Skip to content

Poison ivy spreading, more toxic, warns Back Roads Bill

Itching to know what it looks like, where you might find it and what to do if you have found it? This week Bill scratches that itch

You’ve spent a glorious day on the back roads, hiking, picking berries or picnicking well, whatever you did, you’re now itchy, splotchy and covered in little red bumps.

No one seems to know why poison ivy causes an allergic reaction in human beings but it is becoming more toxic and spreading northward.

You may have even noticed this spring that it appears to be thriving more so than in the past. The leaves are looking more vibrant and there is more of it. Your poison ivy rash may even feel itchier.

It’s not your imagination it is the allergy-inducing sap called urushiol (pronounced like this) and it's stronger than it was before carbon dioxide levels started to climb significantly in recent years. Urushiol is an oily mixture of organic compounds with allergenic properties found in plants of the family Anacardiaceae, including cashews, mangoes, pistachios and poison ivy.

Research shows that the main culprit of its spread is climate change because of increased concentrations of carbon dioxide in the atmosphere — supercharging the poison ivy.

Susan Pell Ph.D. is the Acting Executive Director United States Botanic Garden in Washington. With 200 years of history, the garden is a living plant museum that informs visitors about the importance, and often irreplaceable value, of plants to the well-being of humans and to earth's fragile ecosystems. Susan specifically researched this plant and is a leading expert.

"Is poison ivy becoming more toxic and spreading northward?” I asked her.

“Yes. Scientists from Duke University published a study that looked at the impacts of elevated carbon dioxide levels on the growth and virulence of Toxicodendron radicans, poison ivy. Not unexpectedly, they found that increased carbon dioxide levels caused increases in the growth and biomass of poison ivy. What was unexpected is that they also found that poison ivy growing under these conditions also produced more virulent urushiol," she said.

"Their study did not look at northern range expansion of poison ivy but numerous studies have documented the impacts of climate change on plant distribution, and I would expect poison ivy to be similarly impacted."

Identification and Prevention

With some determined sleuthing, I located two dermatologists after making my way through the maze of institutional communication protocols. It is worth it to know more.

Through Ontario-born Caitlin Jenney, senior director of Communications, Children's Hospital Colorado, (founded in 1908 and judged to be one of the leading children's hospitals in the U.S.) I found Lori Prok, MD Pediatric Dermatologist and Dermatopathologist.

“I became interested in contact dermatitis in general while I was a first-year dermatology resident, when Dr. Jack Ailing, an expert in contact dermatitis, taught us some great pearls for recognizing contact dermatitis from a variety of common and uncommon allergens," she says in her biography. "Identifying contact dermatitis and its causes is always an intriguing and satisfying problem to solve, and so helpful for patients. It's a common patient complaint and something I see frequently in my pediatric dermatology practice.”

She said, when the skin comes in direct contact with an irritating or allergy-causing substance, contact dermatitis can develop. Exposure to poison ivy, poison oak, and poison sumac cause more cases of allergic contact dermatitis than all other plant families combined.

Generally, poison ivy has three green or reddish-green leaflets per leaf with flowering branches on a single stem.

“Poison ivy plants produce a green or off-white fruit in autumn, and in some cases, black dots form on the plants' leaves. It is not always possible to identify the plant by the leaves alone since the appearance can vary depending upon the season, growth cycle, region, and climate," Prok explains.

“People of all ethnicities and skin types are at risk for developing poison ivy dermatitis. The severity of the reaction decreases with age, especially in people who have had mild reactions in the past. The best way to prevent poison ivy dermatitis is to identify and avoid the plants that cause it. These plants can irritate the skin year-round, even during the winter months, and they can still cause a reaction after dying.”

Her recommendation is to wear protective clothing, including long sleeves and pants, when working in areas where toxic plants may be found.

“Keep in mind that the resin and oils from the toxic plants can be carried on clothing, pets, and under fingernails. Wear heavy-duty vinyl gloves when doing yard work or gardening. The oils from toxic plants can seep through latex or rubber gloves.”

