Poison ivy: You can look, but you’d better not touch

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Poison ivy is a vigorous creeper common in suburban backyards. It can also grow as a bush. Poison ivy is a vigorous creeper common in suburban backyards. It can also grow as a bush. More than 350,000 people get poison ivy rashes annually, and scientists say the poison is getting stronger 

“Late at night while you're sleepin' poison ivy comes a-creepin' around.”

– “Poison Ivy,” written Jerry Leiber and Mike Stoller and recorded by The Coasters in 1959.

The old song had it right about poison ivy. It does creep – through flower beds, across yards, up trees and over walls; it even grows overnight. And it can sneak up on you, especially in the springtime, when you might not notice the stealthy new shoots that have sprung up in your flower beds and along the brush line.

I mention this because on Memorial Day weekend I was thinning out tiger lilies in a bed running alongside my deck when suddenly I noticed a foot-high shoot of the shiny green stuff just inches from my nose. I had never seen poison ivy in this bed before, or growing so brazenly close to my house.

The leaves and roots of what is officially termed Toxicodendron radicans and its relatives, poison oak and poison sumac, contain a clear, oily sap called urushiol that can cause an allergic reaction when it comes in contact with the skin, according to the Centers for Disease Control and Prevention.

Many of us are all too familiar with the itchy red rash poison ivy causes, and the accompanying bumps and blisters that can drive those who are allergic mad with discomfort. The rash can last for up to three weeks and is sometimes accompanied by swelling. One case I had as a child caused my face to blow up like a balloon.

While one must come in contact with the oil to get a reaction, urushiol remains active for five years, so even handling dead leaves and vines can cause a rash. In addition, oil transferred from the plant to other objects months or even years ago – such as gardening tools, clothing and even pets – can cause a reaction.

If poison ivy is eaten, the mouth and digestive tract can be damaged. Urushiol can become airborne when poison ivy is burned, and inhaling the smoke can cause a rash in the lining of the lungs, possibly resulting in respiratory difficulty.

When exposed to 50 micrograms of urushiol – an amount less than one grain of table salt – 80 to 90 percent of adults will develop a rash, the CDC says. 

According to a 2012 report by the Weed Science Society of America, recent increases in carbon dioxide during the last 50 years may have led to bigger poison ivy plants with a more virulent form of urushiol. This can be bad news for the more than 350,000 people who are stricken by poison ivy annually.

However, there are ways to prevent outbreaks and to minimize the discomfort and duration of rashes.


It is generally believed that Capt. John Smith, the 17th century explorer, wrote the first known description of poison ivy and coined its common name in 1609.

Like many plants, poison ivy appears reddish in the spring./poison-ivy.org Like many plants, poison ivy appears reddish in the spring./poison-ivy.org Poison ivy grows throughout the United States in and around woodlands, fields, wetlands, streams, wastelands, and urban environments such as parks and backyards. It often infests newly cleared woodlands around home, and is likely to be found along fence rows, stone walls, hedges and roadsides.

It is a deciduous, woody perennial that many manifest itself as a vine or a shrub. According to the Rutgers Cooperative Research and Extension service, its small red to reddish purple leaflets appear in the spring and turn a glossy green by summer; in the fall they can turn red. Each leaf consists of three egg-shaped leaflets that are 2 to 4 inches long. The edges can be either toothed or smooth.


All parts of the plant are toxic – even the roots – and anything the oil adheres to becomes toxic as well. And its poison knows no season.

Poison ivy generally turns bright green in the summer. It has inconspicuous yellow or greenish flowers with five petals and hard white, green-yellow or amber berries that are edible to birds and other animals./poison-ivy.org Poison ivy generally turns bright green in the summer. It has inconspicuous yellow or greenish flowers with five petals and hard white, green-yellow or amber berries that are edible to birds and other animals./poison-ivy.org The old saying “leaves of three, let it be” is still a good way to identify poison ivy and poison oak, but not poison sumac, which usually has clusters of seven to 13 leaves, according to the CDC. But even poison ivy and oak may sometimes have more than three leaves, and their form can vary greatly depending upon the species, the local environment and the season.

Eastern poison ivy is typically a hairy, ropelike vine with three shiny green leaves on a small stem that comes off a larger main stem. The vine’s reddish hairs are extremely toxic. It has inconspicuous yellow or greenish flowers with five petals and hard white, green-yellow or amber berries that are edible to birds and other animals.

According to Jon Sachs, the “Poison Ivy Guy" at poison-ivy.com, the noxious weed is so adaptable that it grows under very different conditions, so it shows up looking different ways. His website has photos of some of the more unusual examples of poison ivy. If you still can’t identify a plant in your yard, you can send him a photo for identification.

And if you dare, you can take a look at the website’s Skin Rash Hall of Fame.


Avoiding contact with the plant is naturally the best prevention.

Dress defensively: Wear long pants, a shirt with long sleeves, boots and gloves to minimize exposure when going near areas that may contain poison ivy.

Homeowners are advised to tour their yard, the local playground, the route their children walk to school and any other outdoor areas they frequent. If poison ivy is spotted, show it to your children and instruct them to stay away from it. 

