Poison ivy is caused by a reaction to an oily resin (urushiol) found in the leaves, stems and roots of poison ivy (and poison oak and sumac). The plant leaves can be light green to red, and occur in leaf triplets that grow on their own stem. The plant may have green or white berries, and grows as either a bush or a vine.
Though exposure is most common during the spring/summer months, the leaves and vines can be hidden in fall leaf piles. Burning the plant can cause dangerous fumes that may cause damage to airways and lungs. Contact with the plant most typically causes the rash, but oil carried on clothing, gardening tools or a pet’s fur can also be the culprit. About 70-85% of people are sensitive to the resin.
The rash typically looks like lines or patches of reddened, raised skin that then blisters, and is quite itchy. The reaction can take several hours to days to appear after coming in contact with the resin (which is absorbed by the skin, causing a hypersensitivity reaction.) The rash cannot be spread by itching or touching, but it can appear in stages depending on which area of skin was most exposed to the resin. The rash is not contagious (you must touch the resin to develop the reaction.) Most rashes last between 1-3 weeks.
After known exposure to poison ivy, wash with soap and water ASAP to remove the resin from the skin. Once the rash is present, the resin has already been absorbed and simple washing will not help. Zanfel and Technu are topical solutions that can help remove bound urushiol from the skin, and can be used on a daily basis after the rash has appeared to reduce progression and severity (usually 1-2 applications are enough to halt progression and ease itch.)
Over the counter preparations such as calamine lotion and hydrocortisone 1% (Cortaid cream) are effective for mild cases of poison ivy. Apply 3-4 times a day. Cold compresses, ice packs, colloidal oatmeal creams/baths can also help itch, and Benadryl can reduce nighttime symptoms.
If the rash is on the face or genitals, or is extensive or spreading rapidly, you should make an appointment to be seen. Oral steroid treatment may be necessary, but we must confirm that the rash is indeed poison ivy prior to prescribing.