Spotting and Avoiding Poison Oak, Poison Ivy, and Poison Sumac

Poison Oak, Ivy, Sumac

Poison Oak
Poison Oak - Three Leaves. Will Glessner ©

Though winters are harsh in parts of the country, conditions are never severe enough to quell these three woodsy nuisances. Here’s how to recognize, avoid and treat contact with Toxicodendron Diversiloba (Poison Oak), T. Radicans (Poison Ivy) and T. Vernix (Poison Sumac).

Poison Oak and Poison Ivy: The Great Mimics

Poison Ivy
Poison Ivy. Ed Reschke/Creative RF/Getty Images

Often called the "great mimics," Poison Ivy and Oak have a harmless appearance. They are difficult to distinguish from other plants, because they tend to adopt the growth pattern of the plants that surround them. If they take root among tall shrubs, they will grow as tall shrubs. If their home is a field with no tall growth nearby, they grow as a short, innocent-looking weed.

More: Photos - Is It Poison Oak or Not?

Poison Oak and Poison Ivy: Leaflets Three, Let it Be

Poison Sumac, Poison Oak, and Poison Ivy
Poison Sumac, Poison Oak, and Poison Ivy. KeithBishop/Creative RF/Getty Images

These two plants always appears nondescript, making victims wonder what exactly gave them the itchy rash a day or two later. With either species, there is one reliable truism: "Leaflets Three, Let It Be."

Poison Oak and Ivy always grow their leaves in groups of three. It doesn’t matter if the leaves look like ivy leaves, oak leaves or have a simple oval shape.

Look for the pattern of three leaflets branching from a single, independent stem.

You’ll find two leaves attached directly to the stalk, opposite each other.

The third leaf will jut from between them on a short stem, forming a distinct T pattern. In dry weather the leaves may droop, making the pattern hard to identify.

Photos of Poison Ivy

Poison Sumac

Poison Sumac
Poison Sumac. Dorling Kindersley/Creative RF/Getty Images

Poison Sumac, also known as Swamp Sumac and Poison Elder, also mimics the plants growing nearby. It’s commonly found as a multi-branched bush, but sometimes as a tree up to 25 feet tall.

T. Vernix has a completely different leaf pattern than poison ivy and poison oak. Its leaves grow in pairs of 6-12 leaves on a reddish stem with a single leaf at the end.

The leaves along the central stem are directly opposite of each other. You can tell it apart from similar-appearing plants where the leaves alternate on either side.

The leaves have smooth edges that end with a point.

Poison Oak, Ivy and Sumac: Toxic Oil Urushiol

Poison Oak
Poison Oak. Ed Reschke/Creative RF/Getty Images

The second clue to identifying the Toxicodendron Trio is that their leaves tend to have a dull gloss, especially in the Spring when the foliage is new. This sheen is the toxic oil that coats all parts of the plant: Urushiol (pronounced you-ROO-she-all). If the plant is growing in a dusty area, the sheen will be less obvious. The toxic oil is not affected.

Upon contact with any of these three plants, the oil binds to your skin. The first time this happens, your body recognizes this "attack" and prepares an immune response. You seldom have a reaction to your first contact, but your immune system certainly does.

For your second encounter, your immune system is poised to launch a severe allergic reaction. When you brush against one of these nuisances again, the Urushiol oil triggers a powerful reaction.

Like a mosquito bite, but 1,000 times worse, your immune system tries to eliminate the areas of your skin that made contact with the plant. Those areas of your skin begin to itch like mad. Scratching the itch only makes it worse, because scratching increases your immune response, and can spread the Urushiol to unaffected areas.

At this point, you have a couple weeks of misery ahead of you, as your body gradually sheds the "contaminated" skin, and the allergic reaction runs its course. Calamine Lotion and anti-itch potions can help here. They help the healing process by numbing the itch reflex, and by providing a coating to your skin that supports the healing process.

Preventing Poison Oak, Ivy, or Sumac Rash by Washing and Tecnu

Poison Oak - Leaves of Three
Poison Oak - Leaves of Three. Wendy Bumgardner ©

If you know that you rubbed against one of these plants, the FDA recommends using rubbing alcohol immediately to wipe the affected area. Alcohol will get the oil off the skin. If you carry along alcohol wipes or alcohol-based hand sanitizer, those can be used. Some towlettes such as Ivy Cleanse are marketed just for using after exposure. Then wash the affected area with plenty of soap and water. You’ll also need to wash anything you were wearing at the time. If you went to bed before you realized you had a problem, wash the sheets, your pajamas and anything else you wore afterward. Wash the dog too, if it went bounding off into strange shrubbery.

You can also treat affected areas with a urushiol neutralizer. “Tecnu” by Oak n’ Ivy is a cleanser that removes the irritating oil. They offer a treatment kit that gives immediate relief of the itching and rash, that can also be used to decontaminate laundry, pets and tools.

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