Poor, Misunderstood Poison Ivy


[♪ INTRO] Nothing can ruin your vacation quite like an encounter with one of nature’s purveyors of itchiness. Of course, I’m talking about poison oak,
poison ivy, poison sumac, and their notorious relatives. Yes, these botanical nightmares are clearly out to make camping and hiking as miserable as possible. But maybe they’re not? Maybe they were just hanging out in the forest,
enjoying the fresh air, and trying to keep harmful microbes at bay, until you and your over-eager immune system
happened to come along. Poison ivy and the like are innocent. These plants all produce an oily resin called
urushiol. And it isn’t just in their leaves; it’s
in every part of them. And it remains even after the plant has died. This urushiol is what causes that notorious
itchy rash you get, or, what doctors call “urushiol-induced contact dermatitis.” Now, the leaves have to be crushed or somehow damaged in order for the urushiol to actually contact your skin, so you won’t get it by
just touching the plant. Of course, leaves and such are easily damaged
by insects, passing animals, or a stiff breeze, so just because you didn’t damage the leaves
yourself doesn’t mean something else didn’t get there first. In fact, because urushiol causes such a violent
rash in people, there’s this pervasive idea that the resin evolved as a defense mechanism
against large mammals like us. But that’s not true. Or at least, if it was a defense mechanism,
it would be a really lousy one, since urushiol doesn’t bother most animals that encounter it. Just us and apparently, hamsters. But it has no effect on the animals that actually
feed on the plant, like deer, insects, and birds. That’s why scientists think it’s more
likely that urushiol evolved as an antimicrobial, it’s quite effective against much smaller
plant pests. There’s even been some speculation that
birds that eat the seeds actually benefit from urushiol’s antimicrobial and anti-parasitic
properties. It’s simply an unfortunate accident of evolution
that makes these plants incompatible with humans. So, the rash, oozing blisters, and relentless
itching, it’s all pretty much down to cosmic unfairness. Urushiol interacts with your skin cells; specifically,
ones that express a protein called CD1a. CD1 proteins help the body spot invaders and
sick cells. They bind to specific fats, then show those
fats to the body’s immune cells. Except, human CD1a has the unfortunate tendency to set off attacks in response to things
that aren’t pathogenic. And it just so happens urushiol is one of
those things. Urushiol-loaded cells activate the body’s
T cells, those vigilant warriors of the human immune system. Then the T-cells release two proteins called
interleukin 17 and interleukin 22, and they’re what make you itch. The redness, swelling, and blisters all occur
because your immune system harms your skin cells in its attempts to eradicate a bit of
harmless oil. Now of course, this doesn’t really apply
to those 10-15% of humans who don’t seem to be affected by urushiol at all. For some reason, nature has seen fit to spare
some people from the horrors of urushiol, but there hasn’t been a lot of scientific
research into why that is. It might be because urushiol-induced contact
dermatitis is basically an allergy. And allergies occur when the body mistakes
a harmless substance for something harmful. And like with other allergies, some people’s immune systems just go haywire when encountering urushiol while others’ don’t. It’s just that most people are allergic
to urushiol. But also, some of the people who say they’re
immune probably aren’t really immune. Most people don’t react to urushiol the
first time they’re exposed, so a person might believe they’re immune when, in fact, they could go on to develop
an allergic reaction if they touch it again. And even if they’ve had a couple of exposures
with no reaction, they could still develop a sensitivity later in life. And increased exposure is thought to increase
the likelihood of developing sensitivity. So if they roll around in a bunch of poison
ivy to show off to their hyper-allergic friends, they might end up experiencing some itchy,
itchy karma. Though, weirdly enough, sometimes sensitivity
to urushiol fades as people get older. Scientists aren’t really sure why, but it
might have something to do with the fact that your immune system weakens as you get older. And a weaker immune system may not mount as
strong a defense against urushiol. So that’s one advantage to getting older! At any rate, whether you think you’re immune
or not, or may have become less sensitive over time, you probably don’t want to push
your luck. Urushiol-induced contact dermatitis is miserable
at any age. So it’s always a good idea to avoid whichever
version of poison-whatever is in your neighborhood. If you want to learn more about the quirks
of human immune systems, you might like our episode on how having parasites
could actually be good for you. And of course before you go, be sure to click
that subscribe button and ring the notification bell! Ding! Ding! Ding! Ding! Ding! Ding! Ding! [♪ OUTRO]

