What are warts?
Warts are non-cancerous skin growths caused by a viral infection in the top layers of skin. The virus that causes warts is called the human papilloma virus, or 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 upon where it is growing.

How many kinds of warts are there?
There are several different kinds of warts including:

• Common warts
• Plantar warts
• Flat warts
• Genital Warts 

Common Warts (verruca vulgaris) usually grow on the fingers, around the nails, and on the backs of the hands.  They are more common in skin that has been broken, such as areas where fingernails have been bitten or hangnails have been picked.  These are often called “seed” warts because the blood vessels to the warts produce black dots that look like seeds. 

Plantar Warts (verruca plantaris) are common warts located on the sales of the feet.  Warts on the palms (verruca palmaris) would be called palmar warts.  When many small plantar warts grow in clusters, they are known as mosaic warts because they fit together like mosaic tiles, making them more stubborn to treat.  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.  Black dots may also be seen in these warts.  Plantar warts have a bad reputation because they can be painful and feel like a stone in the shoe.

Flat Warts (verruca-plana) 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 are most common on the face, in the beard area in men, and on the legs in women.  Irritation or microscopic cuts in the skin from shaving probably contribute to them.

Genital Warts (condylomata acuminata) are usually sexually transmitted and can be spread from close physical contact and repeated exposures.  They are also seen in infants who have been delivered vaginally to mothers with HPV in their genital tract.  Genital warts are flesh-colored, and may be rough or smooth.  They can be large or small and found as a single growth or in groups.  Genital warts appear on the genitals, inside the vagina, on the cervix, or around the anus.

Why do some people get warts and others do not?
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.  Just as some people catch colds very easily, some people are more likely to catch the wart virus than others.

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 multiplying rapidly 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?
A variety of treatments are available depending upon the age of the patient, the location of the wart, and the type of wart.

• Salicylic acid gels, solutions, or plasters may be prescribed for daily home treatments.  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.

• Cantharidin is a chemical that can be applied in the dermatologist’s office.  It 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, and re-treat the remaining wart if necessary.

• Cryotherapy is freezing with a cold liquid gas called liquid nitrogen.  This treatment causes a blister to form which can be clipped in a week; repeat treatment at one to three week intervals is usually required.

• Cryotherapy may be painful, but can result in scarring.

•  Electrosurgery (burning) is performed in the dermatologist’s office.  It destroys the wart immediately. Time is needed to heal the area.

• Laser treatment can also be used for resistant warts that have not responded to other therapies.

• Surgery or cutting may be used to remove the wart.

• Imiquimod is a cream that causes an inflammatory response which makes the wart go away.  It may be applied at home and is especially good for genital warts.

• Bleomycin is an anti-cancer drug that may be injected into each wart.  This may be painful and may produce other side effects, but can be used for stubborn warts.

• Interferon is injected into warts to boost the immune reaction and cause rejection of the wart.  This may produce flu-like side effects.

• Immunotherapy attempts to use the body’s own rejection system. Several methods of immunotherapy can be used.  With one method, the patient is made allergic to certain chemicals which are then painted on the wart.  A mild allergic reaction occurs around the treated warts and may result in their disappearance.

Special Cases
Plantar warts are difficult to treat because the bulk of the wart lies below the skins surface.  Treatments may vary and include salicylic acid plasters, other chemicals, and surgical treatments.  The dermatologist may recommend a change in footwear to reduce pressure on the wart, and ways to keep the foot dry.

What about tile use of hypnosis or “folk” remedies?
Some people believe folk remedies and hypnosis are effective.  Since warts, especially in children, may disappear without treatment, it is hard to know whether it was the result of a folk remedy or just the passage of time that led to the cure.

Should I see a dermatologist?
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 a dermatologist’s advice.

Is there any research going on about warts?
Advances in new treatments, as well as the development of a vaccine against warts is ongoing .

To learn more about warts, visit www.aad.org, or see your dermatologist.


AAO Web site: www.aad.org
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© 2004 American Academy of Dermatology
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