Foot Health Glossary

Corn

Clavus
Medically reviewed · Hottinger Podologie, ZurichUpdated: July 2026

A corn (clavus) is a punctual callus with a central core that grows inward. It forms at points of constant pressure, typically over joints, on the tops of toes, the sole or between the toes, and hurts because the core presses on nerve endings.

Plate · Corn © HOTTINGER PODOLOGIE Pressure & friction, e.g. from tight footwear Callus layer Keratin core, grows inward Nerve endings, hence the pain Epidermis Dermis Skin cross-section with keratin core
Constant pressure makes a keratin core grow inward, irritating the nerve endings of the dermis. That is why a corn hurts with pinpoint precision. · Illustration: Hottinger Podologie
Common causes
  • Tight or hard shoes, high heels
  • Toe deformities such as hammer toes or bunions
  • Bony prominences, dry skin
What you can do yourself

Remove the pressure, that is half the treatment: roomy footwear, protective rings, toe padding. Be careful with acid corn plasters: they cannot tell callus from healthy skin, and with diabetes or circulatory disorders they are off limits.

When to see a podiatrist

If it hurts, keeps returning or you are not sure it is a corn at all: plantar warts look confusingly similar but are treated differently. In the practice the core is removed precisely and usually with little pain, and the cause of the pressure is discussed with you.

Did you know?

The Latin name clavus means "nail", fittingly: the keratin core acts like a small nail pressed into the skin at every step.

Common questions
Corn or wart: how do I tell the difference?
A corn has a glassy core and hurts under direct pressure; a plantar wart often shows small dark dots (capillaries) and hurts more when squeezed from the sides. When in doubt: show it to us rather than guess.
Will the corn come back after removal?
Only if the pressure remains. That is why treatment always includes the question of footwear, foot statics and protective padding.
Related terms
Sources & further reading
Hottinger Podologie · Zurich

Concerns about your feet, skin or nails?

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Angelika WinklbauerPodiatry & medical foot care
This entry provides general information and does not replace an individual examination.