Rutgers University’s New Jersey Agricultural Experiment Station advises that great care should be taken when cutting firewood, because many trees have poison ivy climbing on the main trunk.

Instructions for removing poison ivy can be found at njaes.rutgers.edu. Rutgers advises not to use a weed whacker on poison ivy because it can spray the leaves and the oil.   

If applied prior to outdoor activity, barrier skin creams such as lotion containing bentoquatum may offer some protection, according to the CDC.

Barrier creams, which work by making it more difficult for the urushiol to bond with skin, should be washed off and reapplied twice a day, the CDC advises.

Poison ivy's hairy vines are extremely toxic. Poison ivy's hairy vines are extremely toxic. Removal

According to Rutgers Cooperative Research and Extension, the safest and most effective method to control poison ivy is to use a brush control herbicide that minimizes your exposure to the plant. These compounds usually contain the herbicides 2,4-D, dicamba and/or triclopyrare and are sold as liquid concentrates and must be diluted with water before spraying them on foliage. When spraying, make sure to completely cover as much of the vines and leaves as possible.

After several days the leaves will turn brown and the poison ivy will begin to die. To completely control the weed, it is usually necessary to perform repeat treatments.

Caution is urged when spraying, as drift caused by wind may injure desired plants in landscape beds or vegetable gardens. Literature from Rutgers stresses that these herbicides should not be used to control poison ivy that is growing in and around trees or landscape beds.

Herbicides that contain glyphosate (most commonly sold as Roundup) will control poison ivy when applied in early summer when leaves have fully opened or in late summer-early fall prior to leaf drop, according to Rutgers, and  Roundup can also be used as a spot treatment to control poison ivy around trees and planting beds.

In situations where poison ivy is growing among desired plants, pull the ivy away from the other plants, making sure not to pull its roots out of the ground. Lay it on the ground and place several layers of newspaper under it to avoid damaging underlying plants. Dilute the Roundup with enough water so that the chemical only makes up 5 percent to 10 percent of the total solution. Spray on the foliage of the poison ivy, wetting leaves and vines to the drip point. Allow the treated plant to remain attached to the soil for five to seven so the Roundup can move down into the root system.

Roundup can also be brushed or sponged onto leaves or vines using a “glove in glove” technique. Place rubber or latex gloves on your hands and cover with cloth gloves. Dip a brush or sponge into the solution and coat the leaves of the poison ivy. 

For poison ivy that is growing up trees, cut the vines at head height and allow the upper portion to die. Treat the lower portion with Roundup and remove the growth in 10 days. Another option is to cut the vines leaving a 12-inch stump, then brush full-strength Roundup solution to the freshly cut stump.

Take proper precautions, wear protective clothing and accessories, and follow the manufacturer’s directions whenever using an herbicide. 


Urushiol binds to skin proteins and begins to penetrate the epidermis within 15 minutes of contact. If treated before it gets into the the living layer where the allergic reaction occurs, a reaction may be prevented.

The CDC recommends immediately rinsing any exposed skin with rubbing alcohol, poison plant washes or a degreasing detergent such as dishwashing soap, and lots of water. Wet compresses, calamine lotion or hydrocortisone cream can be used to reduce itching and blistering.

Contrary to popular belief, scratching the rash and fluid from oozing blisters cannot spread an outbreak or transfer it to other people, according to Topical BioMedics a manufacturer of homeopathic pain and inflammation relief products. New lesions that appear days after the initial breakout mean that less oil was deposited on that area or that the skin was less sensitive to the oil, the company said.  

Even people who have never broken out cannot assume they are immune, because the likelihood of getting a rash increases as the frequency of exposure rises.

Topical BioMedics recommends washing exposed skin with cold water. Hot water opens the pores, allowing the oil in. Then bathe the exposed area in milk, which helps to get between the oil and skin. Dry well and then apply a topical cream or ointment to help neutralize the effect of any oil left on the skin.

Scrub under the nails with a brush, as oil on the fingers can spread poison ivy to other parts of the body.

Because urushiol can stay potent for years, it is possible to get a rash from clothing or tools that got oil on them long ago. After exposure, put on gloves and wipe everything that may have come in contact with the oil – including clothing, shoes and tools – with rubbing alcohol or soap and lots of water. Then wash the clothes at least twice before wearing, if possible using bleach, and hose off garden tools well.

Herbalists and Native Americans have used a plant called jewelweed for centuries to treat and speed the healing of poison ivy, according to the folks at Topical BioMedics.  Soaps containing jewelweed and other natural ingredients such as pine tar can help decrease breakouts and soothe rashes, the company says.

While pets appear to be immune from poison ivy, it is possible for people to get a rash from oil animals have picked up on their fur. If pet contact with poison ivy is suspected, put on thick rubber gloves and bathe the pet, and then wash yourself, using cold water to keep pores closed. 

Generally redness and swelling begin 12 to 36 hours after contact, followed by blisters and itching.

See a doctor immediately in the case of severe outbreaks or other concerns.

Anyone who experiences trouble breathing or swallowing, extensive rashes or blisters or a rash that covers most of the body, a rash on the face or genitals, or swelling, especially of the eyelids, is advised to seek medical treatment immediately.

For more information see rce.rutgers.edu, cdc.gov  or poison-ivy.org.


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