Warts

What are warts?

Warts are non-cancerous skin growths caused by a viral infection in the top layer of the skin. Viruses that cause warts are called human papillomavirus (HPV). Warts are usually skin-colored and feel rough to the touch, but they can be dark, flat and smooth. The appearance of a wart depends on where it is growing.

What causes warts?

Warts are passed from person to person, sometimes indirectly. The time from the first contact to the time the warts have grown large enough to be seen is often several months. The risk of catching hand, foot, or flat warts from another person is small.

Types of Warts

  • Common warts – usually grow on the fingers, around the nails and on the backs of the hands. They are more common where skin has been broken, for example where fingernails are bitten or hangnails picked. These are often called “seed” warts because the blood vessels to the wart produce black dots that look like seeds. Common warts in young children can be treated at home by their parents by applying salicylic acid gel, solution or plaster on a daily basis. Warts may also be treated by “painting” with cantharidin in the dermatologist’s office. Cantharidin causes a blister to form under the wart. For adults and older children cryotherapy (freezing) is generally preferred. Electrosurgery (burning) is another good alternative treatment. Laser treatment can also be used for resistant warts that have not responded to other therapies.
  • Foot warts – are usually on the soles (plantar area) of the feet and are called plantar warts. When plantar warts grow in clusters they are known as mosaic warts. Most plantar warts do not stick up above the surface like common warts because the pressure of walking flattens them and pushes them back into the skin. Like common warts, these warts may have black dots. Plantar warts have a bad reputation because they can be painful, feeling like a stone in the shoe. Treatments include the use of salicylic acid plasters, applying other chemicals to the wart, or one of the surgical treatments including laser surgery, electrosurgery, or cutting.
  • Flat warts – are smaller and smoother than other warts. They tend to grow in large numbers – 20 to 100 at any one time. They can occur anywhere, but in children they are most common on the face. In adults they are often found in the beard area in men and on the legs in women. Irritation from shaving probably accounts for this.

What are some of the other treatments for warts?

  • Laser therapy is used to destroy some types of warts. Lasers are more expensive and require the injection of a local anesthesia to numb the area.
  • Another treatment is to inject each wart with an anti-cancer drug called bleomycin. The injections may be painful and can have other side effects.
  • Immunotherapy attempts to use the body’s own rejection system. Several methods of immunotherapy are being used. With one method the patient is made allergic to a certain chemical which is then painted on the wart. A mild allergic reaction occurs around the treated warts and may result in the disappearance of the warts.
  • Warts may also be injected with interferon, a treatment to boost the immune reaction and cause rejection of the wart.

What about the problem of recurrent warts?

Sometimes it seems as if new warts appear as fast as old ones go away. This may happen because the old warts have shed virus into the surrounding skin before they were treated. In reality new “baby” warts are growing up around the original “mother” warts. The best way to limit this is to treat new warts as quickly as they develop so they have little time to shed virus into nearby skin. A check by your dermatologist can help assure the treated wart has resolved completely.