You have to give poison ivy credit for its resilience. It thrives almost everywhere in the United States, and each year more than 10 million Americans will have close, itchy contact with it, according to the American Academy of Dermatology. And if you come in contact with the oil released by poison ivy, you may suffer blisters, redness, swelling, and itching. What's worse: That oil, called urushiol, is odorless, colorless, and can be passed along on clothing, pet fur, yard tools, and sports equipment. Here's how to prevent exposure, clean up if you do come in contact with the dreaded plant, and relieve its most troublesome symptoms.

"Prevention is key," says Dr. Linda Stein Gold, director of clinical research in the department of dermatology at Henry Ford Hospital in Detroit. Wearing long clothing helps because it keeps the plant away from your skin, but be aware that the oil can stick to clothes and contaminate your skin as you undress. So use a lotion containing bentoquatam, which prevents the oil from binding to skin. Apply to exposed skin at least 15 minutes before stepping outside to prevent or reduce the severity of poison ivy rash. It's not recommended for children under age 6.

"You have 15 to 30 minutes before the oil binds to the skin and begins to penetrate, which may lead to a reaction," says Dr. Joseph Fowler Jr., a dermatologist in Louisville, Kentucky. Soap and water work very well if you wash immediately after exposure, but if you don't clean up within that short window, you'll have a more difficult time avoiding the rash. Make it a practice to wash all exposed skin thoroughly after yardwork. Best yet, take a quick, soapy shower.