Poison Oak

Whenever you travel along the California coast, you should be aware of one potentially annoying hazard that seems to be everywhere. It's a plant called Poison-oak (Toxicodendron diversilobum). While most people have heard of this common plant, it's surprising how many folks cannot identify it in the forest.

It's also interesting to note that the American Academy of Dermatology estimates that there are approximately 50 million cases annually of “urushiol-induced dermatitis”, which is the allergic reaction caused by Poison-oak, Poison Sumac, and Poison Ivy. It's also thought that  approximately 10% of all lost time injuries in the U.S. Forest Service are caused by these same plants.

We've heard many different tales about the way Poison-oak spreads. Some of it is true, and other stories seem to not be supported by available facts.

Is it Contagious? - One story that keeps surfacing is that Poison-oak is contagious. While it's true that Poison-oak can be spread by contacting the clothing of someone who was exposed, or by touching an animal that was in contact with the plant, it's important to remember that Poison-oak is not a disease. It's a “contact allergen” that brings on an allergic reaction to approximately 90% of the people who are “exposed”. In most cases, exposure to another person's skin will not cause a reaction once the oil has been washed away. Also, any fluids that may develop from blisters associated with the Poison-oak induced rash will not cause further spreading. A spreading rash is usually caused by different levels of exposure rather than a spreading condition.

It is said that you can get Poison-oak simply by being in the vicinity, especially downwind – This might be true in extreme circumstances, but our research seems to indicate that direct contact with the oil on the leaves, or more accurately, the “oil FROM the leaves”, meaning that  secondary exposure from clothing or animals can also cause a reaction. Simply being in the vicinity for nearly everyone is not enough exposure to cause a reaction.

One exception to this is exposure to smoke from burning Poison-oak plants. This is actually a concern among firefighters in California as they battle coastal mountain and Sierra Nevada foothill fires. Smoke from the burning plant leaves can cause the oil to become airborne, resulting in exposure by simply being in proximity to the plants. This is especially hazardous if a firefighter inhales the smoke. The allergic reaction that occurs on your skin happens the same in your lungs, but with much more serious results. Exposure to Poison-oak smoke can be fatal if inhaled.

How does Poison-oak Work? - Poison-oak, Poison-ivy, and Poison Sumac all contain an oil on the surface of their leaves called urushiol, which is a compound that causes the allergic reaction. This same oil is also found on the outer husks of Cashew nuts, and in the sap of the Mango. When a person comes into contact with the oil “urushiol”, it actually bonds to the skin after a few minutes, and cannot generally be washed off. An allergic reaction can occur within a few hours, but can also take as long as ten days, depending on the amount of exposure and the degree that an individual is allergic to the oil. Some people will not display allergic symptoms, but can and often do develop sensitivity after repeated exposures.

What does it look like? - There used to be two sayings in the official Boy Scout Handbook. “Leaflets three, let it be,” and “berries white, poisonous sight.” Poison-oak is usually found along the California coastal hills, but can be found anywhere on the west coast from Baja California to British Columbia. In the higher mountains, it is normally found below 3,500 feet in elevation. It grows in small bushes, but can also appear as a vine and travel up existing trees. The leaves are normally in groups of three leaves that are about 2 1/2 inches long and look distinctively like oak leaves. The colors of Poison-oak leaves range from green to red and even pink, depending on the time of year. The leaves are generally oily in appearance compared to normal oak leaves, although common scrub oak leaves can also appear oily in the spring. Sometimes, Poison-oak has little white berries on the stems. It's sometimes hard to tell the difference between Poison-oak and small Oak bushes (scrub oaks), but one effective method to avoid a problem is to simply stay away from both.

First Aid – There are a number of remedies available, but the most reasonable course of action seems to be: Wash the exposed area immediately with soap and water. Immediately seems to imply within fifteen minutes of exposure. If no soap is available, use plain water. Urushiol is not water soluble, so use as much water as you can to attempt to literally wash it away. Use cold or cool water when washing. Seek medical attention from doctor or dermatologist. Many of the most effective treatments are not available over the counter, so a prescription will be helpful.

If your clothing is exposed, be sure to wash them in a good strong detergent separate from other clothing. You have more time to wash clothing since the oil will not chemically bond.

Finally, when in Poison-oak country, remember that even though poison plants lurk everywhere, don't get too worked up about it. Poison plants, insects, reptiles, or whatever, exist almost everywhere you go. Just pay attention to where you are and what you're doing, and have a good time.