100 thoughts on “Poor, Misunderstood Poison Ivy”

  1. There's poison ivy in my yard, (2 out of 4 sides have trees, enough of them that they can't be seen through) and I used to wonder those woods for hours as a kid.. I never once had it bother me. My dad went through my trails once and his legs were covered. 🤷🏼‍♀️

  2. i used to get poison ivy all the time. poison oak a few times, once in my eyes. heard sumac was the worst but never exposed to it. i am going to assume wearing pants and long sleeves outside helps a whole lot

  3. I was very sensitive to it when I was young. In my teens I developed a resistance to it, to the point that I have to have a significantly large exposure to have a mild, limited reaction. Likely simple repeated exposure is what helped, being that I spent a lot of time wandering around in wooded areas as a kid.

  4. "Having parasites can be good for you" Well capitalists have been saying that ofr a while tho they call them sharholders 😀

  5. i once used poison ivy berries to make "green paint" as a kid by mashing it up and wiping it on everything around the backyard. with bare hands.

  6. I don't react to poison ivy / oak and neither does my mom. Never run into sumac. I know I have a weak immune system though so SHRUG

  7. If anyone is familiar with Urushi lacquer, it comes from a type of Japanese poison ivy I believe. Craftsmen who use it have been known to become desensitized to it over time, that's what people say at least… any studies that focus in people who work with Urushi lacquer for years?

  8. My father is completely immune to it and has been since he was a child. I have been at the very least resistant to it my entire life. I live deep in the woods and walk trails right now I literally have some growing up my porch that a rip off every few weeks when it grows back up. Never had a reaction to it. My oldest brother complete opposite man literally gets hospitalized if he barely touches it. My father to this day could probably eat it without any effect besides complaining about the taste. I hope I'm of those in the 15% range that never developes an allergy to it because that would kinda suck and the genetics are a toss up for my family. Some are fine others go to the hospital. Do it could go either way

  9. I’ve never had contact dermatitis from poison ivy, poison oak, or poison sumac. I love the outdoors. I love to hike, swim, fish, hunt, and camp. I am not bragging (I promise ) but I can pull the stuff up without a glove on. I make up in other things to take the place of this immunity, I have eczema and psoriasis which is a pain and stays with you were contact dermatitis does go away.
    When I was younger around, 10 or so, my dad loves to hunt and every season came in contact with poison ivy. Seems like he could walk by the stuff not touch it and still get it. So I asked my mom why we (my mom and myself) didn’t get poison ivy? She said that she asked her mom the same thing when she was young and my grandmother told her that it has to do with my great great great grandmother being full Cherokee Indian. Meaning they were native here and over time built an immunity to it. I understand there’s no scientific evidence to back this theory up but it makes sense to me. Maybe scientists should start with Cherokee Indians. Live and let live, it’s interesting and amazing that animals and insects can eat poison ivy and have no effect negative effect on them

  10. watched video – googled – nice:
    These data provide evidence that urushiol has the potential to be used as a chemotherapeutic agent in human gastric cancer.
    Keywords: Urushiol, Gastric cancer cells, Apoptosis, G1 arrest

  11. As a kid, I was moderately allergic to poison ivy/poison oak. As a young adult, I went hiking and fell into a large batch. No reaction. I've tried to test it a few times, no response. Is nice

  12. "increased exposure is thought to increase the likelihood of developing sensitivity" 3:16
    I will have words with Dwight Shrute.

