Poison Ivy Oak and Sumac

Poison Ivy, Poison Oak and Poison Sumac

I'm about to confess to one of the reasons that I went into botany. One time, long ago when I was a kid, I was playing in a vacant lot on Mordecai Drive in Raleigh, North Carolina, and unknowingly used poison ivy as toilet paper. I got a bad rash in a bad spot, and it tormented me for more than a week. To avoid a repeat of that experience, I figured it would serve me well to learn how to recognize poisonous plants. Well, one thing led to another, and I wound up as a botanist.

Although I never repeated that particular mistake, I still have a fairly close, although mostly rash-free, relationship with poison ivy. A big patch of it has practically surrounded the mailbox at my Herbal Vineyard. If I don't thin it periodically, it becomes a problem for my neighbor, whose mailbox is next to mine and who is extremely sensitive to the plant.

So when the poison ivy grows into a sizable clump, I go out and grab a bunch of jewelweed, a succulent, orange-flowered annual that grows in moist meadows on my land. I crush a ball of it in my hands and rub myself down with its juice. Then I spend 15 or 20 minutes pulling up the poison ivy, rubbing myself with jewelweed juice periodically. The result? My neighbor is happy, and I never get a poison ivy rash.

Most but not all Americans are sensitive to the irritating oil, urushiol, that's found in plants like poison ivy, poison oak and poison sumac. Those who are sensitive develop a nasty, persistent, blistering rash after contact. It's not clear why some people are relatively or even completely immune to these oils. While it's estimated that some 350,000 Americans experience an episode of poison-plant rash each year, I suspect that figure is low. Many people never call their doctors, so it's hard to get a decent estimate.

Green Pharmacy for Poison Ivy, Poison Oak

and Poison Sumac

The traditional drugstore remedy for reactions to poisonous plants is calamine lotion. It cools the hot rash and relieves some of the itching. But personally, I think several herbal approaches work even better.

Jewelweed (Impatiens capensis). I'm not the only fan of jewelweed for preventing the unpleasant symptoms that develop following exposure to poisonous plants. Increasingly, at workshops where I mention it, participants chime in with their own jewelweed stories. I'm well aware that these stories, and my own, are what scientists call anecdotes and therefore are open to scientific skepticism. But seeing is believing. Pile up all the anecdotes, and they make a pretty convincing case.

Of course, experimental evidence is even better. That's why, whenever I teach a three-day class on medicinal herbs, I treat my students to a dramatic little demonstration. I find a poisonous plant, usually poison ivy. I apply its juice to the sensitive undersides of both of my wrists. A minute or two later, I wipe one wrist with a ball of crushed jewelweed leaves and stems. Three days later, the wrist that I didn't treat with jewelweed shows the typical itchy, blistery poison-plant rash. The wrist rubbed with jewelweed invariably shows much less of a rash, and sometimes none at all.

My friend Robert Rosen, Ph.D., a chemist at Rutgers University in New Brunswick, New Jersey, is a whiz at isolating chemical substances from plants. He may have come up with an explanation for jewelweed's effectiveness. Urushiol does its dirty work by binding to skin cells and triggering the rash-producing irritation. A mere one-billionth of a gram of urushiol is enough to affect those who are highly sensitive.

Dr. Rosen has identified the active ingredient in jewelweed as a chemical called lawsone. This substance binds to the same molecular sites on the skin as urushiol. If applied quickly after contact with a poison plant, lawsone beats the urushiol to those sites, in effect locking it out. The simple result is that you don't get the rash.

The greatest concentrations of lawsone are not necessarily found in jewelweed leaves. Although the leaves have some lawsone, there may be more in the reddish protuberances that resemble little prop-roots extending out from the lower stem near ground level. Apply the juice from the crushed red knobs, and you'll probably get better protection.

Aloe (Aloe vera). The gel inside leathery aloe leaves has been shown again and again to help heal burns and other skin problems. Herbalists also
recommend using it to help soothe and heal the rash that follows contact with
poisonous plants. If I got a rash that I suspected came from a poisonous plant, I'd slit open a fresh aloe leaf and wipe the gel on the affected area.

Plantain (Plantago, various species). The prestigious New England Journal of Medicine reported that poultices made from plantain leaves can help control the itching of poison ivy.

Soapwort (Saponaria officinalis). Doctors used to recommend that as soon as you realize you've been exposed to a poisonous plant, you should vigorously wash the area with soap and water to get rid of the urushiol. If you're outdoors without ready access to soap, you can try the juice of the soapwort plant to wash yourself.

I'm singling out soapwort here, but I believe that any of the "soapy" plants that contain compounds known as saponins might work better than soap and water in minimizing the irritating effects of urushiol. Other plants high in saponins include horse chestnut, licorice, seneca snakeroot, soapbark, rose leaves and gotu kola. (Remember, I'm calling for external use of these plants. Horse chestnut and seneca snakeroot are inedible.)