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 also be dark, flat and smooth. The appearance of a wart depends on where it is growing.

How many kinds of warts are there?

There are several different kinds of warts, including:

• Common warts
• Foot (plantar) warts
• Flat 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.

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.

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.

How do you get 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.

Why do some people get warts and others don't?

Some people get warts depending on how often they are exposed to the virus. Wart viruses occur more easily if the skin has been damaged in some way, which explains the high frequency of warts in children who bite their nails or pick at hangnails. Some people are just more likely to catch the wart virus than others, just as some people catch colds very easily. Patients with a weakened immune system also are more prone to a wart virus infection.

Do warts need to be treated?

In children, warts can disappear without treatment over a period of several months to years. However, warts that are bothersome, painful, or rapidly multiplying should be treated. Warts in adults often do not disappear as easily or as quickly as they do in children.

How do dermatologists treat warts?

As dermatologists, we are trained to use a variety of treatments depending on the age of the patient and the type of wart.

Common warts - In young children, common warts can be treated at home by their parents on a daily basis by applying salicylic acid gel, solution or plaster. There is usually little discomfort, but it can take many weeks of treatment to obtain favorable results. Treatment should be stopped at least temporarily if the wart becomes sore. Warts may also be treated by "painting" with cantharidin in the dermatologist's office. Cantharidin causes a blister to form under the wart. The dermatologist can then clip away the dead part of the wart in the blister roof in a week or so.

For adults and older children, cryotherapy (freezing) is generally preferred. This treatment is not too painful and rarely results in scarring. However, repeat treatments at one-to-three week intervals are often necessary. 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 – These are difficult to treat because the bulk of the wart lies below the skin surface. 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. The dermatologist may recommend a change in footwear to reduce pressure on the wart and ways to keep the foot dry since moisture tends to allow warts to spread.

Flat warts – These are often too numerous to treat with the methods mentioned above. As a result, "peeling" methods using daily applications of salicylic acid, tretinoin, glycolic acid or other surface-peeling preparations are often recommended. For some adults, periodic office visits for surgical treatments are sometimes necessary.

What are some of the other treatments for warts?

There are several different lasers used for the treatment of 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 treated.

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, which attempts to use the body's own rejection system, is another method of treatment. Several methods of immunotherapy are being used. With one method, the patient is made allergic to a certain chemical that is then painted on the wart. A mild allergic reaction occurs around the treated warts and may result in their disappearance.

Warts may also be injected with interferon, a treatment to boost the immune reaction and cause rejection of the wart.

Can I treat my own warts without seeing a doctor?

There are some wart remedies available without a prescription. However, you might mistake another kind of skin growth for a wart and end up treating something more serious as though it were a wart. If you have any questions about either the diagnosis or the best way to treat a wart, you should seek your dermatologist's advice.

What about the use of hypnosis or "folk" remedies?

Many people, patients and doctors alike, believe folk remedies and hypnosis are effective. Since warts, especially in children, may disappear without treatment, it's hard to know whether it was a folk remedy or just the passage of time that led to the cure. Since warts are generally harmless, there may be times when these treatments are appropriate. Medical treatments can always be used if necessary.

What about the problem of recurrent warts?

Sometimes it seems as if new warts appear as fast as the old ones go away. This may happen because the old warts have shed viral particles 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 the new warts as quickly as they develop so they have little time to shed the virus into nearby skin. A check by your dermatologist can help assure the treated wart has resolved completely.

Is there any research going on about warts?

Research is moving along very rapidly. There is great interest in new treatments as well as the development of a vaccine against warts. We hope there will be a solution to the annoying problem of warts in the not-too-distant future. And yes, duct tape has been shown to cure warts! It must be applied and left on for three days and then reapplied. This is done continuously until the wart disappears. (It may work, but don’t hold your breath!)