Why Do Your Fingers Wrinkle in Water? It Is Not Swelling
After a long bath or swim, your fingertips turn into raisins. The usual explanation turns out to be wrong.
Not swelling
A Binghamton University news story explains that received wisdom held that water swells the skin and makes fingers wrinkly, but little research had tested that. Professor Guy German and his team found that blood vessels beneath the skin contract after prolonged immersion, and that is where the wrinkles come from.
An active process
A 2013 paper in Biology Letters notes that wrinkle formation on the hands and feet is an active process controlled by the autonomic nervous system. Binghamton adds a side finding: German says wrinkles do not form in fingers with median nerve damage, which one of his students with that condition confirmed when tested.
The same wrinkles every time
In a 2025 study reported by Binghamton, subjects put their fingers in water for 30 minutes and were photographed, then repeated the test at least 24 hours later. German and Rachel Laytin found the same patterns of raised loops and ridges both times. German says blood vessels do not move much relative to each other, so the wrinkles form the same way.
Why might we do it?
The 2013 Biology Letters study found that people handled submerged objects more quickly with wrinkled fingers than with unwrinkled ones, while wrinkles made no difference with dry objects. The authors say this supports the idea that wrinkles may be an adaptation for handling objects in wet conditions. That is a hypothesis the results support, not a settled fact.
Sources
- Binghamton University, Research shows fingers wrinkle the same way with every water immersion (May 7, 2025): https://www.binghamton.edu/news/story/5547/do-your-fingers-wrinkle-the-same-way-every-time-youre-in-the-water-too-long-new-research-says-yes
- Kareklas K, Nettle D, Smulders TV, Water-induced finger wrinkles improve handling of wet objects, Biology Letters (April 23, 2013): https://royalsocietypublishing.org/rsbl/article/9/2/20120999/49308/Water-induced-finger-wrinkles-improve-handling-of
Facts checked: October 12, 2026.