Infectious Poison Ivy?

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My sister called me this week to get sympathy about her persistent poison ivy rash. I suggested that the poison ivy might be spreading through her bloodstream—a diagnosis I’d received many years ago from a doctor after a severe case of poison ivy that made my entire face swell up like a boxer who went three rounds with Mike Tyson. My sister laughed and told me that was a myth.

“No way. I heard that from a doctor,” I said. I didn’t tell her it was thirty years ago when the doctor told me this.

Amazing how some myths can be so persistent. When we hear from a trusted source, we believe and don’t question. That can be a good thing, if the trusted source is God, but anyone other than Him shouldn’t be put on a pedestal of perfection. Everyone gets it wrong sometimes or at least doesn’t have all the information.

So of course I had to do the research on poison ivy and I found more myths out there than I would have thought. Here are some of them. Maybe you’ve been believing these, as well.

MYTH #1: Poison Ivy can spread through your bloodstream.

As a scientist, it hurts to admit I believed this for so long, but poison ivy does not spread through your blood. You must come into direct contact with the urushiol oil on the plant to get a rash. Many of us start out immune to this oil, but become sensitive to it through exposure, which stimulates our immune system. Most people develop sensitivity to the plant in their teens, but there are some people who never develop this sensitivity.

MYTH #2: You can get poison ivy just by being next to the plant without touching it.

To get poison ivy, you must come into contact with the urushiol oil, which then irritates your skin. This means direct contact from the plant or from other sources, like your dog’s fur or the pair of pants you wore or the hedge clippers you used. The only exception to this is when poison ivy is burned because then, the oil can become airborne on the particles of smoke and spread poison ivy to the eyes, mouth and respiratory system. Please do not burn poison ivy.

MYTH #3: The blisters caused by poison ivy can spread poison ivy to the rest of your body.

Actually, the weeping blisters are your body’s reaction to the urushiol oil and they contain no oil inside them (because the oil has already been absorbed into the skin). Even by itching the blisters and breaking them open, you can’t spread poison ivy to other parts of your body.

MYTH #4: Poison Ivy can’t cause a rash after the leaves fall.

All parts of the plant (except maybe the pollen) contain the irritating urushiol oil, therefore you can get a rash by coming into contact with the base of the plant after the leaves have dropped.

MYTH #5: If you eat poison ivy, you will eventually develop immunity to it.

This one shocked me. I’d never heard of eating the plant, but apparently some people have advocated this. Please do not do it. This can be at best irritating to your system and at worst can cause a fatal allergic reaction.

You might be wondering why the rash appears to spread if it can’t spread through your blood or by the blisters. This is because different areas of your skin have a different thickness and therefore take longer to develop the rash. For instance, few people develop poison ivy at all on their fingertips because the skin there is so thick. The oil can continued to penetrate and irritate your skin for one to two weeks. Also, you may be coming into contact with the oil on items you wouldn’t suspect. In my sister’s case, she discovered it was likely her shower puff.

Now that we’ve reached the summer months, be on the look out for that irritating three-leafed plant (see picture above). And for goodness sakes, don’t eat it!

 

References: http://www.webmd.com/skin-problems-and-treatments/guide/understanding-poison-ivy-oak-sumac-basics, http://extension.psu.edu/pests/ipm/pestproblemsolver/house/lawn-landscape/weeds/poison-ivy-myths, http://www.medicinenet.com/script/main/art.asp?articlekey=158752&page=2

Photo Credit: N03/3565493876″>Poison Ivy (Toxicodendron radicans) via photopin (license)

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