I recently read that mangos contain urushiol, the substance in poison ivy that causes the rash. I wonder if slowing increasing the amount of mangos would help develop a tolerance for the chemical. Thoughts?

Many believe that people become more sensitive to urishiol over time, increasing incrementally with further episodes of contact. Perhaps this is strictly dermatologically speaking, but one cannot be too careful about flawed scientific assumptions. Can you think of a similar organic chemical substance that we develop immunities for in such a manner?

I have heard of people that were insensitive to Poison Oak, had one serious contact episode like breathing Poison Oak fire smoke, then were very sensitive.

But that's different than what you're saying - slow low exposure

My wife was dehydrating mangos last night and I told her that some people are allergic to it, something she had not heard before. So when I looked it up I found it contains urushiol. I wasn't looking for an antidote for poison ivy. I remember reading somewhere that repeated exposure to urushiol to the skin has the opposite effect, you become more intolerant to it. I have also heard that some people eat small doses of poison ivy to gain immunity -- probably a folk myth and potentially dangerous.

The urushiol in mangos is concentrated mainly in the skin, from what I heard, but no matter how well I skin them I get a rash around my mouth a few days after eating them unless I wash my face right after eating fresh mango.

The whole process of allergy shots is giving small doses and building up incrementally over time, but I'm not sure it works the same taking the antigen orally.

For the majority of my life I was not allergic to poison ivy, My brother on an occasion pushed me down a hill of poison ivy with no shirt or shoes on. I was 100% fine. Now I can get it. Albeit very mildly only a few bumps and does not spread much.

A friend of mine said that every time he gets it now it is worse and worse each time. Rather then the exposure to the oil building up a tolerance it is doing the opposite and each time he gets it it is more severe and longer lasting.

That could be what happened to me as well, I have a naturally high resistance to reaction but over the years after repeat exposure I have begun to show symptoms.

Best action against poison ivy, oak or sumac is to was the contacted part of the body within 30 minutes. Each exposure to the chemical makes you more sensitive. Jewelweed is found along our Bruce Trail, often where poison ivy grows nearby. This plant's gooey interior is the only antidote I know of for poison ivy. Mangoes are probably as effective as bananas are for mosquitoes... in other words - not very.

And... I used to pull poison ivy out of our driveway with my bare hands - never had a reaction (probably because I am OCD about washing my hands). Then on my first fateful backpacking trip... I had some stomach issues due to pre-packaged backpacking fare that contained ingredients that don't sit well with me... so I apparently when I sat my pants on the log that was covered in dormant vines... it must have been poison ivy. I had the blisters from my ankle to the cheeks. Not pleasant... frankly I am surprised I ever went out again after that trip.

Edited by Laurie_Ann on 02/08/2012 09:42:00 MST.

Here in Portland all the landscapers I know carry Technu skin cleanser. It is a lifesaver if you contact poison ivy , oak or deadly nightshade.Over the years my reactions to deadly nightshade get worse with each exposure. I think it is a type of auto-immune response.

I'm screamingly allergic to poison oak (and also to English Ivy) and have studied this a bit a talked to docs and dermatologists about it.

Laurie's right, washing with water removes the urushiol from the SURFACE of your skin. The sooner the better and I've had good luck washing every 10 minutes when I've had to contact poison oak. At times, I've traveled with prednisone and I'm ready to do 60mg/day till you see improvement and then 50mg, 40mg, 30mg, 20mg, 10mg on successive days. If you get a really bad case, I was impressed how very quickly the reaction settled down with injected steroids. Like every 4 hours I was feeling 50% more human. I thought it would take more time for just the physical injuries - broken skin from severe rashes and swelling, etc - to heal, but 12 hours later it looked like maybe I'd just done dishes in hot water with harsh detergent.

But I haven't had any more than a few spots for 30 years since I got good at IDing poison oak. I have had bad contact dermatitis from English Ivy until I learned I was allergic to it. So I'm a big fan of getting REALLY good at IDing the plant in all seasons and in all its forms (creeping ivy, bush, groundcover, leafless plant, leaf litter, sticks on the ground). A certain curve to a bare stick and I swerve around it and avoid exposure that way.

