It is a well-known fact that scratching blocks the itching sensation. The pain that is accompanied by scratching manages to temporarily distract the brain from the itch. These pain signals are transmitted to the brain by nerve cells just like an itchy feeling is also transmitted by another set of nerve cells.
http://www.medicaldaily.com/scratching-itchy-skin-causes-brain-release-hormone-serotonin-intensifies-itchy-sensation-308458
It's because pain also travels through a crude pathway, and through experience we learned that by activating touch pathways, we overwhelm the crude pain pathways, and it more or less reduces the amount of pain we experience. 1  permalink. 2  embed. 3  save. give gold.
https://www.reddit.com/r/explainlikeimfive/comments/1md53w/why_does_scratching_a_bug_bite_feel_so_good/
Scratching Itchy Skin Causes Brain To Release Hormone Serotonin, Intensifies Itchy Sensation. While a good scratch may temporarily relieve you of your itch, it actually stimulates serotonin in the brain that intensifies the itchy feeling.
http://www.medicaldaily.com/scratching-itchy-skin-causes-brain-release-hormone-serotonin-intensifies-itchy-sensation-308458
Itching, or pruritus, can be caused by a variety of different things, from irritation to skin conditions such as eczema. Even some cancers and chemotherapies can cause chronic itching, a condition which is far from an annoyance; it seriously affects quality of life.
http://www.iflscience.com/health-and-medicine/why-does-scratching-itch-make-it-worse/
It’s the unpleasant feeling that makes us instinctively scratch and scratch and scratch. So why does a fingernail almost instantly make an itch feel better? J R Traver began to itch around her 40th birthday, and would continue to scratch away at her skin until her death some 40 years later.
http://www.bbc.com/future/story/20160226-why-its-feels-so-good-to-scratch-an-itch
“Scratching can relieve itch by creating minor pain. But when the body responds to pain signals, that response actually can make itching worse.”. Chen goes on to explain that while serotonin helps alleviate pain in the brain, it also eventually spreads to the spinal cord.
http://www.iflscience.com/health-and-medicine/why-does-scratching-itch-make-it-worse/
If you scratch, then the sensation that provoked it is by definition an itch. It’s a definition that may be reliable, but it’s probably not all that useful. At first glance, itch and pain seem to be related.
http://www.bbc.com/future/story/20160226-why-its-feels-so-good-to-scratch-an-itch
Of course, a bunch of scientists have, and they think they’ve cracked it. After investigating itching in mice, researchers from Washington University in St. Louis found that scratching causes the brain to release your “happy hormone” serotonin, which actually makes the itch worse.
http://www.iflscience.com/health-and-medicine/why-does-scratching-itch-make-it-worse/
TLDR: There are two types of sensations, fine and crude. Pain is an example of a crude sensation and touch is an example of a fine sensation. Both crude and fine sensory pathways are activated together, and when they are, the fine sensations generally overwhelm the crude sensations. That's why when you feel pain, touching it makes it feel better.
https://www.reddit.com/r/explainlikeimfive/comments/1md53w/why_does_scratching_a_bug_bite_feel_so_good/
Giving a good scratch to an itch is probably the most satisfying sensation one can feel, but according to a new study from Washington University School of Medicine in St. Louis, nothing is worse than scratching, since it causes the brain to release serotonin, which intensifies the itch sensation.
http://www.medicaldaily.com/scratching-itchy-skin-causes-brain-release-hormone-serotonin-intensifies-itchy-sensation-308458
why do itches feel good after
An itch is probably the most satisfying sensation which one can feel.