Health Topics A-Z

What Is A Corn? What Is a Callus?

They can be annoying, but your body actually forms them to protect sensitive skin. They affect about 5% of the population. Corns and calluses are often confused with one another. Corns generally occur on parts of the feet that don't bear weight like on the tops and sides of the toes and also on the balls of the feet. Calluses can develop on hands, feet, or anywhere there is repeated friction — even on a violinist's chin.

A hard corn is a small patch of thickened, dead skin with a packed center. A soft corn has a much thinner surface and usually occurs between 4th and 5th toes. A seed corn, the least common type, is a patch of stiff skin around a tiny plug of cholesterol. Seed corns occur only on the bottom of the feet, often because of a condition caused by lack of perspiration.

Like corns, calluses have several variants. The common callus usually occurs when there's been a lot of rubbing against the hands or feet. The plantar callus is found on the bottom of the foot. The hereditary callus is found on the soles or palms. All are larger than corns — up to an inch in diameter — and lack the corn's telltale center.

What Causes Them?

Some corns and calluses on the feet develop from improper walking motion, but most are caused by ill-fitting shoes. High-heeled shoes are the worst offenders. They put pressure on the toes and make women four times as likely as men to have foot problems. Other risk factors for developing a corn or callus include foot deformities and wearing shoes/sandals without socks which leads to friction on the feet.

Either rubbing or pressure can cause soft corns and plantar calluses. If your child develops a callus that has no clear source of pressure, it is probably a genetically determined hereditary callus. Feet spend most of their time in a closed, moist environment ideal for breeding bacteria. Staph infections can start when bacteria enter corns through breaks in the skin and cause the infected corn to give off fluid or pus.