Why scratching that itch can give health benefits - but also be bad for you

If scratching an itch feels so good, why do scientists say it’s so bad?

Existing research suggests scratching itchy skin can often make it worse, aggravating a wound and spreading harmful bacteria.

However, a new study has fleshed out this paradox, offering a good reason to go ahead and scratch that pesky itch. In a study with mice, researchers from the University of Pittsburgh found that scratching our skin could protect us from some infections.

By inducing eczema-like symptoms on mice’s ears, the research team looked into the difference between mice who were allowed to scratch their itchy skin and those wearing a collar stopping them from scratching.

The ears of the mice allowed to scratch swelled up more and were found to contain a type of white blood cell, called neutrophils, which help our body fight infection. The team also found that scratching worsens inflammation, therefore fuelling an “itch-scratch cycle” that could explain why scratching an itch feels good, but makes us scratch more.

“There's this really vicious itch-scratch cycle that can't be broken,” says immunologist Aaron Ver Heul at Washington University School of Medicine in St. Louis, in Missouri, who wasn’t involved in the research. “Identifying a circuit like this hopefully will lead to therapeutics that will be better at breaking the cycle.”

Surprisingly, however, the team found that scratching has antibacterial properties. Mice that were allowed to scratch had much lower levels of a potentially dangerous type of bacteria than those who couldn’t scratch themselves.

“At first, these findings seemed to introduce a paradox: If scratching an itch is bad for us, why does it feel so good?” said senior author Daniel Kaplan, professor of dermatology and of