Eli5: why does scratching a bug bite feel so good?

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Eli5: why does scratching a bug bite feel so good?

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Definitely not an expert, but from what I understand it’s an allergic reaction to a numbing chemical bugs put in you when they bite you. That’s why we usually don’t feel it until it’s too late, and it swells up and gets itchy.

Bug bites suck.
There are various types from things like venom or physical bites that are different, but let’s take the mosquito.

Small needle thing sucking blood, but to be more effective it does things like inject saliva while taking out blood. This saliva acts as a local blood thinner.

The body does not like this. So after the bite it swells up and has a mild allergic reaction to it.
Cells rush in and fight the foreign material inside the bite. That itches.

So now you itch. Which also sucks.
But scratching is a new controlled sensation. Mild “pain” of scratching is a new sensation that is less annoying than itching. The mild “pain” signal “drowns out” the itchy signal.

Same way things like local menthol rubs feel cool and can distract against soreness.

Bonus round: scratching too much can also damage the bug bite. This leads to more irritation and more itching.

I think it’s the release of histamines which makes it feel good, but in turn, make the bug bite more inflammed

^ this, also dirt and bacteria on your fingers or nails can infect the bite, leading to more protection cells being released. This inflames the area more, releasing more histamines. Always scratch in a circle around the bite.

I believe that evolution has programmed us to find scratching pleasurable (at least temporarily). The itch indicates something is wrong on your skin. Your body says “scratch that thing” in order to shoo away the bug or whatever might be causing it. Also to tell you to avoid that situation in the future.

Try this experiment: next time you have an itch, do not scratch directly on it. Scratch near it and around it and you will experience less positive “feedback” from your skin/brain. Your body will respond by increasing the itch sensation in the actual spot. Then when you do hit the spot, your reward seems to be greater. You will also experience this when you have someone else scratch your back. It becomes more frustrating as they fail to locate the exact spot of your itching. Evolution is amazing!