What I learned about Poison Ivy…

When Nathan and I went up to Charlotte, I somehow managed to get “poison ivy” (did anyone else get some?).

Anyway, being curious, I decided to learn all that I could about poison ivy. My curiosity was piqued when I heard people telling me things like, “Poison ivy is not contagious,” “Poison ivy is actually a chemical burn,” “Poison ivy is actually an overreaction of the immune system (thus, classified as an auto-immune deficiency disorder),” “Poison ivy oil can become air-born in really strong winds.”

Looking online, I found a really comprehensive source of information on poison ivy/sumac/oak. Here is what I learned:

The cause of “Poison Ivy” is an oil called urushiol (you-ROO-shee-ol) – here are some interesting facts about it:

• Only 1 nanogram (billionth of a gram) needed to cause rash
• Average is 100 nanograms for most people
• 1/4 ounce of urushiol is all that is needed to cause a rash in every person on earth
• 500 people could itch from the amount covering the head of a pin
• Specimens of urushiol several centuries old have found to cause dermatitis in sensitive people.
• 1 to 5 years is normal for urushiol oil to stay active on any surface including dead plants
• Derived from urushi, Japanese name for lacquer

From http://poisonivy.aesir.com/view/fastfacts.html)

When urushiol comes in contact with the skin it causes dermatitis, or “inflammation of the dermas (skin)”. There are actually many kinds of dermatitis and the kind you get from poison ivy/sumac/oak is called “Contact Dermatitis”, which

…is a physiological reaction that occurs after skin comes in contact with certain substances. . . . Plant dermatitis is caused by reaction to skin contact with certain plants. About 80 percent of these reactions are irritant reactions and 20 percent are allergic reactions.
From: http://poisonivy.aesir.com/view/pictures.html

So this means there are different sub-types of contact dermatitis:

• Allergic contact dermatitis is a delayed response that triggers an immune response to an irritant.
• Overtreatment dermatitis is a form of contact dermatitis that occurs when treatment for another skin disorder causes irritation.
• Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such as soaps and detergents, solvents, or other chemicals. The reaction usually resembles a burn.

From: http://poisonivy.aesir.com/view/pictures.html

Myth Vs. Fact

Myth	Fact
Poison Ivy rash is contagious.	Rubbing the rashes won’t spread poison ivy to other parts of your body (or to another person). You spread the rash only if urushiol oil — the sticky, resinlike substance that causes the rash — has been left on your hands.
You can catch poison ivy simply by being near the plants	Direct contact is needed to release urusiol oil. Stay away from forest fires, direct burning, or anything else that can cause the oil to become airborne such as a lawnmower, trimmer, etc.
Leaves of three, let them be	Poison sumac has 7 to 13 leaves on a branch, although poison ivy and oak have 3 leaves per cluster.
Do not worry about dead plants	Urushiol oil stays active on any surface, including dead plants, for up to 5 years.
Breaking the blisters releases urushiol oil that can spread	Not true. But your wounds can become infected and you may make the scarring worse. In very extreme cases, excessive fluid may need to be withdrawn by a doctor.
I’ve been in poison ivy many times and never broken out.I’m immune.	Not necessarily true. Upwards of 90% of people are allergic to urushiol oil, it’s a matter of time and exposure. The more times you are exposed to urushiol, the more likely it is that you will break out with an allergic rash. For the first time sufferer, it generally takes longer for the rash to show up – generally in 7 to 10 days.

One of the facts I was most interested in confirming is whether or not poison ivy (i.e. the dermatitis) is contageous. It seems that, in fact, it is only contageous if there is any urushiol oil that has not yet bonded to the skin:

Rhus plants(poison ivy, poison oak, poison sumac) are the most common cause of allergic contact dermatitis in the US. Rhus plans contain the potent antigen urushiol, which will sensitize 60% to 80% of the persons who are exposed to it. …(It) may be carried on the fur of pets, clothing, shoes, toys, tools, or other objects and then transferred to the skin. Approximately 24 to 36 hrs after a sensitized person is exposed to the urushiol, a blistery, itching rash develops. Usually within 15 minutes of contact, the urushiol binds to skin proteins. If it is washed off with soap and water before that time, a reaction may be prevented [and, since uroshiol is an oil, you should use soap that cuts grease, like most kitchen soap]. After the antigen is fixed, however, it cannot be washed off or transferred to other areas. Scratching or oozing blister fluid cannot spread the antigen to other areas of the body or to other persons. New lesions that appear a few days after the primary lesions represent less sensitive areas or areas where less antigen was deposited, not spreading of the antigen. Because the course of the reaction usually is 12 to 15 days, 2 weeks of medication should be prescribed. Reference [Dermatology in Primary Care 1994]

Once bound to cell membranes, urushiol is virtually impossible to wash off and attached to cell membranes becomes a “warning flag” that attracts patrolling T-cells and initiates a full-blown immune response. Reference [Herbalgram (American Botanical Council) Volume 34: 36-42, 1995 by W.P. Armstrong and W.L. Epstein, M.D.]

So…all this to say, I’m glad that I got poison ivy, otherwise I would not have learned so many interesting things about it (actually, I would not have minded NOT getting it 🙂 ). There was a whole lot more information available from where I got the above information. If you would like to learn more, here are a couple links:

• Poison Ivy, Oak, & Sumac Information Center – this is where I got most of my information. Has pictures, product info, remedies and treatments, Q&A, FAQ, Control info, General info.
• Poison-Ivy.org