Kaplan Team Links Scratching to Worse Rashes via 2nd Mast-Cell Pathway
Updated
Updated · The Associated Press · Jun 27
Kaplan Team Links Scratching to Worse Rashes via 2nd Mast-Cell Pathway
2 articles · Updated · The Associated Press · Jun 27
Summary
Mouse experiments showed itchy rashes swelled more when animals could scratch, while mice blocked by tiny collars developed less inflammation and fewer immune cells.
Substance P—released by pain-sensing nerves when scratching starts to hurt—activated mast cells through a second pathway beyond allergens, helping explain why bites and rashes get itchier and more inflamed.
The same work suggests a limited upside: scratched, bacteria-infected mouse ears carried lower levels of Staphylococcus aureus, possibly because added inflammation boosted germ defense.
Kaplan said that benefit does not outweigh the harm, noting an ignored mosquito bite often fades in 5 to 10 minutes but can linger for a week if scratched.
The findings point to possible new treatments, including experimental MRGPRX2 blockers, while current advice remains hydrocortisone, calamine, oatmeal baths or menthol creams to break the itch-scratch cycle.