Episode 7: March 23, 2010
by Rob Lamberts
Last time we talked about swimmer's ear, a common summer malady. In today’s articIe am going to talk about poison ivy, a spring and summer skin condition that can make the season a little less blissful.
What Is Contact Dermatitis?
The skin problem I am covering in this podcast is called contact dermatitis. The word dermatitis means: “something is messed up with the skin.” Rashes are sometimes difficult to identify. The only way to diagnose what causes a rash is to look at it and hear the story of how it got there. There is no rash-o-meter that you can put on it to tell you what it is, so it’s not uncommon for rashes to befuddle doctors. When this happens, they usually diagnose it as dermatitis. That is cheating, really, because the patient already knows that there is something messed up with their skin. I’ll let you in on a common doctor trick: using a Latin or Greek word is a good way to sound smart when you don’t have a clue.
Contact dermatitis is a rash that happens because of contact with certain substances. Fortunately, it’s usually not very hard to identify. The most notorious cause of contact dermatitis is the dreaded poison ivy.
What Is Poison Ivy?
Poison ivy (and its partners in crime, poison oak and poison sumac) is a plant that has oil on its leaves. Some people develop an allergy to this oil, which results in the typical poison ivy rash. There are a number of other less common substances that can also cause contact dermatitis, including Neomycin (a common skin antibiotic), nickel (which is present in many belt-buckles) and something called Balsam of Peru. I don’t know what Balsam of Peru is, but I advise avoiding it if you can.
Contrary to what I learned as a kid, there is no difference between the rash caused by poison ivy and those of poison oak and sumac. The typical rash from contact dermatitis is red, raised, sometimes blistering, and very itchy. It also occurs in crops or patches on the skin rather than in a generalized rash. That is because the rash only happens where the skin has contacted the offending oil.
How Do Rashes--Like Poison Ivy--Spread?
That is a really important point when dealing with contact dermatitis. Most people believe that it can be spread by scratching and spreading the fluid in the blisters. That is not true. The only way the rash can spread is if the oil from the plant spreads to new parts of the skin. There are several ways for this to happen:
The person doesn’t believe in personal hygiene or has a religious objection to using soap. Soap makes oil dissolve in water and wash down the drain. Soap is your friend.
They enjoy the rash so much, they go back and touch more plants to maximize their fun.
The towels, shirts, coats, and bed linens get some of the oil on them and so spread it to different body parts. Watch bands and eye glasses can also carry the oil.
Bowser the dog rolled around in a field of the plants and is spreading the joy with his affection.
When Do Rashes Show Up?
The problem is that the rash shows up 12 to 24 hours after the contact. That means that people will repeatedly expose themselves to the oil before they know and regret it. A lot of exposure can happen in the window of time before the rash shows up.
Why Do Some People Get Poison Ivy Rashes but Others Don’t?
You may have noticed that some people could wear underwear made of poison ivy without developing an itch, whereas others get a rash whenever someone says the words “poison ivy.” That is because of it being an allergic reaction. Some people are much more allergic than others. Those in the latter group should become experts on what these plants look like. I’ll put a link to pictures of them in the show notes.
How Do You Treat Poison Ivy Rashes?
It's a myth that you can get poison ivy from touching the rash on someone else; don't believe it.
The rash from poison ivy can last for several weeks if left untreated, so I do recommend treating it once it comes up. For mild cases, simply putting over-the-counter hydrocortisone cream on it will help it go away. Calamine or Caladryl creams are often used, but they are not as effective as cortisone at getting rid of the rash (although they’re great for people who like pink spots on their skin). Oral diphenhydramine (also known as Benadryl) will help with the itch and allow sleep.
If the rash is widespread or it has spread to the face, treatment with an oral steroid like prednisone may be needed. That is generally safe in children and adults if used for short periods, although it can make people act goofy and retain fluid. Like any medication, prednisone should only be used when the benefit outweighs the risk. The biggest benefit to treating poison ivy is sanity.
Quick and Dirty Tips for Poison Ivy
Here are my quick and dirty tips on dealing with contact dermatitis:
Tip 1: If You Get Contact Dermatitis, Wash Everything. - Towels, sheets, and pillowcases are the biggest culprits of spreading the oil. If your rash is spreading, you are being exposed to the oil somehow. Remember that the rash does not spread by scratching it (although it can get infected by scratching too much).
So Wait…does that mean that you can’t get poison ivy from touching the rash on someone else? Yes, that’s exactly what it means. It’s not true. It’s a myth spread by the CIA in the 50’s. Don’t believe it.
Tip 2: For Mild Rashes, use Hydrocortisone - Other treatments might help with the itch, but steroid creams will treat the allergic reaction itself.
Tip 3: See your doctor for bad rashes, or ones that you aren’t sure about. – Rashes to the face or rashes that are widespread may need oral steroids to get better. Also, be aware that other rashes, such as shingles and even herpes, can sometimes look like contact dermatitis. Again, if you are not sure, see your doctor.
Remember, this article is for informational purposes only and is not intended to provide you with medical advice or recommendations for treatment. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.
That’s it for today.
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Catch you next time! Stay healthy!