The researchers also demonstrated that scratching prompts pain-sensing neurons to release a chemical known as substance P, which triggers mast cells: cells involved in the immune system, causing inflammation and itchiness via neutrophils.

Mice that were free to scratch their itchy ears saw the number of immune cells go up and levels of infection-causing bacteria decline

Scratching is something most of us do mindlessly. It doesn’t have to be a big deal, unless it is in hard to reach place. But it can also become a nuisance when you keep itching and end up hurting yourself,