Poison Ivy: The Itchuation

Poison Ivy: The Itchuation

I think just about everybody knows their own version of this story. You know, the one where the kid goes in the woods and wipes with a poison ivy leaf? This particular former classmate finished his business, and the story goes, he wiped his backside with a whole bush. The result? Total buttock conflagration. Severe pruritic backside enrashedness. Of course, being a fifth grader, this kid had to tell everyone about the rash, and the story spread faster than the big bursting bumps back there. And, from that day on, our hero was christened with an apt nickname only 10 year old peers could give: Kaboom.

And that is how poison ivy happens: Kaboom.

We are in high season here on the East Coast. We learn from studies done in 2006, poison ivy thrives in our ever warmer, more carbon rich atmosphere. Climate change produces bigger plants with more potent irritant oils. One minute you and your kids are enjoying the great outdoors, and the next minute some number of your household are blooming scads of annoying, itchy hot patches. This time of year, I see the rashes in clinic (or in my house) almost every day. The problem isn’t so much a lethal one as it is highly unpleasant. Kaboom indeed.

Everywhere and every body (almost)

Estimates are that 50-70% of people react to poison ivy, with an additional 10-15% being very sensitive (I am raising my rashy hand here). People who think they aren’t allergic may simply not have had sufficient contact with the plant. This does explain, however, why younger children—the infants and toddlers—get fewer rashes than older kids and adults. Research suggests that given enough exposure, just about everyone will break out eventually. Pass the Benadryl now, thanks.

Poison ivy and its brethren are everywhere. Poison ivy is but one member of the genus Toxicodendron, whose company includes poison oak, common west of the Rockies, and poison sumac, prevalent in swampy areas, especially in the Southeast. Poison ivy, aka Toxicodendron radicans grows in all lower 48 states, outside of desert climates, and altitudes below 4000 feet. In addition to its affinity for growing in shady areas, with moist soil, it shows a ready disposition to flourish in and around most places I reside or recreate.

Recognizing poison ivy and its cousins has been a life skill I still aim to achieve. Hopefully, you’ll do better than I do! The web is replete with excellent horticultural portraits of the fauna, in its protean formats. Poison ivy can grow as vines, in clumps with short sprigs, or as large bushes. Like poison oak, poison ivy has distinctive clusters of triple leaves that go a very pleasing technicolor in the fall. Indeed, people often quoted that old saw to me “leaves of three, let them be,” usually as I was finding a seat in a nice patch of the stuff. Poison sumac, by comparison, grows with its leaves bunched, 5-13 at a time.

Western medicine and folk remedies have thrown ideas at poison ivy for centuries, with European settlers complaining about the plant’s properties in the early 1600′s. Captain John Smith, honcho pilgrim here in my Massachusetts, is purported to have given the poison ivy it’s very name back in 1609. Hmm. I wonder idly if the T. radicans eruptions I now sport on my legs are from some great-great-great-grandplant of a vine that give that old bird himself a rash to scratch to bits. Moving on…

Urushiol: an irritant to reckon with. This oily resin is what gives poison ivy, oak and sumac their notoriety, and a brief consideration of its irritant properties tells us why. Urushiol exists on the underside of the plant, or oozes to broken sections that can rub against human skin, clothing, or animal fur. The stuff is potent: about a billionth of a gram is enough to trigger a reaction in a human. Per one colorful reference, a 1/4 ounce of urushiol could generate a rash on everyone on earth. Take home point: you must be careful to avoid or minimize contact with this material. Otherwise: rash city (more on that in a bit)!

Urushiol endures. The resin can remain on surfaces, causing mischief and irritation for up to 5 years after contact with the plant. Dead or dormant poison ivy plants in winter can still cause your skin to break out. If you don’t hate it now, at least be impressed. Take home point #2: adults and kids often recontaminate themselves by repeated contact with items (garden tools, clothing, dog) that have touched or smeared by the urushiol. To really understand our poison ivy rashes—and their mythology—it pays to look at how the body reacts to the stuff.

Poison ivy allergic dermatitis: a fortnight of fun

The extent of a poison ivy rash arises from the amount of urushiol delivered onto the skin, as well as time spent on the skin, and the thickness of the skin itself. So, on thickened skin like the sole of the foot, it’ll take longer to manifest a reaction, say, than on the thinner skin on the back of the hand. After about 20 minutes of contact with poison ivy resin, a reaction is all but certain. The human body launches a delayed hypersensitivity reaction, whereby redness and bumps can arise as soon as 8-14 hours after contact with the urushiol. But wait, that’s not all! The skin reaction can produce new bumps and water blisters for up to 2 full weeks after initial contact. Write that down, as most people are astonished to see it last so long. It goes and goes.

Take home point #3: The clear drainage coming out of burst or scratched bumps is serous fluid produced by the body, and contains no urushiol. Scratching most definitely does not spread the rash. Nor is one child’s rash contagious to another. More often, repeated contact with a slimed bit of clothing or tainted item causes additional spread of new rash to other parts of the body.

And the reaction to poison ivy appears differently by individual. A parent or health provider looking at these rashes can look for some distinctive patterns. Eruptions generally happen in exposed areas, such as the hands, arms, and lower legs. Or rashes may erupt where freshly touched urushiol resin gets smeared from one spot to another. The tendency of folks to brush by the plants creates lines of bumps or water blisters in some areas. Smudged resin, or with a large area of exposure, whole carpets of lesions emerge. Urushiol can also disperse via soot and smoke, causing potentially devastating reactions in the lungs, throat, or eyes. For this reason, never burn the any of the Toxicodendron plants. If you see a plant on fire, get clear STAT.