  13. No idea if I am reacting to those plants…
    but funny enough, I react to saw dust.
    Wood itself do nothing but if I am in contact with fine saw dust,
    my skin got all red, swollen and itchy.
    This is nothing dangerous but kind of annoying.

    I still prefer that over dangerous allergy or food allergy.

  14. As someone who is highly allergic to urushiol and has been told by their doctor that I'll have to carry an EpiPen if I come into contact with it again, I can say, screw the whole toxidendra family.

  15. I’ve never gotten poison ivy rashes in my life. I’ve always wondered why that was. Maybe I’m immune myself. I wonder how I can find out. I don’t even know how to identify the stuff in real life.

  16. I had the misfortune of working in an area of bush without seeing it in daylight. In the middle of the night I had to find an inconspicuous place to have a pee. I hid behind a tree and had to push some bush away so I could relieve myself. A few days later I realized that it must have been poison oak around that tree. Needless to say the rash was not limited to my hands

  17. “Poison ivy is innocent”

    my systemic autoimmune reaction and several patches of severe scars would like a word with Scishow.

  18. Well perhaps I should stop rolling in the stuff to win a game of tag I've never been affected by it but one day I might

  19. For years I could touch and cut that stuff without issues… this year it started to give me blisters. Seems like the poison ivy finally got through to my immune system 😛

  20. Im immune! Everyone told me i was crazy but I've never gotten a rash from poison ivy, just a sensation of warmth that fades about an hour afterwards

  21. My brother was a psychopath, and when we were little, he took a handful of poison ivy leaves and rubbed them all over my face. Turns out, I don't have a reaction to it, and he's hypersensitive. He wound up having to go to the hospital and take a course of prednisone because the swelling was so bad that it started cutting off circulation to his hands, and I didn't get so much as a bump. Ahhh, sweet sweet karma.

  22. Luckily I'm not effected by it I live in the woods for like 12 years and I've ripped it off trees burned it walked through it and everything and never had any sort of bump on my skin aside from mosquitoes.

  23. I'm deathly allergic to poison ivy. If I get it bad enough (and it doesn't take much at that), I have to go to urgent care. The doctor told me I was the worst case he ever seen in 30 years of his career.

    We have neighbors use their goats to eat all the poison ivy/oak in the woods so I can get near it. Only thing is I can't touch the goats afterwards or it's another trip to urgent care the next day.

  24. "it's simply an unfortunate accident of evolution that makes this plant incompatible with humans." Oh you arrogant humans. It is no accident.

  25. When I was 10 I rolled in a large patch of poison ivy while in my bathing suit to prove I was immune to a friend. I had no problem at all. 12 years later I sat in poison sumac by accident… The resulting month of not being able to sit was excruciating.

  26. Soooo. I can literally roll in the stuff and not get any rash/blisters, but anyone I come in contact with breaks out severely.
    I pull the stuff up with my bare hands and even get sprayed in the face when pulling and I don't have a tight enough grip and my hands zip up the vine…
    My mom will get HUGE GIANT blisters from ME, while I get no reaction. Now Mosquitoes… they scar me. I have scars from Mosquito bites.

  27. i'm curious. can't videos like this be made without the worthless senseless verbage? i mean hearing the word t cell and cd1a does not help me even a little tiny bit. at all. and the part about evolution is not necessary at all. you could just as easily say made by god, but since your god is evolution you say evolution. so without all the unnecessary verbage how long would your video be? hint: you made your A in poison ivy 101, but your're not in class anymore. you sound to me like you're trying to re-win your A in biology class. i watched the whole vid. it could easily have been reduced to 2 minutes. and it would have been better if you covered what to do after contacting poison whatever. p.s. i don't get the itch. i'm also rh- blood type so i don't get a lot of things you lesser beings get. life is good. life is real good if you're not an eathling with rhesus monkey blood..

  28. I was crazy allergic to poison ivy as a kid.i would get it constantly on every inch of my body.
    Now I can handle poison ivy and I don’t get much of a rash from it now.

