What’s Actually Underneath Your Fingernails?

In this edition of It’s Not a Stupid Question, we find out what the skin underneath our nails is really like, and why messing with it is so painful.

What’s Actually Underneath Your Fingernails?

The area underneath our fingernails is like the deepest depths of the ocean: It is, for most of us, uncharted territory. What’s really going on underneath those thin keratin shields? Is the skin any different to that on the rest of our body? Dermatologist Anthony Rossi and primary care physician Marc Leavey helped us get to the bottom of our questions.

First, the actual skin underneath our fingernails really isn’t all that different from the skin elsewhere on the body aside from the fact that it adheres to the bottom of the nail, and is chock-full of nerves to provide our hands with the extra sensation they need to perform day-to-day tasks. “For the most part, this skin is very sensitive because of the abundance of nerve endings we need there in order to help us with touch,” Rossi explains.

While this is useful most of the time, it also means it’s agony if something gets rammed in there. That’s not the only reason it’s so painful, though—it also has to do with an abundance of pressure. “Classically, if we hit our finger with a hammer, it bleeds underneath the nail,” Leavey explains. “Then, that blood expands into this encapsulated place where there’s really no room for anything to expand.” The result? Tense, throbbing pain. The best way to relieve this pressure is to somehow create an opening in the nail itself—something that can be achieved, as Leavey says, with a red-hot paper clip (two things here: Firstly, we do not endorse trying this technique at home, and secondly, do not watch the below video if you find the sight of a literal fountain of blood upsetting).

 While the skin below the nails isn’t anything out of the ordinary, the bacteria that makes a home down there certainly is. According to one study, while other areas of the hand house hundreds (sometimes thousands) of bacteria, the area underneath our fingernails yields hundreds of thousands of bacteria per fingertip. According to researchers, this happens because the space between the skin and the nail provides both the physical protection and moisture necessary to create the perfect environment for bacterial growth. The space is also near impervious to our best means of killing germssoap.

With the above in mind, do your best to clean the parts you can reach—especially if you’re one of the 23 percent of men who admit to trimming their nails by biting them. You really don’t want that bacterial orgy moving from your fingernails to your mouth.