Why Scratching Makes Us Even More Itchy

A look at why our brains tell us to keep scratching.

Video of Why Scratching Makes Us Even More Itchy

Marsha Lewis, Contributing Producer

(Inside Science TV) -- Why do we itch?

"That’s a really tough question," said Brian Kim, a dermatologist at the Center for the Study of Itch located at Washington University School of Medicine in St. Louis, Missouri.

Science supports what mom has said all along: The more you scratch, the more you itch. And the more you itch, the more you scratch.

"When you evoke the pain sensation, you try to suppress the itch sensation," said Zhou-Fen Chen, a developmental biologist at the center.

The researchers at the center found the pain of scratching and the sensation of itching go hand in hand -- creating an irritating cycle.

A new study in mice showed scratching causes the brain to release serotonin, and that serotonin intensifies the itch sensation, so they scratch. Then the brain releases more serotonin, making them feel even itchier. Researchers think this same pattern happens in humans -- and worst of all, sometimes all you have to do is think about it.

"It's likely just the thought of itching is one way by which your central nervous system triggers the sensation of itch," Kim said.

The Center for the Study of Itch is the first of its kind in the U.S. Its goal is to understand and develop better treatments for serious itching conditions and to learn more about how the skin, nerves and immune systems work together.

"The one thing we do know? It's almost impossible to not scratch if you're itching," said Kim.