I concur with everyone else's experience on repeated exposures. I know many people who have become more sensitive over time. I don't know anyone who has really lessened their sensitivity although I've met people who had an urban-legend-like belief in low-dose-exposures building immunity or drinking milk from poison-oak-eating-goats, etc. Offer to rub some poison oak on those "immune" individuals and they refuse. Vaccines (and even just being around other people) help us avoid infectious diseases by INCREASING our immune reaction. Contact dermatitis is already TOO MUCH immune reaction, I don't want my body to have more immune reaction to those compounds.

Nick: Thanks for the heads-up on mango. I hadn't known that, I'll be more careful with them around the house as food and while hiking in Hawaii in March - apparently the leaves are worse than the fruit. Checking that out, I also found that cashews and pistachios have some, but it is deactivated in roasting the nuts.

It doesn't contain urushiol, but I learned only a few years that cow parsnip is in the celery family and has much more of a photo-sensitizing chemical than celery does. Farm and grocery workers can react to celery but cow parsnip contains so much more of the chemical that it is easier to react. I got a second-degree sunburn in a day (at sea level on a cloudy day) from cow parsnip exposure. A 1" blister on the back of my hand that I first thought was a chemical burn (from what I didn't know) but the margins were actually tanned. So I did some research. And now I (1) cover up before going through big stands of it, (2) try to avoid breaking the leaves or stem and getting the sap on me (the biggest risk) and (3) hike some trails early in the season before they are so overgrown.

David, we should fix you up with a nice dried flower arrangement, poison oak and Devil's Club.

--B.G.--

When I was younger I was very sensitive to poison oak, to the point of being hospitalized. Nowadays I only seem to get very small breakouts if I don't wash up within 2 hours or so.

I don't really know if I am more tolerant or just more aware of my contact with the plant.

My dermatologist who treated me frequently when I was young, told me that everyone is allergic to urushiol, what varies is how long it has to be in contact before you have an allergic reaction.

Dawn dish detergent is all I use to wash up.

I should know better than to admit this but...

I used to be horribly sensitive to poison ivy ever since a childhood mishap involving some vines, that resulted in much embarrassment and a one month course of corticosteroids. Unfortunately, I encounter a lot of poison ivy in the course of hiking and foraging. In fact, my favorite spot for picking fiddleheads by a nearby river is a virtual obstacle course of poison ivy. A few years ago, I came across a paragraph in a book by reknowed foragers Euell Gibbons, who described the following method:

Each spring, as soon as the new poison ivy leaves emerge, eat a small cluster of three leaves. Continue to do this daily, picking larger and larger leaves each day, until you finally graduate to full sized leaves.

Euell wisely cautioned readers not to try this, but went on to state that it had allowed him to develop complete immunity to poison ivy.

I am not averse to a little risk taking in the name of science, so I decided to try it about 5 years ago. The first time my wife saw me pluck and eat some, she thought I had lost it.Surprisingly, nothing bad happened, so I continued to faithfully follow this practice. I've done so every spring since then for the past 5 years. I now don't bat an eye when I find myself walking through ivy, and I seem fairly resistant.

In the words of my mentor, I'd strongly caution against trying this. If you are foolish enough to do so, please wash before handling your privates...

I have some corrections to the posts about poison ivy/poison oak. At the end I will give my credentials. I got my info from many clinical studies, not from internet posts or articles, because the same wrong info is circulating around and around, and not being corrected or updated.

The allergenic oil in mangos is resorcinol. The allergenic oil in poison ivy/oak, including poison sumac, is urushiol. They are together in the botanical family, but not genus.

There is enough of a similarity between the two oils (although urushiol is considered to be stronger) that if you are allergic to one, you are allergic to the other. It follows that if you develop a tolerance to one, you develop a tolerance to the other, although you may not respond to mango exposure but get a reaction from PI/PO if it is a strong exposure.

