Scratching releases serotonin, making you itch more

Scratch that itch, and you won’t ditch it. Instead, it will get worse, thanks to a chemical messenger called serotonin.

Scratching spurs the brain to release serotonin, best known for its role in regulating mood, to control the pain sensations felt on the skin. The serotonin flows from the brain to the spinal cord, where it can jump from pain-sensing nerve cells to neurons linked to itching and make the itch sensation worse, researchers report October 30 in Neuron. The team has also identified a pathway that links serotonin to increased itchiness, which could be a future target to stop the itch-scratch-itch cycle.