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Treatment of Poison Ivy, Oak, and Sumac

by Dr. Abner Bagenstose

Poison ivy is the most common cause of contact dermatitis in the United States. Despite how common it is, there is a lot of confusion about how it is spread, what the rash looks like, and how best to treat it.

Let’s help clear up some of the confusion.

Recognizing Poison Ivy, Oak, Sumac

Poison ivy is the most common of a family of plants that secrete the skin irritant urushiol, the lacquer found within the sap of the plant that causes contact dermatitis. Other members of the family that are found here in Ohio include poison oak, poison sumac, spotted water hemlock, poison hemlock, cow parsnip, and wild parsnip. Contrary to popular belief, the rashes caused by these different plants produce the same rash on the skin, due to the presence of the same urushiol compounds.

Prevention is the most important goal when dealing with poison ivy. While most of us have heard the old adage, “leaves of three, leave it be,” it is important to familiarize yourself with the appearance of the various poison plants. If you are not sure, then don’t touch the plant directly. Gloves are effective, but the urushiol resin, which often turns black with air exposure, can still transfer to the skin if the gloves are reused or not washed properly. The same goes for outdoor tools. Disposable plastic grocery bags can be a useful way to handle plants when attempting removal.

Can My Dog Get Poison Ivy?

While most pets are not allergic to poison ivy, they can still accumulate the oil on their fur when exposed and later transfer it to an unsuspecting person.

Apply Poison Ivy Blocker

If you are going to be in a high risk area for exposure to poison ivy, applying an ivy blocker can be an effective way to avoid getting a rash. These products set up a protective film over the skin and prevent absorption of the urushiol compounds. These products have a limited capacity to protect, however, so it is still important after exposure to wash your body and clothes appropriately.

What to Do If You Have Touched Poison Ivy

If you do come in contact with poison ivy, you have a short window to remove the oils from your skin before they are able to induce a rash. Dishwashing soap, laundry detergent, rubbing alcohol, or specific poison ivy-branded washes can all successfully remove the resin from the skin. Make sure to remove any oil under the fingernails as this is a common hiding place. If a proper wash is not used, you can actually spread the urushiol to other parts of your skin and make the eventual rash even worse.

What Does the Poison Ivy Rash Look Like?

The rash of poison ivy typically begins as an intense itch before any skin changes are noted. Over the next few hours, an itchy, red, and blistering rash will manifest. The rash classically has a geometric pattern, especially lines where the leaves have brushed the skin or where scratching or rubbing has spread the resin already on the skin.

Sometimes, if resin is still present on the skin, black dots will be observed within the rash. The blisters will eventually fill and break open and seep clear or yellow fluid. It is a common misconception that this fluid can continue to spread the rash. Once the skin is washed of the offending oils, the rash cannot be spread farther, although many people notice the rash evolving at different times on different parts of the skin. In general, areas exposed to the most oil show the rash first, and areas with less exposure show the rash later. The blisters will eventually crust over and the rash should clear in two to three weeks on its own.

Can I Treat Poison Ivy at Home?

For at-home treatment of poison ivy, first of all, leave the blisters alone, as the overlying skin protects the raw skin underneath and can prevent infection.

Symptomatic relief of the itch of poison ivy can be aided with lukewarm baths containing colloidal oatmeal or adding a cup of baking soda to bath water. Calamine lotion has a cooling effect on the skin, can aid in itch relief and may decrease the infection risk to open skin. Antihistamines such as Benadryl may provide itch relief and can assist with sleep if the itching is keeping you awake. Hydrocortisone cream or lotion is the only treatment that addresses the underlying cause of the poison ivy rash, the allergic dermatitis present in the skin. This can be applied two times a day and other remedies alternated between applications.

When to See the Doctor for Poison Ivy

While most mild to moderate rashes due to poison ivy can be dealt with at home, it is important to remember that if you have any severe signs of allergic reaction, such as difficulty breathing or swallowing, intense facial swelling, or fever, then you should seek medical attention immediately.

If the rash is so severe that you can not get relief with over-the-counter products, then your dermatologist can help. Much stronger prescription steroids, or even systemic treatment with steroid pills or a shot can often give patients relief within a day or two.

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