You know the feeling. You’re sitting there in perfect comfort and contentment when, all of a sudden, the worst itch you could possibly imagine comes out of nowhere and leaves you squirming for relief.
Before you even have time to think about it, your reflexes kick in, and you start scratching away at the offending patch of skin. You know scratching feels good, but do you know why?
That squirmy-itchy feeling you get is caused by signals sent to your brain by tiny nerve endings. Scientists believe about 5% of our nerves are wired to send these itch signals, which are received by the same part of the brain that controls our pain response reflexes. When we scratch, we cause ourselves minor pain, causing the brain to flood the area with pain-reducing chemicals that override the itch. For most incidental itches, this response is long enough.
Researchers suspect everyday itches actually evolved as a way to induce soft-skinned animals — including humans — to scratch. So, what’s the benefit to scratching? When we scratch, we scrape off dead skin cells, allowing new skin to come to the surface. In this way, our skin regenerates itself, and remains healthy and protective.
But there’s another kind of itch you’re probably familiar with. When we’re exposed to an allergen — such as poison ivy or the venom in a mosquito’s stinger — our bodies fight off the infection with a chemical called histamine. Because it causes our blood vessels to swell up around potentially harmful foreign substances that enter the body, histamine can makes us feel itchy.
As with other kinds of itches, scratching an itch caused by histamine can also feel good, but only temporarily. These types of itches are more long-lived than the other kind of itch, which makes people more likely to scratch them until the skin breaks. That’s why it’s not usually a good idea to scratch bites, rashes, and other kinds of long-term itches. Instead, an inexpensive over-the-counter antihistamine cream will usually do the trick.
If scratching doesn’t work, check out some natural itch cures.