Warts (verrucae) are small skin growths caused by any of 100 or more related human papillomaviruses.

• Raised or flat growths appear on any part of the skin.
• Most warts are painless.
• Doctors identify warts by sight or rarely do a biopsy.
• Warts that do not go away by themselves can be removed with chemicals, freezing, and/or burning and cutting.

Warts can develop at any age but are most common among children and least common among older people. People may have one or two warts or hundreds. 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 spread also 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 (see Sexually Transmitted Diseases: Genital Warts).

Most warts are harmless, although they may be quite bothersome. The exceptions are certain types of genital warts that sometimes cause cervical cancer in women.

Symptoms

Warts are classified by their location and shape. Some warts grow in clusters (mosaic warts), 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. 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 ½ 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.

Common Wart

Plantar 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. Plantar and palmar warts tend to be hard and flat, with a rough surface and well-defined boundaries. They are often tender and can be very painful when standing or walking, which puts pressure on plantar warts. 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.

Plantar Wart

Mosaic warts: Mosaic warts are clusters of smaller plantar or palmar warts that join together.

Periungual warts: Periungual warts are thickened, cauliflower-like growths around the nails. The nail may lose its cuticle, and other skin infections can develop around the nail. These warts are more common among people who bite their nails or have occupations where the hands are chronically wet such as dishwashers and bartenders.

Filiform warts: These warts are long, narrow, small growths that usually appear on the eyelids, face, neck, or lips. This type of wart is usually easy to treat.

Flat warts: Flat warts, which are more common among children and young adults, usually appear in groups as smooth, flat-topped, yellow-brown, pink, or flesh-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. 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 (see Sexually Transmitted Diseases: Genital Warts).

Did You Know... Warts are most often spread from one part of the body to another, but they can also spread from one person to another.

Diagnosis

Doctors recognize warts by their typical appearance. Growths on the skin that cannot be definitely identified may need to be removed for examination under a microscope (biopsy).

Treatment

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, but many can be prevented by a vaccine against the human papillomavirus. All types of warts may recur after removal. Plantar warts are the most difficult to cure.

In general, warts can be removed with the following:

• Chemicals: Typical chemicals used include salicylic acid, trichloroacetic acidSome Trade Names
  TRI-CHLOR
  , 5-fluorouracilSome Trade Names
  EFUDEX
  , cantharidinSome Trade Names
  CANTHARONE
  , tretinoinSome Trade Names
  AVITA RENOVA RETIN-A
  , and podophyllinSome Trade Names
  PODOFIN
  resin. Flat warts are often treated with peeling agents such as tretinoinSome Trade Names
  AVITA RENOVA RETIN-A
  or salicylic acid. 5-FluorouracilSome Trade Names
  EFUDEX
  cream or solution may also be used. ImiquimodSome Trade Names
  ALDARA
  can be used for the treatment of genital warts and is sometimes used to treat other warts. 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. The wart is scraped either at home or in the office to remove dead tissue before each treatment.
• Freezing (cryotherapy): Freezing is safe. It does not usually require that the area be numbed but may be too painful for children to tolerate. Warts may be frozen with various commercial freezing probes or with liquid nitrogen sprayed on or applied with a cotton swab. Cryotherapy is often used for plantar warts, filiform warts, and warts under the fingernails. Multiple treatments at monthly intervals are often required, especially for large warts.
• Burning and cutting: These methods are effective but are more painful and usually leave a scar. A laser or electrical current is used to burn warts off. A pulsed dye laser is also effective but, like freezing, usually requires multiple treatments (see Noncancerous Skin Growths: Using Lasers to Treat Skin Problems).

Last full review/revision January 2013 by James G. H. Dinulos, MD