Corns and calluses are thickened areas of hardened, dead skin, caused by pressure or friction on the skin. They form to protect the skin and structures under the skin from pressure, friction, and injury. They may appear grayish or yellowish, be less sensitive to the touch than surrounding skin, and feel bumpy. Corns generally are found where toes rub together. Because of their shape, corns intensify the pressure at the tip and can cause deep tissue damage and ulceration. Hard corns are especially problematic for people with insensitive skin due to diabetes, etc.

Signs and Symptoms

Corns generally are found where toes rub together. Corns have an inner core that can be soft or hard.

• A soft corn looks like an open sore.
• A soft corn is found between toes (usually the fourth and fifth toes)
• A hard corn is also firm and thick. It may have a soft yellow ring with a gray center. A hard corn is often found over a bony part of a toe (usually the fifth toe)

Causes

Corns are caused by thickened areas of hardened, dead skin, caused by pressure or friction on the skin, often footwear:

• Tight shoes squeeze the foot.
• High‐heeled shoes squeeze the front part of the foot.
• Loose shoes may cause your foot to slide and rub against the shoe.
• Shoes with a thin sole can create more pressure on the ball of the foot when walking than do thicker‐soled shoes.
• Wearing sandals and shoes without socks can lead to increased friction.
• Tight shoes squeeze the foot.