Native Hawaiians usually have no reaction to mangos, but tourists do. This is from lifelong exposure. The skin is regarded as being the problem more than leaves, because the fruit is eaten a lot. The resin canals (the allergenic oil is in the resin) are in the skin, and when broken the resin leaks out. The oil can also migrate into the pulp that normally would not contain the oil. The highly allergic can get a reaction from even mango juice because of this leakage.

Most folks have a threshold. Pass that with exposure, and you are allergic. More exposure can increase the allergy, but certain amounts of small exposure consistently has been shown to sometimes cause a buildup of tolerance within the immune system.
All this is very complicated, not easily thrown out in a few words.

Two studies on jewelweed have not shown any benefit, but easterners often swear by it.

Yes, Technu works to remove the allergenic oil, but contains a somewhat toxic petrochemical, but it is smart to carry something for immediate oil removal. If you dont have anything, dig down to the real soil under mulch immediately after exposure and scrub the dry clay on exposed skin. Clay pulls oil to itself. Straight water does not cut oil. You need a strong soap, alcohol, etc. Carry bentonite clay with you. It's works better than dirt clay.

That "certain curve"in a bare winter branch is the plants reach upward toward the sun as it grows toward open paths. Good for you in noticing that. People develop a automatic poison ivy/oak sensor over time. Certain growth and botanical patterns are very distinctive.

Cashews have allergenic oils, cardol and anacardiol which are in the shell of the nut. The oil of the nut itself is harmless. Imported cashews are shelled first, but sometimes the oil gets on the nuts. They are all heated a bit, because this makes the oil harmless. All cashews have been heated, even though they may be called raw. The same as with mango oil—if you are allergic to poison ivy/oak, you are probably allergic to cashew oil.

My credentials: I wrote "The Poison Oak & Poison Ivy Survival Guide."

Thanks for your informative input Sandra.
I am exposed to poison oak on a regular basis ( some months daily, others weekly but not a month without ..)and I have noticed that every two years or so, I will get an extreme reaction, to where I need cortisone shots and steroids, and after that I am almost ok for a few months, even though I continue to be around it and work it in. Then I start getting it more and more until the big reaction again and then I can rest easier for a while. Like I said, my exposure is very regular and I don't think that it has too much to do with being more careful after a bad case..
Does this make any sense to you?
Thanks!

When someone is extremely allergic, it can be really hard to get a tolerance. I would get head to toe cases after I moved to the hills of Santa Cruz CA I noticed through the next 4 years that even though I always had an itch somewhere on my body, the cases became less and less serious. I have continued to live in PO ( in southern OR), and now I need to dab a drop of the resin on my inner wrist to get a tiny bump. So my tolerance, from continual exposure, progressed nicely to almost complete tolerance since 1970 when it was the worst.

That being said, the problem with this allergy is that it is so different for everybody. It is up and down, depending upon whether the cells that can stop or prevent the reaction are built up enough.

Oral Ivy is a homeopathic formula that had clinical studies that verified it was effective (even so, as I said, each person is different).
It is advertised to take in the early spring for seasonal tolerance, but many people take it all year. Maybe a consistent dose would help smooth things out. You need a buildup of specialized T cells (the regulatory system) to dampen the fire, or prevent a flare up in the first place, and consistency in exposure to keep these cells built up.

Thanks for that Sandra. Good information and I stand corrected about the Jewelweed.

By the way, a plant we are having issues with up here is Giant Hogweed and I think I'd rather run into poison ivy than that.

Dont give up on jewelweed Laurie. This was not a clinical study, but James Duke, an herbalist, during his workshops, said he would rub the inside of both wrists with poison ivy leaves. A minute or two later, he would wipe one wrist with a ball of crushed jewelweed leaves and stems. Three days later, the wrist rubbed with jewelweed would have a minor eruption or none at all, while the untended wrist would be itchy with a rash.
The studies I mentioned were dealing with stopping the itch. This technique was to stop the rash from forming. I would still try to clean the oil off, and then if there was some jewelweed near by, I would do this also.