Scratching that itch? Science confirms it only makes rashes worse

We’ve all experienced it – rashes that appear out of nowhere, tempting us into scratching for momentary relief. We listen to our parents’ cautions but give in anyway, only to have the itch return, worse than ever.

Now, a study has confirmed what many of us have long suspected: scratching doesn’t just fail to help – it actually makes things worse, exacerbating inflammation and prolonging healing.

The research sheds light on why the itch-scratch cycle is so tough to break. Surprisingly, while scratching feels satisfying in the moment, scientists say it actually has an evolutionary purpose that’s more complex than just relief.

Rashes and the urge to scratch

The research was focused on a type of eczema known as allergic contact dermatitis. This condition is caused by an allergic reaction to various allergens or skin irritants – including poison ivy and certain metals like nickel – and prompts an itchy, swollen rash.

Giving in to the urge to scratch only fuels the fire – increasing inflammation, exacerbating symptoms, and hindering the healing process.

Study lead author Daniel Kaplan is a professor of dermatology and immunology at the University of Pittsburgh.

“At first, these findings seemed to introduce a paradox: If scratching an itch is bad for us, why does it feel so good? Scratching is often pleasurable, which suggests that, in order to have evolved, this behavior must provide some kind of benefit,” noted Kaplan.

“Our study helps resolve this paradox by providing evidence that scratching also provides defense against bacterial skin infections.”

The scratch-itch cycle in rashes

To investigate what perpetuates the scratch-itch cycle in rashes, the researchers used itch-inducing allergens to simulate eczema-like symptoms on the ears of two groups of mice. One group was normal, while the other lacked an itch-sensing neuron (and was unable to feel itchy).

The researchers found that the ears of the mice that could scratch were significantly more swollen and filled with inflammatory immune cells called neutrophils compared to the group that couldn’t scratch.

This experiment validated the notion that scratching indeed worsens the skin condition. The researchers discovered that scratching precipitates the release of a compound called substance P by pain-sensing neurons.

This substance then triggers the activation of mast cells, immune cells that play a pivotal role in driving itchiness and inflammation through the recruitment of neutrophils.

“In contact dermatitis, mast cells are directly activated by allergens, which drives minor inflammation and itchiness,” explained Professor Kaplan.

“In response to scratching, the release of substance P activates mast cells through a second pathway, so the reason that scratching triggers more inflammation in the skin is because mast cells have been synergistically activated through two pathways.”

Scratching rashes and skin defense

While mast cells can intensify existing skin irritations, they also aid in the protection against bacteria and other pathogens.

The research team decided to explore whether the activation of mast cells induced by scratching could influence the skin’s microbiome.

The findings revealed that scratching lessened the presence of Staphylococcus aureus, a common bacteria involved in skin infections, on the skin.

“The finding that scratching improves defense against Staphylococcus aureus suggests that it could be beneficial in some contexts,” said Kaplan. “But the damage that scratching does to the skin probably outweighs this benefit when itching is chronic.”

Future research directions

Researchers at the University of Pittsburgh plan to develop new therapies for dermatitis, rosacea, and urticaria. They aim to reduce inflammation by targeting specific receptors on mast cells. These immune cells play a key role in triggering itchiness and swelling.

By understanding how scratching worsens inflammation, scientists hope to create treatments that break the itch-scratch cycle. Their findings could lead to better options for people suffering from chronic skin conditions.

The research highlights why avoiding scratching is essential for healthier skin. Scratching may feel good in the moment, but it often makes rashes worse by increasing inflammation. While it can help fight bacteria, the long-term damage outweighs the short-term relief.

Next time your skin itches, think twice before scratching. Instead, try soothing lotions, cool compresses, or medications to reduce irritation. Sometimes, resisting the urge can help your skin heal faster and prevent further discomfort.

The full study was published in the journal Science.

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