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How the Itch Informs the Scratch

Research finds that where the itch begins says a lot about how bad it is--and how pleasurable the scratch. Christie Nicholson reports














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Itch. Past studies have shown that whatever the cause—perhaps just hearing me talk about itch—something triggers nerve fibers that send a signal lighting up three areas of the brain: the emotional regions; the limbic system that sparks the urge to scratch; and the cortex that tells you where to scratch.

And recently researchers discovered that where the itch begins can predict how bad it is—and how much pleasure you’ll get by scratching it. The study is in the British Journal of Dermatology.  

The researchers induced an itch on the ankles, forearms and backs of 18 subjects. And the research team also relieved the itch in a uniform way with a scratching device, rather than let each subject go to town in different and unmeasureable ways.

The results: The experimentally induced itch was particularly bad on the back and ankle. And scratching the back got rid of the itch most effectively. But scratching the ankle provided the most pleasurable relief.

So not all itches are created equal, even if they’re induced equally. The next steps are to find out why, and whether there is a treatment that can match the pleasure of the scratch.

—Christie Nicholson

[The above text is a transcript of this podcast.]  


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  1. 1. DaveInAustinTx 07:32 PM 1/28/12

    I thought that itching was the same physical sensation as pain in the epidermis but at too low a threshold for subcutaneous nerves to detect as pain (similar to the way pressure or tickling is felt). If so, is that sensation transmitted to the nerve fibers through the epidermis? Would that also explain why a small cut may not be painful when it occurs but itches while healing?

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  2. 2. Lowndes 09:07 PM 1/28/12

    I've had an allergic reaction to something since 1966, looked like a very bad case of poison ivy, only worse. It itched much worse than poison ivy. I found that the pain of a burn or cut was much, much easier to bear than prolonged, severe itching. Severe itching is agony. I can actually ignore poison ivy itching now. But what I also discovered was that a very light "tickling" (VERY lightly stroking the area with fingertips) will totally mask, or hide, or replace the itching sensation, but only while you are doing it. I also found that cooling the area with ice helped somewhat.

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  3. 3. MikeN in reply to Lowndes 09:58 PM 1/28/12

    Hello Lowndes:

    I had a severe itch for about five years (scratched right through the bleeding). About a year ago I discovered a cream called "Betametasona Clotrimazol Gentamicina". This STOPS THE ITCH !

    Definitely the best anti-itch cream I've ever used. If you need information, please let me know.

    Have a good day ...

    Mike

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  4. 4. jtdwyer 09:11 AM 1/29/12

    Having had really dry skin for decades now, especially in the forearms, ankles and legs) (which might have been a result of repeated soaking with jet fuel in Viet Nam), I suggest that the the peripheral appendages may be more prone to dehydration than the trunk. I really get it from the close proximity ankle height heater vents in most cars.

    BTW, there's no longer any hair on my old ankles, even though I almost never resort to scratching and seldom wear socks - I suspect it simply breaks off...

    If peripheral appendages are more likely to be exposed to severe skin damage and less likely to receive hydrating blood circulation, these factors could help explain the differences in the intensity of itching sensations and the perception of relief produced by scratching.

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  5. 5. jtdwyer in reply to MikeN 09:24 AM 1/29/12

    Sounds interesting, but some may depend on what ails you. From what I could find, some people could have serious side effects, especially with Gentamicin...

    http://en.wikipedia.org/wiki/Betamethasone
    "Betamethasone is a potent glucocorticoid steroid with anti-inflammatory and immunosuppressive properties. Unlike other drugs with these effects, betamethasone does not cause water retention. It is applied as a topical cream, ointment, foam, lotion or gel to treat itching."
    "Betamethasone is available in a number of compound forms: betamethasone dipropionate (branded as Diprosone, Diprolene, Celestamine, and others), sodium phosphate (branded as Bentelan in Italy) and valerate (branded as Betnovate, Celestone and others). In the United States and Canada, betamethasone is mixed with clotrimazole and sold as Lotrisone and Lotriderm."

    http://en.wikipedia.org/wiki/Clotrimazole
    "Clotrimazole (brand name Canesten or Lotrimin) is an antifungal medication commonly used in the treatment of fungal infections (of both humans and other animals) such as vaginal yeast infections, oral thrush, and ringworm. It is also used to treat athlete's foot and jock itch."

    http://en.wikipedia.org/wiki/Gentamicin
    "Gentamicin is an aminoglycoside antibiotic, used to treat many types of bacterial infections, particularly those caused by Gram-negative organisms."

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  6. 6. Lowndes 11:01 AM 1/29/12

    JTDwyer,

    I have the same dry, itchy skin and hairless ankles you describe, but I never got dosed with jet fuel. But, THANK YOU for your service, and WELCOME HOME.
    My remedy is lukewarm showers (the skin's natural oils are easily washed off by hot water) and baby oil rubbed in while still wet in the shower. Other types of oil work well, too, olive oil and almond oil work for me. Baby oil is a mineral oil, sometimes with an aloe additive. There is no odor after a few minutes, but with the relief, I wouldn't care. About a teaspoon full on each arm and leg, rubbed in, not just "on". Be careful, it can make the tub very slippery.

