A foot corn is a thick layer of dead skin that forms on the foot due to excess pressure or friction, notes WebMD. A corn can be hard or soft and develop on the top, sides or in between toes.
Hard corns are firm and may have a soft, yellow ring. Soft corns look like open sores, and they develop when sweat gets trapped inside of a hard corn, notes WebMD. Pressure from footwear is a common cause of foot corns, and while corns are generally not painful, they can cause pain in someone who is wearing shoes. Squeezing a foot corn can also cause pain.
Individuals with a bunion, a hammertoe or any type of foot deformity have an increased risk of developing a foot corn, since these deformities can cause excess friction inside of shoes, explains Mayo Clinic. Corns that develop due to poorly fitting shoes may go away when the right shoe size is worn. Corns can also be treated with protective pads that are placed on top of the corn to decrease friction. Doctors can use a scalpel to trim away excess skin and may recommend using a shoe insert to help reduce friction between the corn and material in the shoe.