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Poison ivy, oak, sumac dermatitis in Adult
See also in: External and Internal Eye
Other Resources UpToDate PubMed

Poison ivy, oak, sumac dermatitis in Adult

See also in: External and Internal Eye
Contributors: David O'Connell MD, Susan Burgin MD, Lowell A. Goldsmith MD, MPH
Other Resources UpToDate PubMed


Poison ivy, poison oak, and poison sumac are the common names for Toxicodendron dermatitis (formerly Rhus dermatitis). This is a contact dermatitis resulting from a type IV hypersensitivity reaction in sensitized individuals to the oleoresin urushiol. Urushiol is found in most parts of the plants from this genus, which is a member of the Anacardiaceae family. The Toxicodendron genus is pervasive throughout the continental United States, southern Canada, and Mexico and is mostly found below 5000 feet of altitude. It can also be found in Asia, Africa, Australia, and New Zealand. It is estimated that up to 75% of the North American population is sensitized, and the condition has no predilection based on age, sex, race / ethnicity, or skin type. Occupational and recreational exposures are prevalent.

These species show regional variations in the nature of the plant including growth pattern, leaf characteristics, and flowering.

After exposure, the rash begins to appear within 1-2 days in previously sensitized individuals; in the newly sensitized, it may be delayed 2-3 weeks. As the resin is very stable, occult contact may occur from contaminated clothing, gear, or vegetation, even after months have elapsed.


L23.7 – Allergic contact dermatitis due to plants, except food

200823002 – Allergic dermatitis due to poison ivy

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Differential Diagnosis & Pitfalls

  • Phytophotodermatitis – Similar presentation but due to plant material and ultraviolet (UV) exposure. Hogweed, citrus fruits, celery, wild parsnip, wild carrots, and oil of bergamot are among the more common causes.
  • Dermatitis due to other Anacardiaceae genera – mango, cashew, pistachio
  • Allergic contact dermatitis to some other antigen
  • Arthropod bite or sting reaction – Exaggerated vesiculobullous reactions may be associated with Chronic lymphocytic leukemia, other hematological malignancies, and Human immunodeficiency virus disease.
  • Bullous impetigo – more scattered, fragile bullae; golden crusts
  • Cellulitis or Erysipelas
  • Herpes zoster – Inquire regarding prodrome of pain or burning. Viral polymerase chain reaction (PCR) can be used to confirm.
  • Zosteriform Herpes simplex virus – Inquire regarding sensory prodrome and possible previous episode. Viral PCR can be used to confirm.
  • Porphyria cutanea tarda and Hepatoerythropoietic porphyria – bullae on sun-exposed skin
  • Solar urticaria
  • Tinea pedis – usually feet and possibly ankles; may additionally involve one hand
  • Autoimmune blistering diseases
  • Atopic dermatitis
  • Nummular dermatitis
  • Stasis dermatitis
  • Drug-induced phototoxic reaction – Severe types may blister; diuretics, antiarrhythmics, and tetracyclines are common causes.
Black dot poison ivy:
  • Melanocytic lesions, including Melanoma

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Last Reviewed:03/29/2023
Last Updated:04/06/2023
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Patient Information for Poison ivy, oak, sumac dermatitis in Adult
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Poison ivy, oak, sumac dermatitis in Adult
See also in: External and Internal Eye
A medical illustration showing key findings of Poison ivy, oak, sumac dermatitis : Erythema, Eyelids, Linear configuration, Scattered many, Tense vesicles, Arms, Legs
Clinical image of Poison ivy, oak, sumac dermatitis - imageId=113052. Click to open in gallery.  caption: 'Vesicular, erythematous plaques, some linear, and scattered vesicles on the arm.'
Vesicular, erythematous plaques, some linear, and scattered vesicles on the arm.
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