5 ms·

Is there a benefit to scratching that itch? Yes and no, says new study

44 points by zfg 2y ago

ctrlp 2y ago
Lab Mouse is officially the worst job in the world.
ryandvm 2y ago
tl;dr Scratching an itchy spot boosts the local inflammation and immune response. I know people hate the "just so" stories, but from an evolutionary perspective it makes sense. You get a parasite, it itches, you scratch it, which removes the parasite and kicks up the local immune response.
- andrewflnr 2y ago
  > which removes the parasite This is probably one of the big evolutionary factors they didn't mention. Scratching at mosquito bites after the mosquito is already gone might just be an unfortunate side effect.
the_arun 2y ago
I always thought the dry skin causes the itch (when I don't see any bug bites). So scratching would relieve us from dry skin. But, I learned something today.
- rob74 2y ago
  Yes, (very) dry skin can also itch. In that case I would suggest moisturizing cream, scratching definitely won't make it go away...
pharrington 2y ago
We already knew that scratching causes an inflammatory response. Where the specific mechanisms involved that the study found previously unknown? (editted to reword my question)
Gravityloss 2y ago
Hmm but this was an allergen, where having more white blood cells at the site isn't beneficiary. If it was bacteria or a parasite, then the story might be very different.
- nickburns 2y ago
  TFA: "That being said, because mast cells are also involved in innate immunity, the researchers wondered if scratching's role in activating them conveys some kind of infection-fighting benefit. Sure enough, they found that scratching did in fact reduce the amount of Staphylococcus aureus on the skin. S. aureus is the most common bacteria involved in skin infections and is most famously responsible for staph infections. Still, in the research team's opinion, the reduction in this bacteria from scratching doesn't outweigh the way in which the behavior worsens the area around an itch."
  - nitwit005 2y ago
    Which doesn't address what the parent comment is about. They didn't infect them with parasites, or any number of other issues that cause an itching sensation.
    - andrewflnr 2y ago
      It addressed most of the comment. Most directly, the "bacteria or..." part. And I'm sure the immune response to a parasite isn't exactly the same, but it's not hard to extrapolate that the same principle of increased immune activity being beneficial applies in that case as well.
  - SamBam 2y ago
    > in the research team's opinion This statement is carrying a lot of weight, and isn't properly justified. The authors say the reason the skin gets so inflamed is the presence of all the immune cells. They then go on to say that the immune cells seem to kill potentially harmful bacteria in the area. What is the reason they say that the body's response is problematic? It sounds a bit like saying that the fact that our upper arms become sore after an vaccination (also immune-response related) outweighs the benefits that having vaccination has.
deleted 2y ago
[deleted]
Izkata 2y ago
Ages ago I started trying to scratch itches through some fabric, like a shirt sleeve or something, so I wouldn't damage the skin (keep the fabric stationary on the itchy skin and drag your hand across the fabric). For some reason it's almost as satisfying as scratching directly, so I wonder if it gets the benefit without the downside here.
- exe34 2y ago
  I've found that gentle rubbing/massage has the same effect, although I need to remember it. also scratching through clothes hasn't always stopped me from drawing blood.
  - taeric 2y ago
    This is what I recall being taught as a kid with bad allergies and various skin conditions. Rubbing can be helpful. If so, consider rinsing with water to make sure you don't have any residual thing there upsetting your skin. Scratching through fabric is difficult because, if it does work, it could also trap the irritant in the fabric.
- eastbound 2y ago
  I just press my nail into it, to avoid scratching but to still cause the counter-itching effect.
sambeau 2y ago
(in mice)
LeoPanthera 2y ago
For persistent itches, a most effective remedy I've found is to pour hot water on it. Not burning - but as hot as you can possibly stand without burning. The hotter the better. It is only briefly painful, but it kills itches completely. I don't know why it works, but it definitely does work.
- tithe 2y ago
  Just be careful if you believe the itch is the result of something you might be allergic to (e.g., food, or bug bites). I had several bites from fire ants and ran them under hot water from the bath, which seemed to trigger (or accelerate) a full-body reaction (anaphylaxis?) and a harrowing trip to the emergency room!
  - copperx 2y ago
    Hear is going to open the skin pores and relax veins/arteries, so it could be problematic for such things.
  - marcosdumay 2y ago
    Ouch. Don't use heat to combat the symptoms of the bite of any venomous animal or any other one that secrets stuff into your body (mites, mosquitoes, etc). It's hard to tell people to do things that reduce their blood flow, because it comes with complex side effects; but definitively not do anything that increases your blood flow. (As in, if you are feeling sick, do not eat peppers either.)
    - tgsovlerkhgsel 2y ago
      For mosquito bites, I thought hot water was recommended and effective? https://pmc.ncbi.nlm.nih.gov/articles/PMC10309056/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10309056/ supports this.
      - sandworm101 2y ago
        Because virtually nobody is allergic to mosquito bites. Accelerating the blood flow/metabolism of someone maybe at risk for anaphylaxis (bee allergy) is extremely dangerous.
PaulHoule 2y ago
... but it hurts so good!
tines 2y ago
I always figured it was just to increase blood flow. That's the reason that hot water also satisfies the itch, it increases blood flow as well.
allears 2y ago
This article was about itching due to bug bites or skin disease. In my case, my back sometimes develops several itchy spots as I undress for bed. I use a back scratcher, not too heavily, the itches seem satisfied, and don't return. There's no skin damage that I'm aware of. I find it hard to believe that this is somehow harmful.
chilmers 2y ago
I have eczema, and I feel like most people who don’t have it cannot understand the experience of giving in to the urge to scratch affected skin after a period of trying to resist it. The best way I can describe it is an orgasm, the length and intensity of which you can directly control. It really is that intense. Why would we have evolved to have such an extreme pleasure response to something negative? And yet the effect of scratching on the skin seems very clearly negative. As a sufferer, it’s psychologically very difficult and confusing.

