Dermatology A to Z


What Causes Warts?

Warts are harmless skin growths caused by a virus (Human Papilloma Virus or HPV). Warts can grow on any part of the body. Their appearance depends on their location. On the face and tops of the hands, warts protrude, whereas on pressure areas such as the palms of the hand and soles of the feet, they’re pushed inward. Warts on the bottoms of the feet (called plantar warts) grow inward from the pressure of standing and walking and are often painful. Warts have a rough surface on which tiny dark specks can often be seen. Warts are common and can be a nuisance. They may bleed if injured. Common warts never turn cancerous. Since warts are caused by a virus, they are slightly contagious. Warts may spread on the body since they are infectious agents. We don’t know why some individuals get warts easily, while others never get them. There is no way to prevent warts. People have been trying to cure warts for thousands of years. The “success” of folk remedies for warts is due to the fact that warts often disappear by themselves, especially in young children. This spontaneous disappearance is less common in older children and adults.


There is no single perfect treatment for warts, since we are unable to kill the virus. Treatment consists of destroying the wart or stimulating an immune response to the virus. Warts can be destroyed with surgery, by freezing with liquid nitrogen, or with chemicals. The treatment to be used on your warts depends on the location and size, your type of skin, and my professional judgment. Sometimes new warts will form while existing ones are being destroyed. All we can do is treat the new warts when they become large enough to be seen. No matter what treatment is used, warts occasionally fail to disappear. Warts may return weeks or months after an apparent cure. Don’t become concerned if a wart recurs. Please keep all follow-up appointments since a small residual wart may be present. The treatment will be repeated, or a different method will be used to destroy the wart.

SURGERY Since the wart virus lives only in the superficial skin (epidermis), scalpel surgery is not appropriate. It will leave a scar and may spread the virus deeper.

CHEMICALS Many chemical preparations are available over-the-counter and by prescription. Such solutions vary in their strength and ability to harm normal tissue. Instructions for using the over-the-counter preparations are in the boxes, on the bottles or on a separate sheet. The strongest treatments are only applied by a physician in the office.

LASER The pulse-dye laser can be an effective tool for treating warts. It can be painful and will leave the wart bruised for several weeks.

CAUTERY or CURRETTAGE Some warts resistant to chemical therapy and in especially difficult locations (underneath fingernails etc) may be burned off by laser or electric current, or scraped off (curetted) with a sharp instrument. These measures are in general not used in children and not for all warts. Such treatments are painful, require local anesthesia, and leave scars.

LIQUID NITROGEN Freezing is one of the mainstays of wart treatment. Freezing sessions are usually 3-4 weeks apart. Time between is necessary for healing. This therapy is effective and leaves little scarring.

CANTHERONE This compound is obtained from the blister beetle found in Central Africa. Prolonged contact with the compound will cause a blister to form. Application is not painful, though the wart/blister can become quite sore at 24 hours.

CANDIN This is a protein that comes from the yeast Candida. The Candin is injected into 1 or 2 warts every month. The body is tricked into thinking there is a yeast present and soon, stumbles across the wart virus. Once this happens, all the warts will disappear.

IMMUNE MODULATORS Aldara works by locally stimulating the immune system to fight the wart virus. While this treatment can take several months to work, in some people, it is quite successful. The main side effect is local irritation, though only in some individuals.

SQUARIC ACID This compound causes an allergic reaction similar to poison ivy. Initially, you are made allergic to the squaric acid. After this is accomplished, each week a thin application is made to the wart(s) by the nurse in the office. It is quite successful but may take 2 – 4 months of weekly visits.

CHILDREN Warts spontaneously disappear in most small children. It is best to avoid painful therapies in children. Chemical treatments and paring at the wart with emery boards and pumice (do not cause bleeding or pain!) are usual approaches. Better yet, give them time to resolve spontaneously if only one or two are present.