Eczema & Dermatitis
Poison Ivy Dermatitis
Rhus dermatitis; urushiol allergy
Very common after outdoor exposure
No — the rash itself does not spread person-to-person
Yes — clears over 1–3 weeks
What Is It?
Poison ivy dermatitis is an itchy, blistering rash caused by an allergic reaction to urushiol, an oil found in poison ivy, oak, and sumac. The rash often appears in streaks or lines where the plant brushed the skin, usually 1–3 days after contact, and clears over one to three weeks.
Signs & Symptoms
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Intensely itchy red rash, often in streaks or lines
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Small blisters that may weep and crust
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Appears 1–3 days after contact with the plant
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Swelling, especially on the face or hands
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New patches over days as the reaction develops
Why Does It Happen?
Urushiol oil binds quickly to the skin and triggers a delayed allergic reaction. You can also pick it up from contaminated clothing, tools, or pet fur. The rash itself is not contagious — fluid from blisters does not spread it — but any oil still on the skin or objects can cause new patches. Washing off the oil quickly reduces the reaction.
Treatment Options
Wash off the oil as soon as possible, then treat the itch and inflammation. Most cases are managed at home; severe or widespread cases may need oral steroids.
WASH EARLY
Rinse skin with soap and water within hours to remove the oil.
TOPICAL CARE
Cool compresses, calamine, and topical steroids ease itch and ooze.
ORAL ANTIHISTAMINES
Help with itch and sleep during a flare.
ORAL STEROIDS
For severe, widespread, or facial reactions (a tapering course).
Tips for Managing It at Home
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Wash skin, clothing, tools, and pets that may carry the oil
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Learn to recognize and avoid poison ivy, oak, and sumac ("leaves of three")
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Don't scratch — it worsens itch and can cause infection
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Never burn these plants; the smoke can severely affect the lungs
When to Call Your Provider
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Rash on the face, eyes, mouth, or genitals
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Widespread rash or severe swelling
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Trouble breathing or swallowing after smoke exposure (emergency)
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Signs of infection: pus, increasing pain, or fever
Sources & further reading
The information in this handout is based on general dermatology guidance from the reputable organizations below. These links are provided for patients who wish to read more from trusted sources.
American Academy of Dermatology (AAD). Poison Ivy, Oak, and Sumac. https://www.aad.org/public/everyday-care/itchy-skin/poison-ivy/treat-rash
Canadian Dermatology Association (CDA). Eczema. https://dermatology.ca/public-patients/diseases-conditions/skin-conditions/eczema/
Centers for Disease Control and Prevention (CDC). Poisonous Plants. https://www.cdc.gov/niosh/plants/about/index.html
DermNet. Allergic Contact Dermatitis to Plants. https://dermnetnz.org/topics/plant-allergic-contact-dermatitis
This handout is for general education and does not replace advice from your own provider. Always follow your provider’s specific instructions.
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