by Karly Forker
Whether it is in a spot you can’t quite reach, or it comes right as you’re about to fall asleep, we have all experienced the annoying sensation of itching daily. Sometimes it is a slight crawling sensation, or it can be so intense it is almost painful, so what is an itch and why does it feel so good to scratch it?
Itching, or pruritus as it is known scientifically, is a common sensation caused by stimulated nerve cells in the skin. The occurrence itself is actually quite complex and is a result of communication between skin cells and the nervous system.
Though sometimes we itch due to external factors like environmental irritants, certain fabrics or textures, a very common cause of itching is dry skin. Dry skin causes small cracks of fractures in our protective skin barrier. These fractures lead to inflammation, which acts as a signal for our cells to recruit special chemicals like histamine and kinins. Histamine and kinins are chemicals that cause slight nerve irritation, among other things, and our body interprets this as an itch.
To relieve itches, we instinctively scratch, which actually inflicts minor amounts of pain. Sending small amounts of pain signals to the brain temporarily distracts the brain from the itching sensation, so we are really just masking the itch with pain. Because the pain signal can release serotonin in the brain (a feel good chemical), that is why it feels so good to scratch an itch. Unfortunately, the serotonin can also “reset” the itch, leading to the all too familiar itch-scratch cycle where you may feel you can’t stop scratching (Figure 1).
Though itching from dry skin can often be remedied by applying moisturizers, persistent itchy skin may be a reason to consult your doctor or dermatologist to ensure any factors like food allergy, medications or other skin care products are not the culprit. So, next time you scratch an itch, remember it is actually a complex interaction between chemicals in your brain and body!
Figure 1. Scratching an itch can sometimes lead to the itch-scratch cycle where scratching feels good due to the release of serotonin, but the serotonin also resets the cycle to keep you itchy. Credit Getty Images.
