Poison Oak

The following is from Santa Barbara Day Hikes by Ray Ford

I’ve discovered an amazing thing in the years I’ve been hiking in the Santa Barbara area—the people who are the most susceptible to poison oak (to me it’s simply “oak”) are the ones who seem least likely to recognize it. I’m not sure why that’s true but it is. I’ve got a friend who is so allergic to it that he starts breaking out just by looking at a picture of it in a book. You would think he’d have antenna by now that could pick it up like radar, warning him when he’s within a half mile of it.

But when we are out on a hike and I hear him say, “Gee, what’s this?” I don’t even have to look—I know he’s in the oak again. You would think after a while that he would finally learn his lesson.

There are probably more myths concerning poison oak than just about any other backcountry problem. No you don’t get it from scratching. The mugwort probably won’t work. No, it can’t get in your bloodstream and spread. Yes, you can get it from the branches, even if all the leaves have fallen off, as in the wintertime.

Simply put, you get poison oak by coming into contact with the offending bush, whether in leaf or stick form. What causes the irritation is the oil, a sappy, whitish liquid known as the Rhus antigen, which was named after its discoverer. All the plants which cause this reaction (such as poison oak, poison ivy, or sumac) have the same basic oil. The reaction to all of them is known by the same name—Rhus dermatitis.

Only those areas which come into contact with the oil will react and only to the extent that they are sensitive to it (why some people have sensitive skin and others don’t I will never understand. I’m just glad I’m not). While the ability to react is somewhat determined by genetics (if your mom and dad get it you probably will too), repeated contact with the oil can increase your sensitivity. If aren’t allergic to it now, don’t brag about how you can crash right through the stuff. You may regret it later.

Contact can be direct, from the plant leaves and vines, or indirect, by coming into contact with the oil at a later time, either from contaminated clothes or perhaps from man’s best friend—your dog. An absolutely awful way to get it is through inhalation of the vapors, such as from a trash fire or while sitting around a warm, toasty campfire stoked by someone’s careless use of of poison oak for kindling. Ever thought of what oak might be like on the inside of your mouth or throat? Or to wake up in the morning with your eyes swollen shut? Once the rash breaks out (usually in about 3 days) scratching will make the blisters run but the fluid release by your incessant itching is serum, not the Rhus oil. You might infect the area but you won’t cause the oak to spread. 

Surprisingly, neither antihistamine creams nor calamine lotions stop the reaction. All they do is help keep the itching down and help stop the fluid from running once you’ve started scratching. If a few blisters do appear after a trip into the mountains, they can be treated with any brand of over-the-counter cortisone cream and a good antihistamine, such as Benadryl (dephenhydramine). The rash should be gone in a week. If not, consult your doctor.

What should you do if you think you’ve made contact with this obnoxious plant (there must be some reason of its existence, but though I’ve tried, I haven’t come up with one yet) there are a number of things you can do. First of all, get the clothes you were wearing off as soon as is practical and keep them separated. Then take a long shower, starting off with as cool water as you can handle (this helps keep your pores closed), and wash yourself as thoroughly as possible. Wash your clothes by themselves with a potent detergent—cycle them through twice if you want to be sure to get the oil off.