Frequrently when I have an insect bite or rash accompanied by fairly intense itching, I find that I can get relief by subjecting the area to hot water from a faucet or shower – as hot and as long as I can stand it without actually scalding it. This usually seems to work better than commercial anti-itch creams.
Can anyone explain why the hot water treatment works?
I used that method to curb the itching from poison ivy on my feet and also some itching from my hands. The scalding would keep the itch away for about three hours.
I don’t know why it works although somebody pointed out that scalding, like scratching, is just another way of creating localize pain where the itch occurs and that its the pain induction that overloads the itching. This is just hearsay so I don’t think I’ve helped answer the question.
I’ve always heard that it essentially exhausts the supply of the chemicals in the nerves that send the itching signals to your brain. The pain from the heat and the itch use the same neural pathways, and by overloading them, wearing them out, you get a few hours of relief until the body can replenish the needed chemicals.
Here is my sketchy memory from my neuroscience days: pain, itching, and extreme temperature (both hot and cold) are all relayed along the same nerve pathway. This pathway has a feedback loop at the sensory end, which will “turn off” the nerve if the sensation becomes too intense. So, if you run water that is so hot it triggers the “pain-itch” pathway instead of the “heat” pathway, you may eventually overload the pain-itch pathway and shut it down.
Notice that really, really hot water becomes indistinguishable from really, really cold water? Because they both get shuffled into the pain pathway.
Also, because the pain-itch pathway is after all a sensory nerve in your skin, it is susceptible to other kinds of stimulation if they are strong enough… it is not designed to respond to pressure or vibration, but if they are intense enough, it will. This is why rubbing and scratching can also help pain and itching.
Hot water is An absolute fantastic treatment for poison ivy. As embarrassing as it may be I have actually had an orgasm while running hot water on my poison ivy infected arms. And no I haven’t intentionally infected myself with poison ivy to replicate the tx. (although the thought has crossed my mind! 
And just like that, I’m subscribed to this thread.
An explanation that I heard is that it uses up all of the histamines, which is what makes you itch, in the skin which then take around 10 hours to regenerate.
Hot water works wonders except I haven’t found it to be effective on chigger bites which is a completely different thing than poison ivy itch - Stylostome - Wikipedia
Just ramp the heat up hotter and hotter, as hot as you can stand it and the itch will fairly scream but when you’re done, no itch at all.
Wow! Hot zombie itch!
I am not seeing any linkage between the histamine explanation, nor the nerve pathways explanation, and post #5, the mysterious orgasm. In the normal course of events, why would pain or itch cause that reaction?
I’ve read that hot water ultimately worsens itchiness caused by dry skin in the winter, as it drives off the oils in the skin.
Well, that’s not what this thread is about. Dry-skin itching has nothing to do with insect-bite or poison-ivy itching.
Oops, it’s right there in the OP. Guess I’m the one who needs coffee.
I haven’t had an orgasm, but by far the most intensely pleasurable non-sexual experience I’ve ever had was when I had really bad poison oak over my entire torso. Each morning, I’d wake up super-itchy, get the shower nice and hot, and then step in. The hot water over that much skin at the same time was a pretty overwhelming sensory experience.
Have you considered trying to replicate the effect of the tx without the presence of poison ivy?
That’s why we should have a rule that newbies don’t get to zombify a thread unless they tell us what they were doing that led to opening the thread.
When I was vacationing in Oahu and staying at a beach house, the house’s guest instructions included what to do in case of jellyfish stings: run piping hot water over the stung area for several minutes. I was skeptical, because that sounded like it would just fan the fires of pain, but now I’m convinced. I did see a baby Portuguese man-of-war in the surf there, too. I’ll remember this tip for future stays.
Nitpick (from a graduate of Costanza College of Marine Biology): a baby man-of-war is called a boy-of-war.
On topic: hot water also helps my horribly itchy legs (seasonal, so probably an allergic reaction to some pollen in the air). But mine is a function of sweating.
My dad and sister have this, too. It’s only the legs, and only when they get wet. So taking a shower triggers a half hour of intense itching (and swearing and, well, yeah, some crying). But, if I work out so that I’m sweating before I shower, I’m fine. Or if I take a long, hot shower until the itching stops.
This thread has been great for the Hot Water After part of the equation. But does anyone have a clue as to why sweating before would help?