    Hope this helps!!

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  7. 7. Bops in reply to DaveInAustinTx 07:47 PM 1/29/12

    Recently, I read that it's now two different nerve signals, from
    Wikipedia.




    .






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  8. 8. abrasileirosilva 08:20 PM 1/29/12

    In Brazil we have a popular saying: It is as itching from Bahia (one Brazilian state), the more we scratch ourselves the more we desire scratching (and more harm is caused to us). In Portuguese: Isso é como coceira bahiana, quanto mais coca mais dana (a coçar e a nos causar danos).
    Not ask me from what situation or how this proverb was born; I do not know!

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  9. 9. Bops 08:35 PM 1/29/12

    I had an itchy allergic skin problem for two years.
    Nothing helped, the biopsies, three different times, came back allergic skin reaction.

    Now, I have been looking everything up from foods, chemicals, plastics. bugs, fibers, cloths.

    One of the causes may be my favorite food garlic.
    And...Mangoes have urushiol, the chemical in poison ivy and poison sumac. It's worst if you eat it. It's not on the package!

    Anything bitter tasting is mostly likely a bit toxic and can make you very itchy. You have to look these foods up they are all somewhat different. I love fluff, but it's very bitter if you taste it slowly.
    Could be the corn syrup.

    The most surprising was that burning, like hot peppers, is an allergic reaction. Hot can cause may other upsets not just itching.
    Really taste the food you eat slowly, if you suspect anything look them up. Wikipedia is my first start, the information is very helpful.

    Not just wool can be itchy, polyester voc's big time...carpets and cloths and the list goes on.

    Some people are very allergic to concrete. Sweeping or washing, I would have NEVER EVER thought that to cause itchy dermatitis.
    It's the lime stone, most times.

    Itching is a very complicated problem, I've lost track of the hours and hours I have spent reading.

    I helped four people so far stop itching. They were just lucky.
    Me, and the cat, we both still take benadryl.


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  10. 10. abrasileirosilva in reply to abrasileirosilva 08:35 PM 1/29/12

    In Portuguese: Isso e(h)como coceira bahiana, quanto mais coça *cosa* mais dana (a coçar *cosar* e a nos causar danos).

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  11. 11. Bops 10:24 PM 1/29/12

    These 3 helped me the most.
    Still don't know for sure what caused all this itching.
    I also took predisone, cypro, and other stuff but, it really did not help much.

    Diprolene helped the skin rash in small spots.
    Neosproin with pain under a band-aid, helped me not scratch holes in my skin.
    Benadryl and Aspirin or Tylenol worked ok.

    The doctor suggested and I found these to helpful too.
    Eating foods with olive oil, salads, one daily vitamin, one Omega 3 fish oil, D3 2,000 units, (low levels will cause itchy skin by itself).
    Nuts, sunflower seeds, butter, peanut butter.

    Hibiclens helped prevent skin infections, works good and is gentle on the skin.
    Not sure about other soaps, still reading about chemicals and dermatitides.
    I use very small amounts of non-scented clear liquid, Ivory free and clear. Good for hands if you use contact lens. No bar soap because it leaves a white dirty film that has fungus and Bactria galore. No moisture soaps, they collect, make the shower greasy, and bacteria loves oil. (Found out most toxins like to stick to oil too. All the things you learn on the way to fixing itchy skin.) and No colors, it stains the grout. Our water dept says that oil and grease are the hardest to get out of the drinking water. I like to protect our drinking water and to have the shower fungus free and clean. I'm an X-OR Tech.

    I like Vaseline the best. Just before leaving the shower, a small amount mixed with warm water on your hand. Neosporin is very good too, small amount mixed with warm water. Doctor gave me Men-Phor, anti-itch lotion, it worked for poison ivy. Not much works great for very itchy rashes. Never eat mangoes if you get poison ivy.

    Common sense and time works.
    Baking soda, oatmeal...messy, didn't notice any improvement.
    Salt's good to draw infections out and helps the pain.
    Works wonders for our fish and tank.

    Sometimes, hair just falls out. Eyebrows are a good example.
    Sometimes they land on your chin and grow. Just kidding.

    Hope I said something that will be useful.
    Thank you for helping to keep us free.
    My dad said, We have to stand up to bullies.








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  12. 12. Bops in reply to jtdwyer 10:33 PM 1/29/12

    These three things helped itchy skin the most is a reply to maybe help you.
    Sorry, forgot to click your reply spot.

    Thanks for the information about the creams.

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  13. 13. dmoffittsmith 05:27 PM 2/1/12

    What is it about almost scalding water that soooo much satisfies itches like poison ivy? It's hard to stop increasing H2O temp while your doing it, but it stops the itch for hours.

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