Paper cuts are usually small and relatively superficial. But why do they hurt so much?
The generally accepted reason why paper cuts hurt so much is that you usually get them on fingers and hands, where your skin is packed with an extremely high concentration of nerve fibers called nociceptors – sensory receptors that trigger the sensation of pain in response to potentially damaging stimulus. There are more nociceptors per square millimeter in your hands and fingers than most of the rest of your body. That is why cuts on your hands and fingers are significantly more painful than cuts on the other part of your body.
What these receptors actually do is that when your skin is exposed to high temperature, harsh chemicals and any pressure (that they think will break the skin), they trigger a cascade of electrical and chemical signals to the brain informing about injury. Then your brain, in turn, makes you aware of injury with the experience of pain. The nose and the groin area have a similar concentration of nociceptors. So you will experience the same amount of pain in those areas as you will on fingers and hands when you get papercut.
Moreover, a paper cut is not quite as clean as it looks. The edges of paper may seem perfectly smooth. But on a microscopic level, they are very dull and flexible. When a thin piece of paper cuts through skin, it is more like a saw than a knife, meaning it does a lot more microscopic damage to the skin compared to knife cut that leaves a relatively clean cut. Also, paper leaves behind chemical-coated particles which irritate the wound.
Even more terrifying, since paper cuts are generally shallow, they don’t bleed or clot very much. But what makes paper cuts hurt more but bleed less?
The epidermis, the outermost cellular layer of the skin, is only about as thin as a piece of paper. And the dermis, a layer below the epidermis, is where the nerve fibers (nociceptors) are. Since the epidermis is quite thin, a paper cut can easily reach the dermis and get right into those nerve endings, yet not deep enough to get to the blood vessels – causing all that pain but a little, or no bleeding at all.
Seriously, a paper cut shouldn’t be a big deal. I know it hurts like hell but what I mean is you don’t need any sort of medical attention. There has been no report of infection resulting from it so far, too. Fingertips and hands are where you usually get a paper cut; you probably pay more attention to it because it’s on body parts you use so often.