Most foot warts are harmless, even though they may be painful. They are often mistaken for corns or calluses, which are layers of dead skin that build up to protect an area which is being continuously irritated. A wart, however, is caused by a viral infection which invades the skin through small or invisible cuts and abrasions. Foot warts are generally raised and fleshy and can appear anywhere on the foot or toes. Occasionally, warts can spontaneously disappear after a short time, and then, just as frequently, they recur in the same location. If left untreated, warts can grow to an inch or more in circumference and can spread into clusters of warts. Children, especially teenagers, tend to be more susceptible to warts than adults.
Plantar warts, also known as verrucas, appear on the soles of the feet and are one of several soft tissue conditions that can be quite painful. Unlike other foot warts, plantar warts tend to be hard and flat, with a rough surface and well-defined boundaries. They are often gray or brown (but the color may vary), with a center that appears as one or more pinpoints of black. Plantar warts are often contracted by walking barefoot on dirty surfaces or littered ground. The virus that causes plantar warts thrives in warm, moist environments, making infection a common occurrence in public pools and locker rooms.
Like any other infectious lesion, plantar warts are spread by touching, scratching, or even by contact with skin shed from another wart. The wart may also bleed, another route for spreading. Plantar warts that develop on the weight-bearing areas of the foot (the ball or heel of the foot) can cause a sharp, burning pain. Pain occurs when weight is brought to bear directly on the wart, although pressure on the side of a wart can create equally intense pain.