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Why Paper Cuts Are the Worst Kind of Pain

(Image credit: Laurence Facun)

What do you get when you cross a human finger with a paper's edge? Try: an obscene amount of pain. Why do such little cuts hurt so much?

It turns out that fingers and paper pair perfectly to produce a potent witch's brew of pain, with each ingredient bringing something special to the mix.

First, because we use them so often for tactile testing, our fingers are coated with an extremely high concentration of nocireceptors, or nerve fibers that send touch and pain signals to the brain. This makes fingers especially sensitive our "Achilles' heels" when it comes to rifling through papers.

As for paper itself, it's the perfect battleax. Sharp-edged enough to break skin, but too blunt to make a clean cut, paper carves through fingers like a dull, jagged saw. It doesn't cut deep, but this only makes matters worse: it keeps the blade riding high, at surface level, where nocireceptors that send the sharpest type of pain signals are typically concentrated.

Even worse, shallow cuts don't bleed much, so they don't readily clot and seal. Instead they remain open, exposing nerves to the air for a protracted length of time.

They just keep on stinging.

Follow Natalie Wolchover on Twitter @nattyover. Follow Life's Little Mysteries on Twitter @llmysteries, then join us on Facebook.

Natalie Wolchover was a staff writer for Live Science from 2010 to 2012 and is currently a senior physics writer and editor for Quanta Magazine. She holds a bachelor's degree in physics from Tufts University and has studied physics at the University of California, Berkeley. Along with the staff of Quanta, Wolchover won the 2022 Pulitzer Prize for explanatory writing for her work on the building of the James Webb Space Telescope. Her work has also appeared in the The Best American Science and Nature Writing and The Best Writing on Mathematics, Nature, The New Yorker and Popular Science. She was the 2016 winner of the  Evert Clark/Seth Payne Award, an annual prize for young science journalists, as well as the winner of the 2017 Science Communication Award for the American Institute of Physics.