Poison Ivy, Poison Oak, and Poison Sumac, It’s All About the Urushiol

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From Facebook:

How do you deal with poison oak, sumac, and ivy in general?

Scratchy in Santa Fe

Heather says:

If you come into contact with poison ivy, oak, or sumac the most effective “treatment” is to immediately and thoroughly wash the affected area thoroughly with soap and water. All three of these plants (and interestingly their distant cousin the mango) have the same allergenic oil, urushiol. Interestingly, not everyone is allergic to urushiol. While I’m allergic to everything else Mother Nature throws at me, I’ve never had a case of poison ivy despite my years and years of rambling in the woods, but enough about me.

Urushiol Structure So the structure of urushiol looks a bit like this, with alkyl chain at the R in the image. An alkyl chain is simply a bunch of carbon atoms with hydrogen attached kind of like this C/CC/CCH3 (That’s about the best I can do in a standard text editor, just pretend you get it). That alkyl chain makes the urushiol molecule difficult to dissolve in water.

However your skin has oils and urushiol will gladly hang out in those oils, having a party, raising blisters and an ugly rash.

The urushiol can be spread through contact, if you have some on your arm and you scratch, you may get the urushiol under your finger nails which will then be spread to your face or wherever you decide to touch before you wash. (And gentlemen, I’ve heard plenty of embarrassing stories about men not washing their hands thoroughly and -how do we put this delicately- spreading the fun to less public body parts and later assuming they have other issues that require a visit to the county health department.)

Despite the persistent old wives tale, you cannot spread poison ivy from the rash itself, UNLESS, that rash never got washed and still has urushiol. Got it?

If you don’t wash the oil promptly your skin may absorb the urushiol; which, as you can imagine may intensify your reaction. Some people even have systemic (whole body) reactions to poison ivy and will break out in rashes, even in places that have not had contact with the irritant.

Keep in mind that animals that have come in contact with poison ivy, oak, or sumac may spread the urushiol on their fur. If you’re especially sensitive, try to keep animals off of the furniture (especially beds) and bathe them thoroughly.

When removing poison ivy, sumac, or oak from your property, your best defense is to wear long pants, long sleeves, and gloves. Take this clothing and immediately place it in the washer – check out How to Remove Poison Ivy from Clothing, and wash your hands thoroughly. That’s it. There’s no magic trick. Sure there are plenty of products out there that claim to work especially well, but that’s mostly marketing. Wash the area with plain old soap or dish detergent (for hand washing, not the stuff you put in your dishwasher) and then treat the rash itself with your favorite OTC topical ointment.

Oh and a very important side note: Never burn poison ivy. That rash you get on your skin? It’s nothing compared to a potential reaction in the lungs.

Send your questions to helpme@home-ec101.com.

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14 thoughts on “Poison Ivy, Poison Oak, and Poison Sumac, It’s All About the Urushiol”

  1. How interesting that mango is related to these poison- plants!  I’ve never understood why I’ve been so sensitive to everything poison- and mango! Thanks for mentioning the distant cousin!!

    • Urushiol is found in the peel of mangoes (as well as the bark and leaves of the plant). If someone else cuts off the peel, you should have no problem eating the mango pulp.

  2. One thing I would add… when removing it from your property, if you intend on using a weed wacker, be sure to wear some sort of pants that it can’t get through (not jeans etc). I find windbreaker pants work well. If you forget that, the weed wacker can and does fling the plant all over and the oils can get through the jeans or whatever. My mom had that happen and pretty much everything below her knees was just awful.

    I also like windbreaker pants if you know you’re going to be hiking through stinging neddle as the oils can get through jeans as well.

    Is stinging neddle related to poison ivy etc?

    • No, nettle is entirely unrelated. The nettle plant has fine hairs that contain formic acid, which is the same chemical that makes ant bites sting. Neutralize it with ammonia or baking soda, or anything sold to relieve be stings. Even untreated, it will stop hurting in a day or so.

  3. I had no idea that there was a poisonous variety of Sumac.  Here in my corner of the globe, we use it to flavour rice and kebab, and it adds a nice tartness to green salad.

    • Poison sumac (with white berries) is only distantly related to the edible sumacs (all of which have red berries). In North America, Native Americans steep [edible] sumac in water to make a lemonade-like tea.

  4.  @nezume
     And of course, don’t use a weed wacker on poison ivy (or on anything, really) wearing shorts and a tank top. Unless you’re me.
    Yeah, that took a while to get over, mostly because it took me a while to figure out what it was. It didn’t look like any other poison ivy rash I’d ever had — of course, that’s because the plant was chopped into bits and flung all over my skin, so it was quite different from the typical pattern you get from brushing against the leaves. D’oh!

  5. I was interested in the chemical structure which brought me here. I’ve had poison ivy, oak….and just recently found out what sumac is and now looks like – a bit late, as my legs are on fire!  I’m about to  go take a mud bath. I’ve tried many store bought remedy’s and a bunch of home remedy’s. I just wanted to share my 95 yr old fathers last words to me: (I was broke out bad when caring for him) he said, “when I was a boy we just used mud”.  WOW this works!  as the mud dries it draws the oils out of the skin  and after a day or two of repeated mud baths you are left with really soft skin too. If yard mud is too gross for you, the women’s facial mud packs in the store work pretty good too. 

    • Son of Joseph M Ott,

      Thank you for sharing your story and your father’s last words! Very good advice. The Lord bless him and you.

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  7. Jewel weed is good at fixing poison ivy. Just smash up the weed and rub the juices on the affected area, the rash will clear up right quick. 🙂

  8. One warning–if you are susceptible to these things, don’t burn the trash from cleaning it out of the yard!! I lived down wind from someone who burned wood that had poison ivy on it. Absolute worst case I’d ever had, and required a doctor visit, steroids, and other fun things. That was the only way I could figure out I got it because there was no other exposure method possible, husband wasn’t out in the woods (I definitely wasn’t) and no pets.

    That’s another way you can be exposed, by the way, pets can get in it and rub it off on you and bedding, etc. That was another bad case, doctor visit, etc. We gave up and used poison to get it out of the yard. And one of our dogs had to go on Benadryl to clear up their rash, and get a much hated bath! (Yes, it is safe for dogs in a careful dose.) And this was in the middle of a big city, that stuff grows everywhere! I’ll remember about the mud baths next time, and there is always a next time.


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