For the luckier kids and adults who get milder skin reactions, they may get away with some areas of redness, bumps, or a few water blisters. These rashes are famously itchy, and that unpleasant feeling can last for a few weeks until it fades and dries up. Moderate to severe cases of poison ivy rash are a bummer, and on occasion merit urgent medical attention. Kids can present in the office with swelling, as well as miserable itching and pain in the affected areas. The small bumps of minor rashes can progress to large blisters, and in some unhappy cases can become infected. In the rarer cases, kids break out in funky, bodywide rashes far outside the zones of contact with the plant’s resin. These are truly systemic reactions that may merit more heavy duty treatment.

Take home point #4: Poison ivy ‘toxin’ does not get into the bloodstream in these cases, as I’ve heard some patients and parents say. Rather, some children’s immune systems go into hypersensitivity overdrive, causing generalized rashes that are themselves an unpleasant side effect of that inflammatory response.


In the majority of homes, schools and clinics, kids present their rashes underway, and already tenderized from scratching. There are a host of benign treatments and remedies I recommend people keep in their medicine cabinets.

While I grew up painted with the fragrant, pink shellac of calamine lotion for my poison ivy, research on its effectiveness in controlling symptoms is mixed. It is inexpensive, and it has its fans. Oatmeal baths are cheap and easy and work for some, taking the edge off itching (hint: put the oats in a sock, in cool bath, to avoid pipe cloggage). Still other parents and children prefer the application of the soak, using towels moistened with Domeboro, or Burow solution, both available at commercial pharmacies.

In terms of complimentary or herbal therapies, there are claims that products containing gumweed, or 5% bovine cartilage cream may be effective in reducing poison ivy irritation. However the data on these products is limited, and they are not something I customarily recommend.

More recently, I picked up a dermatology clinical pearl that helps in the management of poison ivy itch: Cool overpowers itch. (And, conversely, hot weather, exercise, and sweat may make itching worse). Thus, I recommend the use of gels or salves (containing camphor, or menthol) in limited amounts on body parts away from the eyes and mouths of older kids. The essential oils in these products can have side effects on smaller kids (say, under 3 years) and I’d urge parents to consult with their primary care docs before deploying them.

Newer products, packaged as ‘poison ivy washes’ (eg Zenfel, or a similar pharmacy generic) may be effective in alleviating the symptoms of itching if applied in the first few days. These products don’t come cheap (30 bucks or more), but may offer another go to option if other approaches don’t work.

Oral antihistamines are another mainstay of poison ivy home care. Benadryl or Atarax are more likely to have anti-itching effectiveness than newer, non-drowsy antihistamines (eg Claritin, or Zyrtec), but have the tradeoff of making kids sleepy. Dozing at summer camp isn’t so cool, and most families find these meds help most at night, in getting kids to sleep amidst the itchy madness.

Short term doses of oral steroid therapy are reserved for the more severe cases of poison ivy reaction. Children or adults with severe pain, involvement over 20% or more of their body, or facial involvement may be candidates for these medications for a few weeks. I’d not use topical steroid creams or ointments (eg hydrocortisone) that patients may have for eczema rashes unless done in consultation with ahealth provider. If used unjudiciously, these agents can cause a rebound effect that can make rashes worse.

An ounce of prevention

The best treatment for poison ivy (and, well, most everything bad) is prevention. With kids, this is an especial challenge. It is easy to bring an adult round to the benefits of wearing long sleeve shirts or socks, and using vinyl gloves (not rubber, they’re urushiol permeable!) when working in the garden or yard. Can you get a kid to do this on an August day as they play in the woods? You can try.

If there is a known contact of a child with poison ivy, soap and water work about as well as any products marketed to remove the urushiol. To decontaminate effectively, parents should apply copious amounts of water and bath soap as soon as possible. In these cases, don’t use a wash cloth or skimp on the water, as it may merely smear the resin across the skin, and spread the rash even more. While the family dog won’t break out in a rash, contact with urushiol smeared fur could cause rashes in your children. So, as long as you are bathing kids, it might be time to wash the pooch as well.

The marketplace is replete with products that promote themselves as poison ivy barriers. Medical reviews of these products suggest their effectiveness—in light of their cost—is difficult to assess. Anecdotally, US Forest Service staff working in remote areas used heavy amounts of deodorant to their bodies to block absorption of poison ivy resin. I am not sure this is such a ‘hot’ idea. In any case, I am not (yet) a big fan of products offered for this purpose.

Lastly, technology does exist to desensitize people to the urushiol in poison ivy. However, this process is lengthy and expensive, and is more considered for people most likely to be imperiled by contact with inhalation or prolonged contact with the irritant, such as smokejumpers or forest workers. Alas, this approach is a ‘not yet’ for most kids and families.

And so go forth. Let your kids play in the yard, romp in the fields, and explore the woods. If they make contact with poison ivy, scrub ‘em. If they break out in rashes, soak ‘em and treat ‘em. If they have to make like a bear and go in the woods, warn ‘em. So they don’t go..Kaboom!

Happy summer!

photo above from this link; cartoon below by me

Poison Ivy: The Itchuation

Jack Maypole, MD has plenty of material to work from. He is director of Pediatrics at the South End Community Health Center and he is director of the Comprehensive Care Program at Boston Medical Cent ...read more


Follow Us