Causes of Warts

Health Articles > Warts > What Causes Warts?

Warts are small skin growths that are caused by a virus – the human papillomavirus or HPV.   There are 100 or more types of HPV.  Some types of HPV cause relatively harmless conditions, such as common warts, while others may cause serious diseases.  Different types of HPV cause different types of warts.  Warts are benign – that is non cancerous.  The virus causes the wart to occurs when keratin (which is a hard protein in the top layer of the skin) grows too fast.

Warts should not be confused with moles.  Moles are often dark and can grow quite large while warts are usually small, skin-colored and rough to the touch.  They can grow almost anywhere on the body  but the most common places are the hands, fingers, face and feet.   Warts on the soles of the feet are called plantar's warts.

Like other infectious diseases, wart viruses pass from person to person.  But you can also get the wart virus by touching a personal item such as a towel or clothing that has recently been used by someone else who has the virus.  In the case of plantar warts on the feet, it is easy to pick up the virus when walking barefoot in public areas such as the paving around a swimming pool, public showers or locker rooms.

So warts are contagious and children are the most susceptible to them because their immune system is less mature.  Each person's immune system responds to the HPV virus differently, meaning not everyone who comes in contact with HPV develops warts.

If you have warts, you can spread the virus to other places on your own body. Warts usually spread through breaks in your skin, such as a hangnail or scrape. Biting your nails also can cause warts to spread on your fingertips and around your nails.  A wart will not necessarily develop straight away.  It can take a wart as long as two to six months to develop after exposure to the virus.

The most often seen types of warts are:

  • Common warts which are the familiar type of dome-shaped warts on the backs of fingers, toes, and knees.  Although they are considered to be contagious, it is very common for just one family member to have them. In addition, they often affect just one part of the body (such as the hands or the feet) without spreading over time to other areas.
  • Plantar's warts are found on the bottom of the foot. The pressure of walking or standing on them flattens them so they can become very painful.  They can be dotted with very small clotted blood vessels that look like dark pinpoint spots – some people think they are roots.  Sometimes plantar warts are confused with corns.
  • Flat or plane warts  may arise on the face, legs, and other parts of the body, often very small (the size of a pin head) and in large numbers.
  • Periungual warts are warts that occur around or under the nail.
  • Filiform warts typically appear as a single long stalk, often on the face.