Everything you wanted to know about Poison Oak
Q:Aren't Some People Immune?
people: Those who get Poison Oak, and those who are going to get it. In other words, though there are those who are immune to Poison Oak, their immunity does wear off with repeated exposure. Contrary to popular belief, the more you are exposed to poison oak, the worse the rash gets. You can't become used to it or immune from repeated exposure, the exact opposite is true. Smoking or chewing will not make you immune! It will make you very sorry!
Q:Weren't the American Indians immune to Poison Oak? Did they smoke it to develop an immunity?
Here's how I think this rumour got started: The Indians had been decimated by diseases brought from Europe, their land taken, and forced to live on tiny plots of land called reservations. One day, someone noticed that the Indians never got Poison Oak. This was because they weren't morons, they avoided it! But some white man asked the Indians, "Say, how come you people don't get Poison Oak?" And they though, "Stupid white man, take our land, will you?" So they said, "We smoked it! That's why!" And then big laughs as the moronic whites go kill themselves inhaling a noxious plant.
Western Poison-oak leaves and twigs have a surface oil, urushiol, that is an allergenic irritant. Depending upon individual susceptibility (85% of humans will develop allergic reactions) and exposure, the symptoms can range from trivial to life threatening. The common effect is an irritating, itchy rash, often accompanied with blistering of the skin.
The oil can be transferred from one part of the body to another, from one person to another by contact or by transfer through an object (such as an automobile seat belt), from a pet to a person, or from clothing to skin when clothes are prepared for washing. If exposed, the recommended immediate treatment is to wash the exposed area with cold water, using sand or other mineral soil as an abrasive. Warm water will tend to open pores on the skin and will lead to deeper irritation. Waterless soap has odorless mineral spirits as the active ingredient and will cut the oils before they can spread.
After the oil is removed, the poison-oak cannot usually be spread by contact with an affected area or by scratching. However, scratching can open the skin especially in cases with significant blistering, making it possible for the skin to become infected by opportunistic bacteria (known as a secondary infection).
Effect of Race, Age, Heredity, and Atopic status
In a review, Williford and Sheretz state that the historical notion that blacks are less sensitive to urushiol than whites has not been borne out by published investigations.8 Yet, 50 years ago, Kligman found that in California 53% of whites, 32% of blacks, 28% of Puerto Ricans, and 42% of Hawaiians were sensitive to poison ivy leaves.1 In Philadelphia, he found 54% (223/416) of whites and 42% (383/921) of blacks positive to leaf pressed on the forearm of adults. However, another study in California found no difference between the sensitivity of whites (62%) and non-whites (57%) to urushiol.6 In 1958, Kligman presented information supporting a decrease in responsiveness of individuals by age patch-tested with poison oak leaves.1
Another study comparing a group of 18-25 year-olds with 65-84 year-olds showed delayed onset, diminished peak and prolonged duration in the older group.15 The peak frequency of reactions to urushiol is in the 8-14 year-old age range, and this may reflect both increased sensitivity and increased exposure.7 Maximal sensitivity to urushiol appears to occur between 5-30 years of age, individuals over age 60 years definitely demonstrate a reduced response to urushiol compared to younger individuals.1, 16
Protective clothing is the primary method of preventing dermatitis if contact with Toxicodendrons is unavoidable.34 Remember that vinyl (polyvinyl chloride) gloves are protective, but rubber gloves allow penetration of the antigen.13
Immediate Post-exposure: Soap and Water
Based on the positive results seen in studies performed by both Kligman and Fisher, immediately after suspecting contact with a Toxicodendron, individuals should wash with water (and soap, if available).1, 13, 26 Studies show that the sooner the exposed areas are washed, the lesser the reactions. The potentially contaminated hand that can spread antigen must be washed first.34 While urushiol is not water soluble, it probably physically forces the urushiol off the skin. Additionally, high concentrations of water seem to inactivate urushiol.1 Strong soap and scrubbing merely irritate the skin and are not more effective than mild soap and gentle washing.13 While various authors have warned against using soap with water,3, 8 the concern of spreading urushiol over greater surface areas seems to be theoretical only. The fingernails need to be thoroughly washed, also, as urushiol can remain under them for long periods and remain allergenic.
80% of the population will develop a skin rash when contacting the leaves of the poison ivy plant. The severity of the rash varies from person to person. People between 5 and 20 are the most vulnerable to severe forms of skin reaction. Older persons generally have less severe disease. 10% of people develop very severe skin reactions with major swelling and itching.
How can poisoning from these plants be prevented?
The only true way to prevent this miserable problem is to avoid contact with the toxic oil of the plants. Long pants and sleeves are very important if you are venturing into an unknown wilderness area. If possible, wear gloves, boots and a hat.
Learn to recognize these plants and avoid them.
A new barrier cream called Ivy Block or bentoquantam 5% can be applied to the skin prior to exposure and will form a protective layer on top of the skin. The drug Trental may decrease the rash slightly, but needs to be taken before exposure to the plants. Immunization for poison ivy, oak or sumac is not available at this time.
Avoidance is the key.
What can be done if exposed?
Wash all exposed areas of the skin with cool water. Flowing water is better to irrigate and remove the urushiol oil. Use a nearby stream, river or garden hose if available. If soap is used, wash it off the body and do not spread to other areas.