefolia) can also be mistaken for poison ivy.1, 2, 3

Images for identification are available on the US Department of Agriculture’s online PLANTS Database.1 Generally, all species have U- or V-shaped leaf scars (where the leaf breaks from the stem), and flowers and fruits arise in the axillary position (the angle between the leaf and the branch). A black deposit is often present when Toxicodendron has been injured. Following trauma, the toxic oleoresin exudes, darkens with exposure to air, and hardens, which may assist in identification.2 Synonyms of T. pubescens include Rhus acutiloba, Rhus toxicarium, Rhus toxicodendron, Toxicodendron quercifolium, and Toxicodendron toxicarium.

Chemistry

An oily phenolic resin, termed "lobinol" by James B. McNair of the University of Chicago in the 1920s,4 is present in all poisonous Toxicodendron species and contains urushiol, a complex active principle derived from the Japanese term "sap." Urushiol is a mixture of antigenic catechols closely related to 3-n-pentadecylcatechol (3- PDC, hydrourushiol), varying in degree of saturation and length of side chain,2, 5 and carried by resin canals in the bark, stem, leaflets, and certain flower parts. The relative percentages of 3-PDC and related catechols vary among the species and may be related to environmental conditions. The danger of toxicity is greatest in spring and summer when the sap is abundant, the urushiol content is high, and the plant is easily bruised.2 Other chemical compounds in poison ivy include fisetin, gallotannic acid, kaempferol, myricetin, quercetin, rhamnose, and tannins.5 Additionally, heneicosandicarbonic, myristic, and palmitic acids have been identified in the fruit, and linoleic and oleic acids in the seeds.5

The chemical composition of T. vernicifluum, and the lacquer sap/wax obtained from this species, is also under investigation, with polysaccharides, phenolic, and sesquiterpenoid compounds of interest.6, 7, 8, 9, 10

Uses and Pharmacology

Arthritis/Inflammation

Animal data

Flavonoids extracted from the Chinese T. vernicifluum species have been investigated in vitro for anti-inflammatory activity against cyclo-oxygenase and antioxidant action.11, 12

Anti-inflammatory activity has been described in rodent studies using homeopathic R. toxicodendron.13, 14, 15, 16, 17, 18 However, analytical documentation of the content and strength of the preparations used was not included.

Clinical data

A multicenter, randomized trial (N = 142) evaluated the homeopathic preparation Disci/Rhus toxicodendron compositum (a composite medication authorized in Germany) in low back pain. The homeopathic injection preparation (51 patients) was not superior to placebo injections (48 patients), but did result in clinically relevant pain relief in comparison to no treatment (51 patients).19

Dosing

Clinical applications are lacking. Poison ivy preparations should not be ingested due to potential for allergy and toxicity.20 Desensitization is not generally successful.2

Pregnancy / Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented. A delayed hypersensitivity reaction (Rhus allergic contact dermatitis) occurred in a patient taking etanercept.21

Adverse Reactions

Mild to severe allergic contact dermatitis, typically a pruritic, erythematous, and vesicular rash depending upon point of contact, is well documented. Black-spot poison ivy dermatitis has also been described, with characteristic black lesions.22, 23

Urushiol is degraded in water and immediate washing of the contact area with a detergent-containing or "grease-cutting" soap is advised.2 Findings from a randomized clinical study suggest that long courses (15 days, with tapering) of oral corticosteroid treatment are more beneficial than short courses (5 days).24 Contact dermatitis from homeopathic R. toxicodendron has been reported,25 as has dermatitis from ingestion of Rhus lacquer.26 The oleoresin urushiol appears to be allergenic only to humans and higher primates. Desensitization is not generally successful.2

Toxicology

Dose-dependent genotoxicity has been observed in bone marrow of mice exposed to an extract of T. pubescens (Atlantic poison oak).27