  29. As a kid I got poison ivy often
    Usually it wasn't a big deal, once it was so bad I became covered with dime sized blisters, not itchy painful
    I was 40% covered with horrible blisters, forty % is a massive part of the body
    Doctor put me on talwin a pleasant narcotic

  30. I was extremely allergic to poison ivy as a child. Got a severe case of it every summer. I didn't even have to touch it. I would get it if it rained and the oils were in the air. I seemed to have become less allergic as I got older but not old. I have not been exposed to it in years so I don't know how it would affect me now.

  31. When I was a kid I use to walk in the forest barefoot. I did not know what poison ivy was till after I walked threw it many times and it did not bug me.

  32. I grow poison ivy and from time to time apply it to my skin on purpose. Now that may sound a bit crazy but a nice rash on say your forearm placed under the the hottest water you can bear produces a euphoric effect. At least for me, anyone else ever experience this?

  33. So you're saying Nigel Thornberry didn't induce an immunity to poison ivy through allergen immunotherapy? (Specifically by rubbing it all over his body). I feel lied to be 20 year old kids cartoon.

  34. I can only go by my experience. Grew up climbing poison sumac and never broke out, to this day. On the other hand, I use to be allergic to poison ivy til I was about 7 yrs old. I had a break out on my leg and woke up the next day to my face being swollen and I could barely see. Ever since that break out, I've never had a break out since with poison ivy. So I think the body can build an immunity to it like it does with other things. But nice info in the video.

  35. Always find out ahead of time if you have Poison Ivy in your neighborhood before trying to pull "weeds" in your yard! I found out the hard way!

  36. I always loved playing in the poison sumack bushes behind the shed as a kid, and did not know it was an itchy plant until a friend came over to play and got it everywhere. I'd never gotten poison ivey or poison oak before either but not sure if I'd been exposed to those, so if you're not sensitive to one you're not sensitive to any?

  37. Woohoo part of the 15% I've picked poison ivy and oak out of gardens and firewood respectively. And it doesn't bother me a bit.

  38. So, in theory, scientists could develop a derivative which we ingest for the antimicrobial properties?
    Who wants to be the first to try that new drug out?

  39. Interestingly from what I've read Urushiol oils are produced by all kinds of plants within the Sumac family including Cashews Pistachios and Mangos etc just not in the same concentrations as Poison Ivy (though Cashews if memory serves need to have their fruit made into jam and seeds roasted to be edible without nasty rashes And I know someone who has had nasty reactions to mangos

  40. My ex once went out to collect wood for the fire but ended up picking up poison oak , then when he was placing the wood and attempted to light the fire he dislocated his knee. He was such an idiot. And honestly this was the icing on the cake of a long list of stupid actions during camping.

  41. Urushiol is also in mango skins. I did not know this until I found out for myself. I'm extremely allergic to Urushiol and boy, was that fun! My lips were nice and swollen and itchy. 😑 Hope this saves someone the trouble.

  42. Aaah, our tiny brethren, the ignoble Hamster. We both handle urushiol abominably. Neither we nor they can make our own Vitamin C. And we're both are fond of carrots and warm places to sleep, generally speaking.

  43. You all make great content. I'd like to tip this channel some BAT (Basic Attention Token) but you're not registered yet. If you want to join the BAT/Brave ecosystem, I think it's fairly easy to https://creators.brave.com Thanks for all the great videos!

  44. Because of some construction, and repair projects I woorked on I have been exposed to the damaged roots of poison ivy many times. Like the kid said I wouldn't push may luck.

  45. Would a dairy intolerance or peanut allergy get lighter as your immune system weakens and you get older in the same way as this allergy does?

  46. I grew up being told that drinking (spring) water that had run through the roots of poison ivy/poison oak gave immunity to them. I can't say how much truth that legend holds, but I, and my children can happily tromp through fields of poison ivy and poison oak without a problem. My son was the only one out of his scout troop to come home from his 50 mile hike without a rash.

    It would be interesting to find out whether the legend has actual grounds or if we're just weirdly immune for other reasons.

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