Insect bites - why does heat treatment relieve itching?

[Stephen Tashi]

TL;DR

Why does treating an insect bite with heat relieve the itching (if it does).?

There are electrical devices that treat insect bites by heating the affected area. (e.g. https://www.amazon.com/dp/B08MT4Z89C/?tag=pfamazon01-20 ) People on a forum I trust say that they work. Why would the method work?

Do they merely deaden the nerves in the affected area?
Do they cause some other biological reaction to heat that changes the chemistry or biology of the affected area?
Was using heat treatment on insect bites a well known method before the development of these electric devices?

 

[BillTre]

I usually put ice on stings and bites if I do anything to them.
To me, this seems to reduce inflammation (localized swelling) which can lead to pain and itching.
it also should deaden the nerves.

From knowing gymnasts and footballers, I know they like to alternate heat and cold on sore muscles.
The rationale is that heat draws more blood flow to an area, flooding the location with fluids. The cold then causes blood to lead the area, removing some knid of bad chemical stuff (like damaged cellular debris from damaged muscle cells, too many ions of particular types, or other potentially problematic stuff). This is supposed to promote recovery.

Applying heat to a bite might wash away bad bite stuff in the flood of incoming new blood.

Another possibility is that the heat in some way inactivates come chemicals in the bite. This may be specific to bites of certain organisms which leave certain (heat sensitive) compounds their bites. I think I have heard of this, but don't remember details.

In general, higher temperatures may speed the healing process, but that is probably on a longer time scale.

 

[berkeman]

TL;DR Summary: Why does treating an insect bite with heat relieve the itching (if it does).?

Do they merely deaden the nerves in the affected area?
Do they cause some other biological reaction to heat that changes the chemistry or biology of the affected area?
Was using heat treatment on insect bites a well known method before the development of these electric devices?

Here's a link to medical information about using heat as a treatment for insect bites:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257884/

 

[Laroxe]

I'd never come across these before, so was inspired to check them out, as Berkeman suggests there is some evidence that they can help and there is a folk belief about using hot spoons, it's not clear why they should work, but there are some theories. One suggests the heat disrupts some of the inflammatory proteins, but this seems unlikely, the heat from a 3-6 second application wouldn't go far and the effect on a range of bites and stings suggest a number of different biochemical pathways. You would need to apply the heat immediately after the bite, as the inflammatory proteins are releases almost immediately. Using temperature to alter blood flow might have some effect, and cold is commonly used as well as heat.

I did notice that some people comment that the sensation of heat is as painful as the bite, this makes the idea of the heat acting as a counter irritant altering the nerve conduction of pain, more credible, capsicum creams use the same principle. In this case, the nerve isn't deadened, our nerves use a variety of ways to sense and transmit pain signals, they also appear to prioritise some sensations as more dangerous, heat for example, this happens before any processing in the brain. Counter irritants can overstimulate some nerve receptors and modify the sensory route, but really the most effective are used over an area rather than a specific point. Unfortunately, all studies on pain are plagued by subjectivity, attention/context, memory and various other placebo influences. Along with these issues, many people describe alterations in the inflammatory responses, which these ideas couldn't adequately explain.

It's interesting, but the effectiveness seems very variable, and some people describe the sensation as worse than the original bite, currently I'm not really tempted to dash out and buy one, insect repellant works, well most of the time anyway. I suspect that if immunologists were convinced the initial inflammation could be controlled, there would be an interest in testing this as a way to prevent some anaphylactic reactions, in fact the only comments by an immunologist I found about these devices were lukewarm at best.

 

[Bystander]

It's interesting, but the effectiveness seems very variable, and some people describe the sensation as worse than the original bite, currently I'm not really tempted to dash out and buy one, insect repellant works, well most of the time anyway. I suspect that if immunologists were convinced the initial inflammation could be controlled, there would be an interes

"Cure worse than disease?" Indomethicin (sp?) for my gout...until I learned of my "allergy" to black licorice/anise, and various flavorings present in A&W (maybe Dad's), was regularly in ER for treatment/prescription; digestive agony takes the mind off piddling little joint inflammations. An "occasional" root beer/piece of licorice...no pigging out these days....

 

[JT Smith]

I've found that a hot shower provides temporary relief from the itching of poison oak. I'm not the only one to have noticed this. It seems to help with insect bites as well, for a little while. Supposedly the heat causes an increase in blood flow and hence a reduction of inflammation. Well, at least that's what I read on the internet.

 

[Bystander]

https://www.google.com/search?q=red...jBqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8#ip=1

Traditional black licorice flavor comes from a chemical called glycyrrhizin, which is 50 times sweeter than cane sugar. "It's quite potent-smelling," Newton-Cheh said. And it can do much more than add flavor.