44 points by zfg 2y ago

Lab Mouse is officially the worst job in the world.

tl;dr Scratching an itchy spot boosts the local inflammation and immune response. I know people hate the "just so" stories, but from an evolutionary perspective it makes sense. You get a parasite, it itches, you scratch it, which removes the parasite and kicks up the local immune response.

andrewflnr 2y ago
> which removes the parasite This is probably one of the big evolutionary factors they didn't mention. Scratching at mosquito bites after the mosquito is already gone might just be an unfortunate side effect.

the_arun 2y ago

I always thought the dry skin causes the itch (when I don't see any bug bites). So scratching would relieve us from dry skin. But, I learned something today.

rob74 2y ago
Yes, (very) dry skin can also itch. In that case I would suggest moisturizing cream, scratching definitely won't make it go away...

pharrington 2y ago

We already knew that scratching causes an inflammatory response. Where the specific mechanisms involved that the study found previously unknown? (editted to reword my question)

Gravityloss 2y ago

Hmm but this was an allergen, where having more white blood cells at the site isn't beneficiary. If it was bacteria or a parasite, then the story might be very different.

nickburns 2y ago
TFA: "That being said, because mast cells are also involved in innate immunity, the researchers wondered if scratching's role in activating them conveys some kind of infection-fighting benefit. Sure enough, they found that scratching did in fact reduce the amount of Staphylococcus aureus on the skin. S. aureus is the most common bacteria involved in skin infections and is most famously responsible for staph infections. Still, in the research team's opinion, the reduction in this bacteria from scratching doesn't outweigh the way in which the behavior worsens the area around an itch."
- nitwit005 2y ago
  Which doesn't address what the parent comment is about. They didn't infect them with parasites, or any number of other issues that cause an itching sensation.
  - andrewflnr 2y ago
    It addressed most of the comment. Most directly, the "bacteria or..." part. And I'm sure the immune response to a parasite isn't exactly the same, but it's not hard to extrapolate that the same principle of increased immune activity being beneficial applies in that case as well.
- SamBam 2y ago
  > in the research team's opinion This statement is carrying a lot of weight, and isn't properly justified. The authors say the reason the skin gets so inflamed is the presence of all the immune cells. They then go on to say that the immune cells seem to kill potentially harmful bacteria in the area. What is the reason they say that the body's response is problematic? It sounds a bit like saying that the fact that our upper arms become sore after an vaccination (also immune-response related) outweighs the benefits that having vaccination has.

