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Comment by LeoPanthera | Hacker News Reader

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.

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As others have said, it depends on the cause of the itch.

I have an alpha-galactose allergy. This is sort of a food allergy: beef and lamb, probably venison and to a lesser extent pork, trigger it. But unlike other food allergies, this doesn't hit me at the time, but maybe six or eight hours later. While I can get hives whenever I eat too much of that kind of meat (which of course I try to avoid), the best guarantee that it will happen after such a meal is heat on my skin. Initially, this happened several times when I stopped running after an hour or so, and my body was no longer cooled by the breeze and by breathing hard; but I've also gotten hives when taking a hot shower hours after eating beef, or sleeping under more blankets than I really need.

BTW, the alpha-gal allergy is transmitted by bites of the Lone Star Tick. You don't get hives from the bite, but it somehow makes you allergic to beef. And I'm not making this up--it is well documented: https://www.mayoclinic.org/diseases-conditions/alpha-gal-syn...; see also https://en.wikipedia.org/wiki/Exercise-induced_anaphylaxis on the link between exercise and hives.

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!

Hear is going to open the skin pores and relax veins/arteries, so it could be problematic for such things.

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.)

For mosquito bites, I thought hot water was recommended and effective?

https://pmc.ncbi.nlm.nih.gov/articles/PMC10309056/ supports this.

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.

It's effective, yes.

But when you have more than a few bites, you probably will not want to do that. Even more if you feel them a lot, and if you are not used to have lots of mosquito bites on you.

Yep, for mozzie bites there are pens that have a hot tip that you press on the itch. I think the heat breaks down the stuff (protein?) that is causing the itch.

For large swaths of dry skin, I've found that dragging a (retired) credit card across the skin works incredibly well.

It's rough enough to scratch the itch, but gentle enough to not break the skin.

I've done it with an active credit card and it does the trick, too.

Yeah but the fees are outrageous.

I bought a loofah pad and it works amazingly well. Never breaks the skin.

> as hot as you can possibly stand without burning

Hm, this is the same way to treat stingray wounds. Something something bloodflow vasodialator?

My understanding about hot water is that it causes localized histamine release, which then depletes the available histamine to trigger the itch reflex.

Certainly works great for poison oak and eczema, regardless of the actual mechanism.

Many sea-animal toxins are protein based, and heat will denature the protein making it harmless. Similarly, acid (like vinegar) can help, e.g. for jellyfish stings.

(And if the toxin has penetrated your skin by e.g. the sharp tail of a stingray, heat will be better than vinegar since you can't get the vinegar "inside" your body... whereas jellyfish toxin tends to sit on the surface of your skin)

There are penlike devices that apply heat and remove the itch as well. propably safer and more accessible that hot water.

Afterbite. Its mostly acid and other caustic stuff to clean the area and kill off any nerve endings immediately inside the bite wound. It works. Just don't itch too much before applying. Afterbite on a scratched bite hurts like acid on a wound ... which it is.

https://afterbite.com/

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