Poison ivy (Eastern U.S.) or poison oak (Western U.S.) is a delayed allergic reaction. Brushing the plant on the skin results in blisters and slightly elevated lesions 1-2 days after exposure, accompanying a severe itch.
Poison ivy (Eastern U.S.) or poison oak (Western U.S.) is a delayed allergic reaction. Brushing the plant on the skin results in blisters and slightly elevated lesions 1-2 days after exposure, accompanying a severe itch.
Poison ivy, or poison oak, typically has a linear pattern.
Poison ivy, or poison oak, typically has a linear pattern.
This image displays the line-like configuration of the inflamed skin lesions typical of poison ivy.
This image displays the line-like configuration of the inflamed skin lesions typical of poison ivy.
This image displays poison ivy in linear lesions, due to the patient either rubbing the allergen across the skin or brushing up against the poison ivy plant.
This image displays poison ivy in linear lesions, due to the patient either rubbing the allergen across the skin or brushing up against the poison ivy plant.
The irregular bumps of early poison ivy dermatitis may resemble acne when on the face.
The irregular bumps of early poison ivy dermatitis may resemble acne when on the face.
This image displays the poison ivy allergen on the face.
This image displays the poison ivy allergen on the face.
This image displays a rash with a linear distribution typical of poison ivy.
This image displays a rash with a linear distribution typical of poison ivy.
Poison ivy often causes facial swelling and
Poison ivy often causes facial swelling and "weepy" skin lesions.
This image displays fluid-filled blisters typical of the intense allergic reaction of poison ivy dermatitis.
This image displays fluid-filled blisters typical of the intense allergic reaction of poison ivy dermatitis.
This image displays poison ivy, which is identifiable by the grouping of three leaves. Also note: Berries carry the allergen as well.
This image displays poison ivy, which is identifiable by the grouping of three leaves. Also note: Berries carry the allergen as well.
This image displays the poison oak plant, which, like poison ivy, has 3 leaves. Unlike poison ivy, however, the poison oak plant typically looks more like a shrub and has leaves that resemble an oak tree's leaves.
This image displays the poison oak plant, which, like poison ivy, has 3 leaves. Unlike poison ivy, however, the poison oak plant typically looks more like a shrub and has leaves that resemble an oak tree's leaves.
Poison sumac has between 7 and 13 leaves on each branch of the plant. Poison sumac can be differentiated from nonpoisonous types of sumac by the location of the fruit on the plant, with the fruit of the poisonous plant growing between the leaf and the branch, opposed to the ends of the branches.
Poison sumac has between 7 and 13 leaves on each branch of the plant. Poison sumac can be differentiated from nonpoisonous types of sumac by the location of the fruit on the plant, with the fruit of the poisonous plant growing between the leaf and the branch, opposed to the ends of the branches.

Images of Poison Ivy, Oak, and Sumac (12)

Poison ivy (Eastern U.S.) or poison oak (Western U.S.) is a delayed allergic reaction. Brushing the plant on the skin results in blisters and slightly elevated lesions 1-2 days after exposure, accompanying a severe itch.
Poison ivy, or poison oak, typically has a linear pattern.
This image displays the line-like configuration of the inflamed skin lesions typical of poison ivy.
This image displays poison ivy in linear lesions, due to the patient either rubbing the allergen across the skin or brushing up against the poison ivy plant.
The irregular bumps of early poison ivy dermatitis may resemble acne when on the face.
This image displays the poison ivy allergen on the face.
This image displays a rash with a linear distribution typical of poison ivy.
Poison ivy often causes facial swelling and
This image displays fluid-filled blisters typical of the intense allergic reaction of poison ivy dermatitis.
This image displays poison ivy, which is identifiable by the grouping of three leaves. Also note: Berries carry the allergen as well.
This image displays the poison oak plant, which, like poison ivy, has 3 leaves. Unlike poison ivy, however, the poison oak plant typically looks more like a shrub and has leaves that resemble an oak tree's leaves.
Poison sumac has between 7 and 13 leaves on each branch of the plant. Poison sumac can be differentiated from nonpoisonous types of sumac by the location of the fruit on the plant, with the fruit of the poisonous plant growing between the leaf and the branch, opposed to the ends of the branches.

Poison Ivy, Oak, and Sumac

Poison ivy, oak, and sumac plants contain an oil called urushiol. Leaves, stems, roots, and berries of all of these plants cause the same type of skin rash. Upon contact with the skin, the oil can trigger an allergic reaction that can appear within hours of the exposure up to several days later. It is important to note that an affected person may experience an allergic reaction by coming into contact with the oil either directly (ie, by touching the plant) or indirectly (eg, by touching gardening tools, pet’s fur).

The itching is usually intense and the affected person can develop itchy bumps (papules) or blisters (vesicles). While a poison ivy, oak, or sumac rash is not initially infected, secondary bacterial infection can result from scratching the bumps or blisters. The lesions are not spread by scratching, however; the lesions with the most antigen appear first and then, as the immune response increases, lesions with less antigen begin to erupt.

Who's At Risk?

Both males and females of all ages are equally affected by poison ivy, oak, and sumac.

Signs & Symptoms

  • Poison ivy, poison oak, and poison sumac can occur anywhere on the body where the exposure to the plants has occurred.
  • Linear red and brown-red raised areas and blisters are noted. Crusted lesions may be seen.
  • A “black dot variant” has been described (the oil from the plant leaves a black dot on the skin).
  • Extreme facial swelling (edema) may be seen if there is significant exposure to the face.

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Self-Care Guidelines

  • It is important to use soap and water to wash all potentially exposed areas since the oil of the poison ivy, poison oak, and poison sumac plants adhere to the skin.
  • Once the oil has been washed off, there is no risk of spreading poison ivy, poison oak, or poison sumac to other parts of the body.
  • Be sure to wash any garments potentially exposed to the oil as well.
  • Soothing oatmeal baths (such as Aveeno® Skin Relief Bath Treatment) and calamine lotion may be helpful in relieving symptoms.
  • Wear protective clothing (eg, pants and long-sleeved shirts) and barrier cream (Ivy Block™) applied 15 minutes before potential exposure to avoid future reactions.
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Treatments

Your physician may prescribe:

  • In severe cases involving large body areas, a 14 to 20-day course of oral steroids (prednisone).
  • In cases with more limited skin involvement, medium- to high-potency topical steroids may be used to treat the trunk and extremities, while low-potency topical steroids may be prescribed to treat the face and skin fold areas.
  • Oral antihistamines may be prescribed for itching.
  • Topical or oral antibiotics may be needed if an infection is suspected.

Visit Urgency

Seek medical evaluation for a rash that does not respond to self-care measures or appears to be flaring or worsening.

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References

Bolognia, Jean L., ed. Dermatology, pp.227-229. New York: Mosby, 2003.

Freedberg, Irwin M., ed. Fitzpatrick’s Dermatology in General Medicine. 6th ed, pp.1167-1168. New York: McGraw-Hill, 2003.