Toxicodendron Poisoning Clinical Presentation

Updated: Jan 03, 2017
  • Author: Steven L Stephanides, MD; Chief Editor: Asim Tarabar, MD  more...
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The history in cases of possible Toxicodendron toxicity should include questions about the following:

  • Known exposure to poison ivy, oak, or sumac
  • Outdoor activities in areas with Toxicodendron species within the previous 8 hours to 14 days
  • History of toxicodendron dermatitis
  • Contact with a pet that has been outside in an area with Toxicodendron species


The dermatitis is highly variable and depends on the sensitivity of the patient and extent of exposure.

Mild cases

In mild cases, classic lesions on exposed skin are secondary to brushing against the plant or excoriations from scratching.

Characteristics of mild classic lesions are as follows:

  • Linear
  • Erythematous, possibly edematous
  • Pruritic or mildly painful
  • May have small vesicles

Moderate-to-severe cases

Characteristics of moderate-to-severe cases are as follows:

  • Diffuse areas of erythema and edema
  • Severe pruritus and/or pain
  • Bullae (note that fluid from bullae does not contain urushiol)

Uncommonly, dermatitis from exposure to poison ivy may include black spots. This reaction is thought to result from direct contact with a high concentration of oxidized urushiol. [5]

Erythema multiforme is an atypical presentation of toxicodendron dermatitis reported after sumac ingestion.



Dermatitis from urushiol oleoresins follows exposure to members of the plant genus Toxicodendron.

Poison ivy (Toxicodendron rydbergii), poison oak (Toxicodendron diversilobum), and poison sumac (Toxicodendron vernix) are most common in North America. [6]

Urushiol can also be found in mango plants and the Japanese lacquer tree (Rhus verniciflua), although these are not Toxicodendron species; mango fruit skin can cause reactions in susceptible individuals. [7]

Exposure to unroasted cashew nut shells can cause a dermatitis often confused with toxicodendron dermatitis in susceptible individuals. Roasting inactivates the allergen.