Does Scratching that Itch Provide Any Benefits? A New Study Says Yes and No

The urge to scratch bug bites, rashes, and other skin irritations can be overwhelming. However, new research reveals why resisting the temptation may be beneficial.

Biologically, scratching presents a paradox. It provides a sense of relief, suggesting it might have an evolutionary advantage. However, as many have experienced, scratching mosquito bites or rashes often worsens the irritation. It can even damage the skin, increasing the risk of infection.

Scientists at the University of Pittsburgh aimed to resolve this paradox—investigating whether scratching is truly as harmful as it seems while also exploring any potential benefits.

To do so, they exposed mice to itch-inducing allergens, triggering eczema-like symptoms on their ears. The mice were divided into three groups: one had the freedom to scratch, another was genetically altered to lack itch-sensing neurons in the affected area, and the third wore Elizabethan collars (often called “cones of shame” in dogs) to prevent scratching.

As expected, the mice that scratched experienced worse symptoms than the other groups. However, the study also revealed why.

Activation of Pain-Sensing Neurons and Inflammatory Response

Researchers found that scratching activated pain-sensing neurons, which then released a peptide called “substance P.” This, in turn, triggered mast cells—immune cells distributed throughout the body. When activated, these mast cells initiated an inflammatory response by recruiting neutrophils, a type of white blood cell involved in immune defense.

In essence, this chain reaction of chemicals and immune cells explains why scratching an itch often leads to increased irritation and inflammation.

“In cases of contact dermatitis, allergens directly activate mast cells, leading to mild inflammation and itching,” explained senior study author Daniel Kaplan. “However, scratching introduces a second pathway by triggering the release of substance P, which further stimulates mast cells. This dual activation is why scratching exacerbates inflammation in the skin.”

Since mast cells play a role in innate immunity, researchers questioned whether their activation through scratching might offer some protection against infections.

Impact of Scratching on Skin Bacteria

Their findings confirmed that scratching did, in fact, lower levels of Staphylococcus aureus on the skin. This bacterium, known for causing staph infections, is one of the most common culprits behind skin infections.

However, the researchers believe that this potential benefit does not outweigh the harm scratching causes to the affected area.

“The fact that scratching helps defend against Staphylococcus aureus suggests it may have some advantages in certain situations,” said Kaplan. “But when itching becomes chronic, the skin damage caused by scratching likely outweighs any benefit.”

Or, to put it simply—just like your mom always said: “Stop scratching!”

These findings have motivated the research team to further investigate mast cells, particularly how targeting their receptors could lead to new treatments for inflammatory skin conditions like rosacea.

Read the original article on: New Atlas

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