While taking in the great outdoors, you may have come into contact with one of nature's troublemakers: poison ivy, poison oak or poison sumac. It's a meeting you will likely not forget. Bumping into any of these three plants can leave you with an itchy rash called contact dermatitis.

The Problem: Urushiol

The immune response leads to inflammation, redness and the development of itchy blisters. In some cases, swelling, oozing and even infection can occur. The severity of the reaction varies, depending on the amount of exposure to urushiol and your sensitivity.

Identifying the Three P's: Poison Ivy, Poison Oak and Poison Sumac

Your first line of defense is knowing what each of these plants looks like — and then to politely avoid them.

Poison Ivy

• Grows as a vine or shrub
• Leaves are pointed, clustered in threes and are sometimes glossy
• Stem has a reddish tint and can be hairy
• Leaves turn colors with the seasons: reddish in spring, green in summer, and yellow, orange or red in fall
• Can have greenish-white flowers and white berries

Poison Oak

• Grows as a vine or shrub
• Green leaves with a scalloped appearance
• Leaves are clustered typically in groups of three, but can be up to seven
• Can have whiteish-yellow berries

Poison Sumac

• Grows as a shrub or tree
• Each long leaf has clusters of seven to 13 smooth-edged leaflets
• Leaves turn colors with the seasons: orange in spring, dark green in summer, and yellow, orange or red in fall 
• Stem is reddish
• Can have yellowish-green flowers and small white fruits that hang in loose clusters

Tame That Itch: Treatment Options

"If you suspect you've come into contact with poison ivy, poison oak or poison sumac, wash the exposed area thoroughly and immediately with soap and warm water," says Alin K. Abraham, MD, an internal medicine and pediatrics physician at Northwestern Medicine. "This will help remove some of the urushiol oil before it penetrates your skin."

If you suspect your pet has come in contact with any of these plants, wash your pet as well. "It's rare that a pet will react to urushiol because of their protective coat, but the coat or fur can transfer the oil to your skin on contact," she says. You should also wash your clothing, shoes and anything you touched after your brush with urushiol, like gardening tools and gloves, your pet's leash, a golf club or door knobs.

To ease the itch and promote healing, over-the-counter remedies can help:

• Calamine lotion
• Hydrocortisone cream
• Oral antihistamines

Your rash should disappear after about two to three weeks. In the meantime, refrain from scratching to avoid infection.

When to Seek Medical Help

In more serious cases where a rash is widespread, involves your face or genitals, or involves a high fever over 100 degrees F, you should seek medical attention. Your physician may prescribe stronger topical or oral steroids.

To avoid a rash entirely, especially if you know you'll be working around poison ivy, poison oak or poison sumac, you can apply an over-the-counter barrier product in addition to wearing protective clothing and shoes. Available as creams, lotions, sprays, gels and towelettes, barrier products can help prevent urushiol oil from contacting your skin. "If you have a history of severe allergy, avoidance is key along with rinsing immediately after any suspected contact," says Dr. Abraham.

Learn more about contact dermatitis.