Gave up and "Googled;" TIL plus https://www.physicsforums.com/threads/example-of-debate-on-artificial-sweeteners.1052202/.

 

[DaveC426913]

My technique works amazingly (for me).

Put the bite under running water as hot as you can stand for 20-30 seconds.
Immediately switch the water to freezing cold for 20-30 seconds. (It's got to be running water.)
Repeat this cycle a couple of times depending on the severity of the bite.

This completely relieves all sensation from a bite for an hour to several hours (say, long enough to get some sleep).

 

[lata chaudhary]

Insect bites often trigger an immune response, leading to the release of histamine and other inflammatory substances. These substances can cause itching and discomfort. Applying heat to the affected area can denature or break down these proteins, reducing the inflammatory response and alleviating itching.

 

[DaveC426913]

Applying heat to the affected area can denature or break down these proteins

This is the idea at least. The questions then become:

How hot does it need to be to denature the proteins?
How long does it need to applied?
How soon does it need to be applied before the proteins have diffused too far?

 

[Rive]

TL;DR Summary: Why does treating an insect bite with heat relieve the itching (if it does).?

People on a forum I trust say that they work. Why would the method work?

As I recall there was a mention somewhere (sorry, I could not google up the name of the effect) that self-inflicted pain (may be other stimuli too) feels less intense/inconvenient than unintended one and helps to divert attention from real inconveniences: primarily pain (wounds) was mentioned, but I think it would work for itch too.

 

[JT Smith]

Who says heat is painful? A hot shower feels good to me whether I'm itchy or not.

 

[DaveC426913]

Who says heat is painful? A hot shower feels good to me whether I'm itchy or not.

Me. My experience is that if its not on the verge of pain, its not really enough to relieve the itch for very long at all. But I'm talking spot heat, not all over heat.

And you want to follow it up with numbing cold. Even ice cubes aren't enough of a heat sink.

 

[JT Smith]

Then I guess the question is complicated by the fact that people are different and sources of itching are different. In my case it doesn't require painfully hot water. And the other people who I've talked to about this say the same thing.

If it's pain and not heat then you could just slap the itchy skin repeatedly. Does that work for you?

 

[Hornbein]

I once saw someone treat their bites with a spark generating device. Surely the idea was to zap the nerve in order to inhibit it. It seems that any overpowering stimulus works.

Whenever I've managed to relieve a chronic pain a lesser pain it was masking emerges. Presumably there is some end to this.

 

[JT Smith]

Whenever I've managed to relieve a chronic pain a lesser pain it was masking emerges. Presumably there is some end to this.

Death.

 

[jim mcnamara]

Autophagy = the equivalent, in intracellular terms, of taking out the garbage.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960406/ -- this explains the effect of localized heat to increase the rate of autophagy.

Alternating heat/cold starts the autophagy process with a "heat on signal", then switches it off to "allow for garbage pick up" -- immune responses that remove the debris from dead/damaged cells.

This is why sprains often elicit a suggestion:
heat for x minutes,
then cold for x minutes:
where x is short period of time that providers specify based on their clinical experience. Plus this is simple to do at home.

 

[Laroxe]

Autophagy = the equivalent, in intracellular terms, of taking out the garbage.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960406/ -- this explains the effect of localized heat to increase the rate of autophagy.

Alternating heat/cold starts the autophagy process with a "heat on signal", then switches it off to "allow for garbage pick up" -- immune responses that remove the debris from dead/damaged cells.

This is why sprains often elicit a suggestion:
heat for x minutes,
then cold for x minutes:
where x is short period of time that providers specify based on their clinical experience. Plus this is simple to do at home.

Usually the first aid advice for sprains or local injuries is to apply cold compresses as the swelling is often the result of bleeding and the vasoconstriction from cold help stop this, along with rest, compression and elevation. Heat is recommended after the first 24 hours and this causes vasodilation and increased permeability of the blood vessels. I'd never really considered the effects on the phagocytes, but yes, they do become activated to clean up the damaged tissue. I'm not sure about the alternating temperatures, though I suspect this might be about pain relief.
The problem is that a lot of the ideas don't really match up to the very local treatment of stings etc, these are area effects. I also think that the vasodilation would actually increase inflammation and tissue enzymes become more active when warmed, good for healing but not for acute inflammatory reactions.
I know that with some types of pain, particularly nerve pain some people find cold helpful and heat worsens it, with other people the reveres is true, so for the same local stimulus we seem to get quite different responses. It makes me think we might be missing something in the way we understand pain, it might help explain why research is so difficult.