Why Do Fingers Get Wrinkly in the Bath?

KohakuHave you ever noticed your fingers getting wrinkly after a long bath?

The answer in 30 seconds

It isn't because your skin soaks up water. It is a reaction controlled by the autonomic nervous system, which makes the small blood vessels in your fingertips narrow.

The wrinkles are not from soaking up water. The autonomic nervous system makes tiny blood vessels in your fingertips narrow, which reduces fingertip volume and pulls the skin into ridges. In an experiment, people picked up wet objects about 12% faster with wrinkled fingers, so the wrinkles may work like tire treads for a better grip.

Not from sopping up water

The skin on your fingers and toes can wrinkle after a long soak in a bath or pool. People once thought the skin simply soaked up water and swelled. But we now know that nerves make the small blood vessels in your fingertips narrow. This reduces the fingertip volume and pulls the skin into the wrinkly pattern.

Nerves and blood vessels

This process is controlled by the autonomic nervous system, which handles body functions you don't control, like your heartbeat and blood vessels. Because of this, finger wrinkles have been used in medical settings as a clue about how well the autonomic nerves are working.

Figure: Wrinkles channel water away like tire treads

KohakuSome researchers think the wrinkles work like tire treads and help you grip wet objects.

A grip like tire treads

Why would fingers wrinkle? A leading idea is that wrinkles help you grip wet objects. A thin layer of water between your finger and an object can make things slippery. Wrinkles may channel water away, like the treads on a car tire, giving you a better grip.

Tested with wet objects

In a 2013 experiment, 20 people moved objects underwater with wrinkled and unwrinkled fingers. They were about 12% faster with wrinkled fingers, but there was no difference for dry objects. This supports the idea that wrinkles are useful in water. The wrinkles usually go away on their own after you dry off.

Want to know more?

In the same experiment, people took about 17% longer to move underwater objects than dry ones.
To make the wrinkles in the study, participants soaked their hands in 40°C water for 30 minutes. The wrinkles took 10-20 minutes to fade.
Your skin is coated with an oil called sebum that makes it a bit waterproof. A long soak washes some sebum away, but the wrinkling itself is not caused by water soaking in.

KohakuThe wrinkles fade on their own once you are out of the water, so there is no need to worry. It may simply be your body's clever way of handling wet things.

Quick quiz: test yourself

What directly makes fingers wrinkle in the bath?

Show the answer

Nerves make the blood vessels shrink
The skin soaks up water and swells
The finger bones get shorter

Nerves make the blood vessels shrink People once thought the skin soaked up water and swelled, but we now know the autonomic nervous system makes the fingertip blood vessels narrow, which pulls the skin into wrinkles.

Sources

Water-induced finger wrinkles improve handling of wet objectsBiology Letters（PMC 掲載の査読論文）
Why Does My Skin Get Wrinkly in Water? (for Kids)Nemours KidsHealth

This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.