Poison Ivy: Spot It, Avoid It, Treat It!
“Leaves of three-Let it be!”
If you have ever had poison ivy, you’re probably wondering how you can avoid ever getting it again. The best way to prevent it? Learn how to recognize it. As shown in the image, poison ivy leaves are a medium shade of green with a moderately waxy surface that reflects light. Typically, there are three leaves: the outer two resemble mittens, with the “thumbs” pointing away from the center (third) leaf. In spring, new growth often appears red, while in fall, the leaves turn an orangish-red. The stems also tend to have a reddish color.
Where does it grow?
Almost anywhere! Poison ivy can grow along the ground as independent plants or as vines climbing up trees, sometimes producing leaves all along the trunk or only at the top. These vines may look “hairy” (though other vines can also share this feature). Poison ivy can also pop up in landscaped areas, often in moderately shaded spots like hillsides, under trees, in ditches, or along walls.
Why is it so itchy?
You might have heard that poison ivy is contagious if you scratch the blisters and pop them, causing it to spread but this isn’t entirely true. The itchy reaction comes from an oil called urushiol, found in the stems, leaves, and especially the roots of the plant. It doesn’t easily wash off, and if it gets on your skin, it can trigger a reaction. Using dish detergent can effectively break down the oil and remove it from your skin.
If you scratch it, will it spread?
Not necessarily. If you have not yet carefully washed the area of exposure, the oil can still be there, and then you could spread the oil to other parts of your body. Also, if the oil is on your clothes, boots, gloves, shovel handle, or countertop, etc, you can re-expose yourself to the oil. However, the “spread” with poison ivy is usually not due to spread at all. It is often a delayed phase reaction of the incredible memory of your immune system. In the immune system, there are cells called T cells. It is their job to act as generals in the army of the immune system; they recognize threats and coordinate all the troops of the immune system to fight the threats. When it comes to poison ivy, your T cells think that oil is out to get you, and they are trying their best to fight it off. The problem is that whenever your T cells get attacked on your right forearm, they are not going to forget that. Then two years later, your left arm gets tangled up in the vine and your left arm gets inflamed and itchy after about 1-2 days. Next thing you know, at about day 3-4, your right arm is getting all flared up. This is not spreading, it is the previous site of contact flaring back up because they remember being attacked there before, and those T cells have been sitting there in that right arm waiting for that enemy to come back.
With that in mind, remember to recognize (and teach your kids to recognize) the vine. If you suspect you’ve come into contact with it, just go home straight away and wash that part of your skin with good dish soap, preferably out in the yard so you don’t track that pesky oil into the house. And if that doesn’t work to prevent the itch from starting up, you can always put hydrocortisone cream on the area of inflammation for a few days and keep a watch out for an old area flaring back up. Finally, if you aren’t sure that you touched poison ivy at all, or if the itching is getting out of hand, or you are worried it might not be poison ivy in the first place, go in to see your doctor to talk about other treatment options.
Chris Dodd, MD, PhD is a pediatrician at Cullman Regional. He is accepting new patients and is available for prenatal consultations. To schedule an appointment, call 256-735-5430.