Templeton D. Climate change is making poison ivy bigger and badder. https://www.post-gazette.com/news/health/2013/07/22/Climate-change-is-making-poison-ivy-grow-bigger-and-badder/stories/201307220149 22 Jul 2013. Pittsburg Post Gazette. Accessed 22 Sep 2020. Poison ivy’s original classification, Toxicodendron radicans (T. radicans), was first established by the French botanist Joseph Pitton de Tournefort in the 17th century. Later, Carl Linnaeus, considered the “Father of Taxonomy,” classified poison ivy, poison oak, and poison sumac under the Rhus genus in 1737. 8 However, by the 18th century, 27 species of Rhus had been identified, with numerous variations, creating the need to better clarify the taxonomic designations of plants falling into the Rhus genus. Thus, the genus Toxicodendron, which means “poison tree,” was reprised for what we know today as poison ivy, poison oak, and poison sumac, with radicans and rydbergii being the most common species. Poison oak ( T. diversilobum) is more common in western United States, and poison sumac ( T. vernix) is primarily confined to marshy areas of eastearn and southeastern United States, but numerous types of Toxicodendron plants can be found in temperate climates all over the world. 7

Although the leaflets are somewhat oval, they vary greatly in shape and size. Their margins vary from perfectly smooth ( Figure 3A) to finely or coarsely toothed ( Figure 3D), to deeply and irregularly lobed ( Figure 3E). Undersides of the leaflets may be finely hairy all over, or just along the veins and veinlets, or may be virtually without hairs. These herbicides can be bought in various concentrations and under many different trade or brand names. Therefore, it is not feasible in this Factsheet to give detailed instructions for mixing and application of each kind. Detailed directions for its use are printed on the label on every container of each herbicide. Follow the manufacturer's directions. For safety's sake, read the label carefully and observe all precautions printed on it. Petrides GA. Vol. 1986. New York(New York): Houghton Mifflin; A Field Guide to Trees and Shrubs. p. 130. [ Google Scholar] Many plants have been mistaken for poison-ivy because their leaves may also consist of 3 leaflets. These can be distinguished from poison-ivy as follows.Hauser SC. New York, New York: Lyons & Burford Publishing Co.; 1996. Nature’s Revenge. [ Google Scholar] Prevalence. Prevalance of poison ivy has doubled since 1960, and its potency is rapidly increasing, making this rash a common complaint in dermatology offices. Several factors contribute to this increase in prevalence: Eating the plants can cause severe internal irritation, and inhaling particles of urushiol released by burning poison ivy, oak, or sumac can cause swelling of the respiratory passages, which can even result in death. These cases require specific and immediate medical treatment. Control Nancy Loewenstein, Extension Specialist, School of Forestry and Wildlife Sciences, Auburn University; Amber C. Dunn, former 4-H Regional Extension Agent; and Mark D. Smith, Professor, School of Forestry and Wildlife Sciences, Auburn University. While there is no entirely satisfactory treatment for TCD other than the “tincture of time,” longer-course glucocorticoid therapy, such as triamcinolone or prednisone, has been shown to be effective in relieving symptoms associated with TCD. 8 Short courses of low-dose methylprednisolone (so-called “dose paks”) are too brief and too weak to offer effective relief. Glucocorticoids should be administered using a 2- to 3-week taper starting with 60mg daily (preferably taken in the morning with food to avoid gastritis) for five days that is reduced to 40mg daily for five days and then down to 20mg daily for five days. 9 , 8 Contraindications for glucocorticoids include concurrent infection, peptic ulcer disease, poorly controlled hypertension, congestive heart failure, and diabetes. 9 Dementia can also be made worse with systemic steroids (so-called “steroid psychosis”). 9 Less serious side effects of systemic glucocorticoids include an increase in appetite, retention of fluid (edema), irritability, and insomnia. Adrenal suppression associated with prolonged systemic steroid use is rarely a problem when using a 2- to 3-week course of glucocorticoid therapy for poison ivy. 9

Caution! Even at this stage take care as poisoning may be brought about by handling the dead plants. Over-the-counter treatments for symptoms of poison ivy include external analgesics, such as benzocaine, pramoxine, and benzyl alcohol; protectants, such as zinc acetate, zinc carbonate, zinc oxide, calamine (a combination of zinc oxide, ferric oxide, mixed with phenol and calcium hydroxide), baking soda, and colloidal oatmeal; aluminum acetate (an astringent); hydrocortisone; Burow solution (an aqueous solution of aluminium triacetate); and oral diphenhydramine. 1 , 9 It is not advised to apply topical antihistamines (e.g., topical diphenhydramine) to the rash due to its potential to worsen the symptoms. 7 Unfortunately, while many of these OTC treatments might assist in drying out the weeping, oozing blisters associated with poison ivy, they often do not provide sufficient relief, especially in severe cases. 1 , 9 , 13 Lofgran T, Mahabal G. Treasure Island, FL: StatPearls Publishing; 2020. Toxicodendron toxicity. StatPearls. Last Update: April 19, 2020. https://www.ncbi.nlm.nih.gov/books/NBK557866/ Accessed 17 Sep 2020. [ Google Scholar] History. Poison ivy is neither poisonous nor a true member of the Ivy family (Hedera). Instead, it is a member of the Anacardiaceae family, which also includes pistachios, cashews, and mangoes. All members of the Anacardiaceae family contain various forms of pentadecylcatechols within their sap, which is collectively termed urushiol, an oleoresin released from the injured leaves, stems, vines, or berries of these plants. 7 For additional information on these and other herbicides, and on the selection, care and use of herbicide application equipment see Ontario Ministry of Agriculture and Food Publication 75, Guide to Weed Control. Harmful EffectsThese herbicides are usually most effective if applied anytime from when the foliage is fully developed until the plants begin to go dormant, usually from about June 15 to July 31. Some regrowth of the weed may occur after it has been treated. Therefore, examine the area periodically and the repeat treatment as often as any regrowth appears. In this manner, poison-ivy can often be eliminated from an area.

Individuals vary greatly in susceptibility to ivy poisoning and many have never suffered any ill effects. However, those in the latter category should not take for granted that they are immune for all time. Cross Reactivity Several herbicides (chemical weed-killers) have been used effectively for providing good control of poison-ivy: Figure 11. Smooth sumac leaves have eleven to thirty-one leaflets. Note that the leaflets have teeth along the edges.

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Treatment. The patient in this case report was one of approximately 500,000 cases of TCD reported each year in the United States. 17 The patient’s treatment with oral prednisolone prior to being seen by the dermatology clinic was typical but did not relieve his symptoms, nor did the calamine lotion or oral diphenhydramine. 1 , 13