Jeff Hammer, of Moorhead, has a lot of fond childhood memories, especially those lazy summer vacations spent at his family's lake cabin in north-central Minnesota.

As one of his closest friends, I was there with him for much of the fun. We spent countless days fishing, swimming and exploring the woods, both on foot and by riding dirt bikes. It was endless adventure and constant debauchery. But many of those carefree, sun-splashed days did not end well for Hammer.

"I don't know many times I've contracted poison ivy over the years, but it's at least 50 times or more," said Hammer, an avid outdoorsman. "I've had it all over my hands, arms, legs, under my armpits, all over my torso — you name it. And use your imagination to figure out where else."

Poison ivy — the annual threat to hikers, campers, anglers and other outdoor enthusiasts — is found throughout the state and is common everywhere except in some northern-tier counties. Thousands of Minnesotans writhe in discomfort every year from poison ivy's itching, blistering, rashes and lesions.

Poison ivy, known also as Toxicodendron radicans, contains a noxious oil or sap called urushiol, which is found in the three-leafed plant's leaves and roots and can cause an allergic reaction ranging from mild to severe. Few people are immune to it, with roughly 90 percent developing an allergy after contact.

In my good friend, poison ivy found the perfect host. When we were kids, Hammer would get it on one body part and it would migrate relentlessly elsewhere, transforming from a minor rash into pus-oozing blisters and lesions that resembled third-degree burns. Why, his beloved mother Connie could have dipped her son into a pool of Calamine lotion and that wouldn't have given him any relief. (I, luckily, never once got stricken with poison ivy at the cabin. In fact, I've only had two mild cases in my life).

"It was awful," Hammer said. "I used to scratch myself bloody and raw. Calamine lotion didn't do a damn thing." Poison ivy lessons and risks

The best prevention, health professionals say, is to avoid poison ivy all together.

"The key is learning to identify it," said Kirk Hughes, education director of the Hennepin Regional Poison Center in Minneapolis. "I always say, 'Leaves of three, let them be.'"

Poison ivy is a cunning adversary, Hughes said. It can grow either as a woody shrub or as a slender vine, running along the ground or climbing shrubs, trees, fences and utility poles. "It also changes color throughout the summer and into fall," Hughes said. "It progresses from a deep green to shades of red and orange."

To reduce the odds of exposure when you venture outdoors, Hughes recommends wearing long pants, long-sleeved shirts and gloves. If you're cutting trees, gardening or burning brush, wear plastic or rubber gloves over cotton gloves.

"The oil can leech through the cotton and onto your skin," he said. "That's something you want to avoid."

He also said to wear an inhalation mask if you're burning brush, because "Inhaling smoke from burning poison ivy can cause a rash in the lining of your lungs, which can be extremely painful and make it hard to breathe."

Hughes said poison ivy's urushiol oil is extremely potent and can stay "active" for several years.

"I would venture to guess that a lot of people get poison ivy from touching something other than the plant, like petting a dog or from a chain saw that brushed up against a plant," he said. "I had one case where someone got poison ivy from cutting down a tree for Christmas. It obviously had urushiol oil on it."

If exposed, wash your clothes twice (with bleach) and clean everything that may have the noxious oil on it. Some advise wiping down clothes, shoes and tools with rubbing alcohol and water as well. "You really can't be too careful," Hughes said.

Urushiol oil can penetrate the skin very quickly. If you catch it before it turns into a reaction, wash the exposed area with cold water and dry it thoroughly with a clean towel. One remedy calls for washing with cold water first, then with milk, which helps get between the oil and the skin.

Hughes said some people who have allergic reactions get relief from over-the-counter medications, though many don't. When in doubt, contact your physician.

"When poison ivy gets on your hands and starts to spread to other parts of your body, see your doctor as soon as possible," he said. "In most cases, a steroid treatment will heal the blisters and stop the itching. If you let it go too long, you may develop an infection. You don't want to compound the problem."

Poison ivy flourishes in moist environments, and recent rainfalls and warm weather have likely provided the perfect stage for a banner growing season. My good friend Hammer recommends keeping a watchful eye out for his three-leafed adversary.

"It's been a while since I've had a brush with poison ivy," he said. "It's amazing how wise you become after you've gotten it 50 times or more."

Tori J. McCormick is a freelance writer living in Prior Lake. Contact him at torimccormick33@gmail.com.