Causes

The rash that occurs after contact with poison ivy, oak, or sumac is caused by urushiol, an almost invisible, clear-to-slightly-yellow oil that comes from any cut or crushed part of the leaves, stem, or vine crawling on the ground. The oil can be carried for up to 3 days on the paws or fur of cats and dogs. It can be carried on shoes, clothing, or on garden tools for weeks or months.

Symptoms

When urushiol touches the skin, it penetrates within minutes. In 12 to 48 hours a red, itchy rash and tiny, weeping blisters may appear.

Treatment

Usually exposure to these poisonous plants can be treated at home with self-care. If the rash covers a large area or involves your face or eyes, see your doctor. Your doctor may treat a very bad reaction with cortisone.

Prevention

Your best defense against these poisonous plants is to learn to identify them by sight, and watch what you’re handling when gardening, hiking, or cleaning up around the yard. Try not to break the plant, because the oil is in all parts of the plant.

Poison ivy usually grows east of the Rocky Mountains as a vine or shrub. Its leaves are in clusters of three, and it has yellowish-white berries. It grows easily and is widespread both inside and outside city limits.

Poison oak grows west of the Rockies as a shrub, small tree, or, less often, a vine. It has greenish-white berries and has leaves in clusters of three, similar to those of poison ivy.

Poison sumac is found in swampy, boggy areas in the South and northern wetlands. It’s a tall shrub with 7 to 13 pointed, small leaves per branch and cream-colored berries.

If you have to work near infested areas, wear long pants, long sleeves, rubber gloves, and boots. Over-the-counter barrier products, such as Ivy Block and Stokoguard, can also offer protection.

Self-Care

• Wash suspected areas of contact with soap and water as quickly as you can. If necessary, use water from a nearby stream, lake, or garden hose. Washing skin within 60 minutes of exposure will lessen your reaction.
• If water isn’t available, wipe affected areas with rubbing alcohol (though this may cause urushiol to spread).
• Use water to rinse off pets, clothes, shoes, and camping or gardening gear if you or your pets have been in infested areas.
• Tecnu is a solvent specially designed to remove urushiol oil from the skin. It needs to be flushed off with water to avoid spreading the urushiol to other parts of your skin.
• Cool compresses are the best treatment for a rash. Calamine lotion or Cortaid may also be used to relieve initial itching and help dry the rash.
• Over-the-counter antihistamine pills (such as Bendadryl) may relieve itching. However, these medications may cause drowsiness.
• A soak in lukewarm water mixed with an oatmeal bath product or baking powder may soothe irritated skin and dry oozing blisters over large areas.