WHY DO WE… ITCH?

US Dermatologist Andrew Liu wondered why we find scratching quite so irresistible, even though it can damage our skin. In tests, he discovered that scratching activates nerves and mast cells – a key part of the immune system – creating a loop that makes the skin itchier. He also found a surprising benefit to this process. Scratching also boosts immune responses against skin bacteria. In mice with infections, itching followed by scratching helped fight off Staphylococcus aureus. This bacterium can cause skin conditions such as boils and impetigo. 

Of course, that immune activation bonus doesn’t compensate for the damage caused by clawing at skin that’s already damaged by chronic conditions, such as eczema. Now, scientists hope that understanding more about the biological mechanisms that drive our need to scratch that itch will help them find ways to tame the sensation.