Warts (verrucae) are small skin growths caused by human papillomavirus infection.
Warts are caused by human papillomaviruses.
Raised or flat growths appear on any part of the skin.
Most warts are painless.
Doctors identify warts by their appearance or rarely do a biopsy.
Warts that do not go away by themselves can be removed with chemicals, freezing, and/or burning and cutting.
Vaccines protect against some of the types of human papillomavirus that cause warts.
Warts are caused by human papillomavirus (HPV) infection. There are over 100 types of HPV.
Warts can develop at any age but are most common among children and least common among older adults. People may have one or two warts or hundreds.
Warts are contagious. Because prolonged or repeated contact is necessary for the virus to spread, warts are most often spread from one area of the body to another, but they can also spread from one person to another. There usually needs to be a break in the skin for spread to occur, but the break can be extremely small. Sexual contact is often sufficient to spread genital warts.
Most warts are harmless, although they may be quite bothersome. The exceptions are certain types of genital warts that are due to HPV types that can cause cancer of the mouth, throat, cervix, or genitals.
Symptoms of Warts
Warts are classified by their location on the skin and shape.
Some warts grow in clusters, but others appear as isolated, single growths.
Most warts are painless, but some hurt when touched. Warts on the feet can cause pain when standing or walking.
Warts may have black dots, particularly if shaved.
Common warts
Common warts (also called verrucae vulgaris), which almost everyone gets, are firm growths that usually have a rough surface.
They are round or irregularly shaped; are light gray, yellow, brown, or gray-black; and are usually less than 1/2 inch (about 1 centimeter) across.
Generally, they appear on areas that are frequently injured, such as the knees, face, fingers, and elbows. Common warts may spread to surrounding skin.
Plantar warts and palmar warts
Plantar warts develop on the sole of the foot, where they are usually flattened by the pressure of walking and are surrounded by thickened skin.
Palmar warts develop on the palm of the hand.
Plantar and palmar warts tend to be hard and flat, with a rough surface and well-defined boundaries. They are often tender, and plantar warts can be very painful when standing or walking, which puts pressure on them.
Warts may appear on the top of the foot or on the toes, where they are usually raised and fleshier.
Warts are often gray or brown and have a small black center.
Unlike corns and calluses, plantar warts tend to bleed from many tiny spots, like pinpoints, when a doctor shaves or cuts the surface away with a knife.
Mosaic warts
Mosaic warts are clusters of smaller plantar warts that join together. Like other plantar warts, they are often tender.
Periungual warts
Periungual warts are thickened, cauliflower-like growths around the nails. (Warts that grow under the nails are called subungual warts.)
The nail may lose its cuticle, and other skin infections (such as paronychia) can develop around the nail.
These warts are more common among people who bite their nails or have an occupation where their hands are chronically wet such as dishwashing and bartending.
Filiform warts
These warts are long, narrow, branch-like growths that usually appear on the eyelids, face, neck, or lips.
This type of wart usually does not cause symptoms and is usually easy to treat.
Flat warts
Flat warts usually appear in groups as smooth, flat-topped, yellow-brown, pink, or skin-colored spots, most frequently on the face and tops of the hands. They can also develop along scratch marks. The beard area in men and the legs in women are also common locations for flat warts, where they may be spread by shaving.
Flat warts are more common among children and young adults.
This type of wart typically causes no symptoms but is usually difficult to treat.
Genital warts
Also called venereal warts or condylomata acuminata, genital warts occur on the penis, anus, vulva, vagina, and cervix.
They can be flat, smooth, and velvety or irregular, bumpy growths often with the texture of a small cauliflower.
Genital warts usually do not cause symptoms, but warts around the anus often itch.
Image courtesy of Joe Millar via the Public Health Image Library of the Centers for Disease Control and Prevention.
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Diagnosis of Warts
A doctor's evaluation
Rarely biopsy
Doctors recognize warts by their typical appearance.
Growths on the skin that cannot be definitively identified may need to be removed for examination under a microscope (biopsy).
Treatment of Warts
Topical chemicals
Freezing
Burning or cutting
Other therapies
Many warts, particularly common warts, disappear on their own within a year or two. Because warts rarely leave a scar when they heal spontaneously, they do not need to be treated unless they cause pain or psychologic distress.
Genital warts are treated to prevent spread to a sex partner (see Treatment of HPV Infection).
All types of warts may return after removal. Plantar warts are the most difficult to cure.
Warts can be removed in several ways. Some of these treatments are more effective for certain types of warts.
Chemicals
Topical chemicals are applied directly to the wart. They come in various forms, such as creams, gels, lotions, or solutions.
Some chemicals can be applied by the person, but others must be applied by a doctor. Most of these chemicals can burn normal skin, so when they are applied at home, directions must be followed carefully. Chemicals usually require multiple applications over several weeks to months. Before applying chemicals to the wart, the wart can first be soaked in hot water to make it easier for the chemicals to penetrate it. The wart is scraped either at home or in the office to remove dead tissue before each treatment.
Freezing (cryotherapy)
Warts may be frozen with various commercial freezing probes. However, liquid nitrogen sprayed on or applied with a cotton swab is more effective.
Freezing is safe when it is done by a trained health care professional. The area usually does not need to be numbed, but freezing with no numbing may be too painful for children to tolerate.
Cryotherapy is often used for plantar warts, filiform warts, and periungual warts.
Multiple treatments at monthly intervals are often required, especially for large warts.
Burning (electrosurgery) and cutting
A laser can be used to burn off warts. Like with freezing, multiple treatments usually are required (see Using Lasers to Treat Skin Problems).
A wart may be removed by scraping and burning it with an electric needle (a procedure called curettage and electrodesiccation).
A wart can also be removed surgically either by shaving it off with a razor or using a scalpel blade to cut it out.
These methods are effective but are more painful and usually leave a scar. An anesthetic is injected for some of these procedures.
Other therapies
An antigen made with the yeast Candida can be injected directly into warts, particularly warts that are difficult to treat. This antigen comes from the yeast. When injected into a wart, it causes an immune response that fights against the virus.
The HPV vaccine that protects against 9 strains of HPV may be helpful for children who have warts that are difficult to treat.
Prevention of Warts
HPV vaccines protect against some of the types of HPV that cause warts and cancer.
