Why Does Scratching Make An Itch Worse?
Have you ever wondered why scratching an itch can make it feel MORE itchy, not less? A group of researchers has been looking into this phenomenon, and has recently found that a brain feedback loop may be partly responsible for it.
The scientists, from Washington University in St. Louis, found that when you scratch an itch your brain releases a bit of serotonin to control the pain. But the serotonin can move from the brain to the spinal cord, where it intensifies the itchy sensations instead of controlling the pain.
Lead author Zhou-Feng Chen summed the finding up by saying, “We always have wondered why this vicious itch-pain cycle occurs. Our findings suggest that the events happen in this order. First, you scratch, and that causes a sensation of pain. Then you make more serotonin to control the pain. But serotonin does more than only inhibit pain. Our new finding shows that it also makes itch worse by activating GRPR neurons through 5HT1A receptors.”
To learn more, you can read this in-depth article.