After coming in contact with poison ivy, remove any contaminated clothing, she advises.

“As soon as possible (minutes count, but you can try up to two hours later), wash under very warm or hot running water using dishwashing liquid on a damp washcloth. Wash your entire body three times, while always wiping in one direction and not back and forth. This seems to reduce irritation and help remove the oils. If you do not have rapid access to dishwashing liquid, try to use plain water and wipe your skin in the same fashion; you will at least get rid of some of the resin. Comparison of dishwashing liquid with more expensive products made for removing poison ivy oils did not show a difference in effectiveness.”

“Creams and ointments that create a barrier between the skin and the urushiol oil may be somewhat effective for people who are frequently exposed to poison ivy.”

Prok also says people should avoid burning poisonous vegetation, which can disperse the plant particles in the smoke, irritate the skin, and cause poison ivy dermatitis.


Dr. Pamela Ng of the Cleveland Clinic through Ann Bakuniene-Milanowski, Editorial Director, at the Cleveland Clinic. It is the world's first integrated international health system, and has more than 200 locations across the globe — including those in North America, the United Kingdom and Abu Dhabi it has pioneered many medical breakthroughs; U.S. News & World Report consistently names Cleveland Clinic as one of the nation's best hospitals in its annual America's Best Hospitals survey.

"When the plant is broken, the resin leaks out, you’ll get this rash everywhere the resin touches — and then, if you get it on your hands and touch your face or other parts of your body, you’ll spread it,” she explains in an article entitled Health Essentials.

Poison ivy rash (along with the rash from poison oak and poison sumac) brings on bumps, blotches and, typically, a linear streak of swelling and blisters. “It can even be weeping and crusting,” Dr. Ng says, “and it’s intensely itchy.”

But the rash may not appear right away.

“If you’ve been exposed to urushiol in the past and are re-exposed again, your rash will appear in four to 96 hours (though 24 to 48 hours is most common). But if it’s your first time being exposed to the plant, it can take up to two weeks for a rash to appear," Ng explains.

“Your immune system has to develop an allergic reaction first,” Ng says. “So if it’s the first time your body has ever seen it, it’s going to take a while for the rash to appear.”

Poison ivy rash is easily spread — on your body and even from pets to humans.

“If you touch a poison ivy plant with your hands, for example, and then touch your face or body, you’ll see a rash at both the original point of contact and the places you’ve touched," Ng says.

And you don’t necessarily have to make contact with the plant itself in order to make contact with the resin.

“People can break out after contact with the resin on their gardening tools, their clothing, or their dogs.”

If you know you’ve come into contact with poison ivy, take a shower to wash off the resin.

“You won’t be able to get it all — after 10 minutes of washing your skin, only about 50 per cent of the urushiol resin comes off — but you can lessen its impact," she says.

Unfortunately, the best natural remedy for poison ivy is time. “Poison ivy just has to run its own course,” Dr. Ng says. “But if your rash has already developed, there are steps you can take to bring some relief in the meantime. Use cold compresses: Three to four times a day, cover the affected area with a damp towel for relief — but don’t get it too wet. You want your skin to feel cool, but it shouldn’t turn soft, moist and whitish (called “maceration”).

Oatmeal baths or soaks are good home remedies for poison ivy itch, as they can relieve skin irritation. “They’re very soothing and can help dry up the rash,” Dr. Ng says. Take an oral antihistamine: Over-the-counter allergy medications such as Benadryl can counter your allergic reaction to urushiol. Calamine lotion and lotions containing menthol can help with itching, too.

“Avoid other topical treatments: Stay away from benzocaine and topical antihistamines, which don’t offer any additional benefit. Plus, using them can induce sensitization to some of the components of these creams, which increases your risk of developing an allergic reaction to them in the future. Protect your skin: Keep your rash clean to prevent infection, and if it’s blistered or weeping, wear long sleeves or a light bandage.”

