Key facts
- Scratching an itch, while providing temporary relief, leads to increased swelling and inflammation.
- Pain-sensing nerves release substance P, which activates mast cells, a key component of the immune response.
- This activation by substance P is a different pathway than that triggered by allergens.
- Mice prevented from scratching showed significantly less swelling and fewer inflammatory cells.
- Scratching might offer a minor evolutionary benefit by helping to fend off certain skin bacteria.
- Dermatologists advise against scratching and suggest topical treatments like hydrocortisone cream or menthol-based products.
New research is shedding light on the age-old advice to avoid scratching bug bites and rashes. While scratching provides immediate relief, scientists have discovered it can worsen the itch and inflammation. Studies involving mice, some fitted with "cones of shame" to prevent scratching, revealed that the act of scratching triggers pain-sensing nerves. These nerves release a chemical messenger, substance P, which activates mast cells – immune system responders. This activation, distinct from allergen responses, leads to increased inflammation. Although scratching might offer a minor benefit in combating certain skin bacteria, researchers emphasize that the overall effect is detrimental. Dermatologists recommend alternative methods for itch relief, such as hydrocortisone cream, calamine lotion, oatmeal baths, or menthol-containing products that create a cooling sensation to distract from the itch.