Corns and Calluses
A corn is a protective layer of dead skin cells that forms due to repeated friction. It is cone-shaped and has a knobby core that points inward. This core can put pressure on a nerve and cause sharp pain. Corns can develop on the top of, or between, toes. If a corn develops between the toes, it may be kept pliable by the moisture from perspiration and is therefore called a soft corn.
Corns develop as a result of friction from the toes rubbing together or against the shoe. They often occur from the following:
- Shoes, socks, or stockings that fit too tightly around the toes
- Pressure on the toes from high-heeled shoes
- Shoes that are too loose, due to the friction of the foot sliding within the shoe
- Deformed and crooked toes
Calluses are composed of the same material as corns. Calluses, however, develop on the ball or heel of the foot. The skin on the sole of the foot is ordinarily about 40 times thicker than the skin anywhere else on the body, but a callus can even be twice as thick. A protective callus layer naturally develops to guard against excessive pressure and chafing as people get older and the padding of fat on the bottom of the foot thins out. If calluses get too big or too hard, they may pull and tear the underlying skin.
Risk factors for calluses include the following:
- Poorly fitting shoes
- Walking regularly on hard surfaces
- Flat feet
Review Date: 01/30/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.