References

1. Toxicodendron radicans. USDA, NRCS. 2015 The PLANTS Database (http://plants.usda.gov/, March 2015). National Plant Data Center, Baton Rouge, LA 70874-4490 USA. Accessed April 18, 2015.
2. Gladman AC. Toxicodendron dermatitis: poison ivy, oak, and sumac. Wilderness Environ Med. 2006;17(2):120-128.16805148
3. Parkinson G. Images in clinical medicine. The many faces of poison ivy. N Engl J Med. 2002;347(1):35.12097538
4. McNair JB. Lobinol—a dermatitant from rhus diversiloba (poison oak). J Am Chem Soc. 1921;43(1):159-164.
5. Duke JA. Handbook of Biologically Active Phytochemicals and Their Activities. Boca Raton, FL: CRC Press Inc; 1992. http://www.ars-grin.gov/duke/. Accessed March 7, 2015.
6. Bai Y, Yoshida T. Separation of lacquer polysaccharides and interaction with poly-L-lysine. Carbohydr Polym. 2013;98(1):270-275.23987344
7. Chen H, Wang C, Ye J, Zhou H, Lu L, Yang Z. Synthesis and properties of a lacquer wax-based quarternary ammonium gemini surfactant. Molecules. 2014;19(3):3596-3606.24662075
8. He JB, Luo J, Zhang L, Yan YM, Cheng YX. Sesquiterpenoids with new carbon skeletons from the resin of Toxicodendron vernicifluum as new types of extracellular matrix inhibitors. Org Lett. 2013;15(14):3602-3605.23815600
9. Jin MJ, Kim IS, Park JS, Dong MS, Na CS, Yoo HH. Pharmacokinetic profile of eight phenolic compounds and their conjugated metabolites after oral administration of Rhus verniciflua extracts in rats. J Agric Food Chem. 2015;63(22):5410-5416.25998231
10. Song DG, Lee JY, Lee EH, et al. Inhibitory effects of polyphenols isolated from Rhus verniciflua on Aldo-keto reductase family 1 B10. BMB Rep. 2010;43(4):268-272.20423612
11. Cho N, Choi JH, Yang H, et al. Neuroprotective and anti-inflammatory effects of flavonoids isolated from Rhus verniciflua in neuronal HT22 and microglial BV2 cell lines. Food Chem Toxicol. 2012;50(6):1940-1945.22465834
12. Kim KH, Moon E, Choi SU, Pang C, Kim SY, Lee KR. Identification of cytotoxic and anti-inflammatory constituents from the bark of Toxicodendron vernicifluum (Stokes) F.A. Barkley. J Ethnopharmacol. 2015;162:231-237.25582488
13. dos Santos AL, Perazzo FF, Cardoso LG, Carvalho JC. In vivo study of the anti-inflammatory effect of Rhus toxicodendron. Homeopathy. 2007;96(2):95-101.17437936
14. Huh YH, Kim MJ, Yeo MG. Homeopathic Rhus toxicodendron treatment increased the expression of cyclooxygenase-2 in primary cultured mouse chondrocytes. Homeopathy. 2013;102(4):248-253.24050770
15. Patel DR, Ansari IA, Kachchhi YN, et al. Toxicodendron pubescens retains its anti-arthritic efficacy at 1M, 10M and CM homeopathic dilutions. Homeopathy. 2012;101(3):165-170.22818234
16. Patil CR, Gadekar AR, Patel PN, Rambhade A, Surana SJ, Gaushal MH. Dual effect of Toxicodendron pubescens on Carrageenan induced paw edema in rats. Homeopathy. 2009;98(2):88-91.19358961
17. Patil CR, Rambhade AD, Jadhav RB, et al. Modulation of arthritis in rats by Toxicodendron pubescens and its homeopathic dilutions. Homeopathy. 2011;100(3):131-137.21784329
18. Lee KJ, Yeo MG. Homeopathic Rhus toxicodendron has dual effects on the inflammatory response in the mouse preosteoblastic cell line MC3T3-e1. Homeopathy. 2016;105(1):42-47.26827996
19. Pach D, Brinkhaus B, Roll S, et al. Efficacy of injections with Disci/Rhus toxicodendron compositum for chronic low back pain–a randomized placebo-controlled trial. PLoS One. 2011;6(11):e26166.22087222
20. Duke JA, Bogenschutz-Godwin M, duCellier J, Duke P. Handbook of Medicinal Herbs. 2nd ed. Boca Raton, FL: CRC Press; 2002.
21. Myers W, Newman M, Katz B, Gottlieb AB. Ability to develop rhus allergic contact dermatitis in a patient with psoriasis receiving etanercept. J Am Acad Dermatol. 2006;55(5 suppl):S127-S128.17052536
22. McClanahan C, Asarch A, Swick BL. Black spot poison ivy. Int J Dermatol. 2014;53(6):752-753.24601999
23. Pittman MA, Lane DR. Black spot poison ivy: under the cover of darkness. J Emerg Med. 2013;44(4):e331-e332.23419214
24. Curtis G, Lewis AC. Treatment of severe poison ivy: a randomized, controlled trial of long versus short course oral prednisone. J Clin Med Res. 2014;6(6):429-434.25247016
25. Cardinali C, Francalanci S, Giomi B, Caproni M, Sertoli A, Fabbri P. Contact dermatitis from Rhus toxicodendron in a homeopathic remedy. J Am Acad Dermatol. 2004;50(1):150-151.14699391
26. Park SD, Lee SW, Chun JH, Cha SH. Clinical features of 31 patients with systemic contact dermatitis due to the ingestion of Rhus (lacquer). Br J Dermatol. 2000;142(5):937-942.10809851
27. Mersch-Sundermann V, Kassie F, Böhmer S, et al. Extract of Toxicodendron quercifolium caused genotoxicity and antigenotoxicity in bone marrow cells of CD1 mice. Food Chem Toxicol. 2004;42(10):1611-1617.15304307

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