“Try your hardest not to pick or scratch,” Dr. Ng urges, “because once the skin is open, you’re susceptible to infection.” Clip your nails short and wear long sleeves to lessen the likelihood of scratching. If you’re wondering how long it takes for poison ivy to go away, she said you’ll have to be patient. The bumps and blisters can last 14 to 21 days.

A Sufferer

Mike Walker is a Facebook follower and when I posted an earlier photo he volunteered the following.

“My first experience with poison ivy was as an eight-year-old lucky enough to grow up near Gravenhurst at my family cottage," he said. "We had played around a new beaver pond all day and by nightfall, I was an itchy kid.

"By morning I had scratched in my sleep and moved it from my legs to everywhere. I must have had a very bad reaction as our doctor gave Mom a prescription for a green gelatinous salve which I marinated in for one week."

Years later he suffered a second infection.

“Having learned that colour is important to identify plants my next dose of the ivy came in the Ottawa valley when we were bush camped on Crown land down a logging road.

"We came back to our campsite after fishing and realized we had forgotten to grab more firewood," he said. "I had done a survey of the woods around our camp and found no oily deep green three-leaved beasties before I set up my tent upon arrival.

"I grabbed my chainsaw out of the truck and set about making a pile of firewood from a dead standing tree and its bits on the ground. Well, poison ivy as a vine had wrapped itself around the fallen limbs and my chain showered me with its oily goodness.

"By the time I left the next day, I was exhausted and itchy. I had to stop and rest several times on the five-hour drive home as I got worse.

"I remembered my Grandmother saying 'The boy needs an oatmeal bath' to my mom before I went to the doctor as a boy so I stopped by the pharmacy on the way home.

"After several days of soaking in a liquid porridge, a small jar of steroidal cream was the next prescription and I came back to life again."

Three times were not lucky for Walker. Years later, he was exposed to poison ivy again.

“I eventually cobbled together a fishing boat and we thought we would have better luck camping on an Island in the Madawaska River. The fishing was great and we thought we had found heaven.

"I had checked a few acres around camp and found no dark green oily leaved beasties or ropes of autumn-coloured glistening oily leaves of death.

"Around day four I was not taking the heat well and by day five I seemed to be being attacked by a flock of biting flies. A steady breeze flowed onshore by our camping spot and we sat in the shade for a few more days in the natural AC under the shade of the pines as I weakened.

"Eventually, the week had expired and a dazed and itchy me lurched homeward. I told the Emergency Room doctor about the biting flies and she wrote a script for that which did nothing.

"The following day, sicker than death, I went to a walk-in clinic where the attending physician believed I had a severe bout of poison ivy but after what I had been thru he asked if I would mind going to see a specialist.

"The specialist immediately diagnosed an extreme case of poison ivy. He asked me if I planned to return there and I offered 'Of course! The camping is free, the fishing is great and the land is beautiful!' 

"He related that he thought I was mad enough and wrote me a prescription for a steroidal cream”

From my similar extreme experiences and ingesting steroid pills for 21 days there seems to be a preponderance of being easily re-infected.


And for a natural remedy, Facebook friend Charlene Schrock offered these tips, “Jewelweed, also known as spotted touch me not, is an antidote to poison ivy. It often times grows close to poison ivy.

“Sometimes you can find soap sold at stores which are made with jewelweed to pack for camping trips.”

She reminds us colloidal oatmeal provides relief” but is not the same as regular oatmeal.” It is made by grinding oat grain, or Avena sativa, into a fine powder. It’s considered an emollient — a substance that softens or soothes the skin — because it packs fats, proteins, vitamins, minerals, and other nutrients shown to benefit the skin.

Above all of this there is the old saying "Leaves of three, let them be” remember that on the back roads and know how to ID this one.


Bill Steer

About the Author: Bill Steer

Back Roads Bill Steer is an avid outdoorsman and is founder of the Canadian Ecology Centre
Read more