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20 Mar 98

"Poison" Oak

Dunn Middle School climbed 4,000 foot Broadcast Peak in the Santa Ynez Mountains last week. We had great views from the summit of the Santa Barbara back country and the Channel Islands under a gathering storm. We also got seriously exposed to Poison Oak along the way, especially in one place where a small tree draped with still-leafless Poison Oak had fallen across our trail. The statistics after five days: 40% no reaction, 25% some reaction, and 35% major reaction. What kind of "poison" is this that only effects some people? And what is the best way to deal with it?


Poison Oak - Toxicodendron diversilobum

All parts of Poison Oak contain the oil Urushiol that causes the reaction that afflicted our hiking group last week. This is an allergy, not a poison. Poison Oak is one of the most important food plants for deer and other wildlife in our area. Only humans and closely related primates develop the rash. Once the itching starts, "You're gonna need an ocean ... of calamine lotion." Antihistamines and cortisone provide more relief. When all else fails, take a hot shower and scratch all over. It doesn't help, but it feels so good!

Note: The final statistics after our hike were 35% no reaction, 25% some reaction, and 40% major reaction. 60% of those who got it are still scratching after 10 days. This is close to official statistics I've seen that Poison Oak effects 7 out of 10 people. Several kids developed the rash more than a week after exposure, so be warned that the oil can persist for many days. I've also read that no one gets Poison Oak on their first exposure, but they get sensitized and will get it next time. "I don't get Poison Oak" are famous last words!

The kids on the hike contribute the following comments:

"It is an itchy, oozing, crusty mess that looks like whips on my body."
"My own personal, hellish experience."
"The need to itch in my eyeball is imperative."
"Bloody little half moons from clenching my hands and nails - - I will not scratch."
"Putrid pustules disgracing my belly, hands, legs, and neck; insane urges to rip and rage!"
"It was a bumpy, dry rash."
"I want to have my hands tied behind my back so I can't scratch."
"It is an itchy, annoying, crusty and unforgettable experience."
"I couldn't see for three days and I am tired of taking pills. I am so ugly looking."
"I am tired of taking cold showers!"
"Little blisters cover me and I am not being able to sleep at night; I am in agony."
"To itch or not to itch."
"It starts innocently enough, a simple itch one day, a major break out the next. You do everything anyone suggests to arrest and relieve, but still it itches, oozes, spreads and keeps you awake at night!"

I got a mild case on my arms, but I deserved worse since I cleared trail with my bare hands and pocket knife. Next hike, I'll remember gloves and nippers! Oddly, I didn't get it in my scratches.

Pat Dixon sent the following email:

When Syd came down with the stuff (a week later!) - I was reading in one of our self-help books that to achieve temporary relief you get into a warm shower and then gradually increase the heat to the highest temp you can bear, which will cause intense itching (releasing the histamine?), stay in the hot shower until the itching subsides. According to Syd, she was able to sleep in relative comfort most of the night.

My wife Julie tells me that a hot shower feels so good because it triggers a massive release of histamines, the chemical agent in the body that causes the itch. This seems like another stumper since we usually take anti-histamines to stop the itching. But after a massive release, the body's store of histamine is depleted, so there is a period of relief. The feeling is sometimes described as "orgasmic". Julie is not a doctor!

Graybear sent the following interesting email from Virginia:

We don't see much poison oak here, but I'm pretty familiar with its cousin, poison ivy. I have been fortunate enough to have never broken out with it, even though I was a very active hiker, backpacker, and camper both with the Boy Scouts and on my own. Of course, many others around me have gotten it, and my brother is probably the most susceptible person I know.

The 'poison' is an antigenic oil called urushiol. No one is totally immune to it, but some (like me) are much less sensitive than others. Thicker-skinned and hairier parts of the body are less susceptible than others. Metabolism may also play a part, and I've noticed, when hiking, that some people tend to walk to one side of the trail, thus increasing their contact with poison ivy. Your natural body oils help protect you, unless you have recently washed them off.

The best way to deal with it is to not get it in the first place, but if you love the outdoors, eventually you will come in contact with it. If you notice it immediately, you can wash the area with alcohol (soap and water can spread the oil). Once the allergic reaction occurs, 'you're gonna need an ocean - of calamine lotion', but Caladryl/Benadryl is better because of the antihistamines. In the summer, when it's hot and humid here, my brother would soak cloths in an Epsom salt solution and drape them over his body. Remember, too, that the oil can remain on clothing, shoes, pets, etc. for several days, so launder all your clothes when you get home.

I'm curious about using alcohol. Denatured ethyl alcohol from the hardware store has always been my treatment of choice for Poison Oak after the rash appears. It seems to act as an astringent to dry out the rash. Graybear recommends it to wash. But Thomas Fuller and Elizabeth McClintock in Poisonous Plants of California (UC Press, 1986) state that "Oily ointments or alcoholic solutions should not be used, as urushiol is soluble in fats and alcohol." (My emphasis.) What's the answer?

For more information about Poison Oak on the Web, check out Treebeard's Flora.

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Copyright © 1998 by Marc Kummel / mkummel@rain.org