deleted 2y ago

[deleted]

Izkata 2y ago

Ages ago I started trying to scratch itches through some fabric, like a shirt sleeve or something, so I wouldn't damage the skin (keep the fabric stationary on the itchy skin and drag your hand across the fabric). For some reason it's almost as satisfying as scratching directly, so I wonder if it gets the benefit without the downside here.

exe34 2y ago
I've found that gentle rubbing/massage has the same effect, although I need to remember it. also scratching through clothes hasn't always stopped me from drawing blood.
- taeric 2y ago
  This is what I recall being taught as a kid with bad allergies and various skin conditions. Rubbing can be helpful. If so, consider rinsing with water to make sure you don't have any residual thing there upsetting your skin. Scratching through fabric is difficult because, if it does work, it could also trap the irritant in the fabric.
eastbound 2y ago
I just press my nail into it, to avoid scratching but to still cause the counter-itching effect.

sambeau 2y ago

(in mice)

LeoPanthera 2y ago

For persistent itches, a most effective remedy I've found is to pour hot water on it. Not burning - but as hot as you can possibly stand without burning. The hotter the better. It is only briefly painful, but it kills itches completely. I don't know why it works, but it definitely does work.

tithe 2y ago
Just be careful if you believe the itch is the result of something you might be allergic to (e.g., food, or bug bites). I had several bites from fire ants and ran them under hot water from the bath, which seemed to trigger (or accelerate) a full-body reaction (anaphylaxis?) and a harrowing trip to the emergency room!
- copperx 2y ago
  Hear is going to open the skin pores and relax veins/arteries, so it could be problematic for such things.
- marcosdumay 2y ago
  Ouch. Don't use heat to combat the symptoms of the bite of any venomous animal or any other one that secrets stuff into your body (mites, mosquitoes, etc). It's hard to tell people to do things that reduce their blood flow, because it comes with complex side effects; but definitively not do anything that increases your blood flow. (As in, if you are feeling sick, do not eat peppers either.)
  - tgsovlerkhgsel 2y ago
    For mosquito bites, I thought hot water was recommended and effective? https://pmc.ncbi.nlm.nih.gov/articles/PMC10309056/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10309056/ supports this.
    - sandworm101 2y ago
      Because virtually nobody is allergic to mosquito bites. Accelerating the blood flow/metabolism of someone maybe at risk for anaphylaxis (bee allergy) is extremely dangerous.

PaulHoule 2y ago

... but it hurts so good!

tines 2y ago

I always figured it was just to increase blood flow. That's the reason that hot water also satisfies the itch, it increases blood flow as well.

allears 2y ago

This article was about itching due to bug bites or skin disease. In my case, my back sometimes develops several itchy spots as I undress for bed. I use a back scratcher, not too heavily, the itches seem satisfied, and don't return. There's no skin damage that I'm aware of. I find it hard to believe that this is somehow harmful.

chilmers 2y ago

I have eczema, and I feel like most people who don’t have it cannot understand the experience of giving in to the urge to scratch affected skin after a period of trying to resist it. The best way I can describe it is an orgasm, the length and intensity of which you can directly control. It really is that intense. Why would we have evolved to have such an extreme pleasure response to something negative? And yet the effect of scratching on the skin seems very clearly negative. As a sufferer, it’s psychologically very difficult and confusing.