Plantar warts are growths that appear on the bottom of the foot. These growths, called warts, are noncancerous; they are caused by a viral infection called the human papillomavirus, or HPV. There are many strains of HPV, and the strain that causes warts to grow on the hands and feet is different from the strain that causes warts on the genitals.
Most warts will disappear on their own within two years. However, due to their position, plantar warts can be painful when a person bears weight on his or her foot, causing the person to seek medical treatment.
Warts are transferred through indirect contact. If a person with a plantar wart showers without shower shoes, or walks around barefoot, another person can pick up the virus. It then enters through small cuts or breaks in the skin.
Children and teenagers are more likely to develop warts than adults. Other risk factors include a weakened immune system, having had warts in the past, and walking around barefoot in public places which are wet or damp (like a locker room or a pool).