This story has been updated to correct errors.

Stretching the length of Lizbeth Mang's garden and nearing a foot deep, English ivy threatened to engulf every plant in sight.

Every so often she trimmed any stray ivy that crept up her moai-inspired garden statue with no issue. This year, however, she had tolerated enough of the invasive plant and wanted to make room for five small arborvitae trees.

It took two days of cutting, digging and hauling armfuls of ivy out of the yard to clear half of it.

While pulling it out, she unwittingly allowed the ivy to touch her exposed skin. By the end of the second day, she had developed an unbearable rash that overtook her arms, neck and face before spreading to most of her body.

"It was so incredibly itchy and uncomfortable," said Mang, a Wooster resident. "I know all about poison ivy, but I didn't know English ivy was also poisonous."

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Nearly 85% of the population is allergic and 15% is extremely allergic to poison ivy. The plant affects some 50 million Americans every year at varying degrees of severity, according to the American Skin Association.

While English ivy has a long history of health uses, 1 in 10,000 people are allergic to English ivy and can experience severe allergic reactions by just touching the plant, according to Healthline. 

Mang decided to write down her encounter with English ivy to warn others about a potential allergic reaction.

"Everyone I talked to didn't know that English ivy could do this," she said.

Nearly three weeks after the incident, Mang is still healing with noticeable red marks on her arms that itch.

"It wants me to know that it's still here," she said, looking at her red forearm.

The most commonly known poisonous plants are poison ivy, poison sumac and poison oak. English ivy is often overlooked and is used in landscaping as ground cover, but it can be just as dangerous for those who are allergic.

Poison ivy secretes an oil called urushiol that causes irritation, itchiness, rash and blisters, said Cathy Herms, a researcher at The Ohio State University's Department of Agriculture and Horticulture. 

While English ivy is known for its three to five-lobed points on a leaf and is usually a dull green color, poison ivy has three leaves and may look waxy. 

"The saying 'leaves of three let it be' is a cliché, but I'd say it is really true," said Herms, an expert on various weeds and native plants like poison ivy. 

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The two ivies have a knack for climbing. To do this they both use an almost web-like aerial root network on their stems to attach themselves to surfaces like trees and buildings.

"These roots make the vine very hairy, so if you have a grapevine, it doesn't have aerial roots all over the plant," Herms said. On poison ivy, the webby hair-like roots cover nearly the entire plant.

Herms also warns that the change of seasons doesn't make poison ivy any less dangerous.

While English ivy retains its leaves all year, poison ivy turns red in the fall and loses all its leaves in the winter, leaving a stem and root system that secretes the infectious oil.

When Mang discovered she had an allergic reaction, she used vinegar to treat the rash and took oatmeal and baking soda baths.

She even threw out her clothes and bedsheets she slept on just in case.

English ivy does not secrete urushiol oil. Instead, it consists of two allergens that can cause skin irritation even in those who are not allergic after prolonged exposure, according to a study written in 2009.

For English ivy exposure, the study recommends oral and topical steroids. 

If exposed to poison ivy's urushiol oil, Herms said to wash the exposed site as soon as possible with soap.

The quicker the oils are washed off, the less likely a reaction will occur, but if it takes a few hours or until the next day to be cleaned, a rash or blister might appear. 

"Depending on how sensitive you are it might become hypersensitive or a rash or blister might develop, but that's normal," Herms said. "It's the body's immune system response."

Once the oils are removed, there is no threat of spreading it, she said, even if a blister pops.

For more serious cases, Herms recommends seeking medical attention.

The oil secreted by poison ivy spreads very easily and is so persistent that it can stay potent on a surface for years, so the proper precautions need to be taken.

Long-sleeved clothes and gloves usually do the trick, but extra attention should be paid to where the arm sleeve and glove meet at the wrist. 

"We often see people who say they were geared up but had a reaction around the wrist," Herms said. 

She noted that poison ivy treatment creams and preventives, similar to sunblock, are good items to have on hand.

If exposure is suspected, wash the afflicted area with soap to remove the oils. 

Herms said a quick spin in the washing machine should be enough to rid clothes of the oil.

If dogs or cats are exposed to poison ivy, Herms recommends giving them a bath with gloves.

"If your dog is running through poison ivy and then you go pet your dog, you have it on you," she said. "If you're walking through it, and it's on your pant legs, on your shoes, and then you go and you take your shoes off, then you've got it on your hands."

The oil can even travel in the air if burned, getting into people's lungs and is sometimes found in mulches. 

Poison ivy is indigenous to North America and feeds much of the wildlife in the Eastern U.S., but this doesn't mean it shouldn't be removed from yards.

Herms warns against manually removing poison ivy by hand, even with gloves. Instead, she recommended using any herbicide to kill the plant. 

"If it is climbing up a tree, you can cut a knot out of the stem so the disconnected portion dies," she said. "Then you can spray the remaining parts on the ground."

But the best way to stop either ivy from taking root is by killing the seedling with a herbicide.

This article was updated to reflect that urushiol oil is in poison ivy, not English ivy. English ivy can cause dermatitis in those who are allergic or after prolonged exposure. The two plants are not related. 

Reach Bryce by email at bbuyakie@gannett.com