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Patient information: Skin warts (Beyond the Basics)

SKIN WARTS OVERVIEW

Common skin warts (also called cutaneous warts) are raised round or oval growths. A wart may be lighter or darker than the skin around it. Some warts may have tiny black dots in them, often called seeds. The dots are small, clotted blood vessels. Warts may occur alone or in larger groups that merge and form patches.

You can become infected with the virus that causes warts (human papillomavirus) by touching another person's wart. The virus is more likely to infect skin that is injured or softened by water, but it can infect healthy skin as well. It can take up to six months after exposure to the virus for a wart to appear.

Who gets skin warts? — Skin warts are most common in children and young adults. They are also more common among people with certain jobs, such as handling meat, fish, and poultry. People who have chronic skin conditions, such as eczema, and people with a weakened immune system (eg, from AIDS or after an organ transplant) may have more extensive warts or warts that are difficult to control.

Where do warts occur? — Skin warts can occur in the following locations:

Common skin warts, also called verruca vulgaris, can occur on any area of skin, but are often seen on the fingers, hands, knees, and elbows (picture 1).

When common warts are located around the fingernails, they are called periungual warts (picture 2).

Plantar warts are found on the soles of the feet (picture 3)

Flat warts are most commonly found on the back of the hands, face, and lower legs (picture 4A-B)

SKIN WART DIAGNOSIS

Skin warts can usually be diagnosed based upon how they look. Skin biopsy or other testing is not usually necessary.

SKIN WART TREATMENT

Treatment of warts depends upon where the wart is located and how much it bothers you. Treatment is not necessary in all cases because about two-thirds of skin warts will resolve on their own within two years, without treatment. However, during this time, the wart may enlarge or new warts may appear. In addition, a few small warts are usually easier to treat than multiple larger warts. For these reasons, most people choose to treat skin warts.

There are many ways to treat warts, and the "best" treatment depends upon your and your healthcare provider's preferences and any underlying medical problems. Most treatments take several weeks or even months to work, and warts can come back after treatment.

Treatment of skin warts is also discussed in more detail in a separate article. (See "Cutaneous warts".)

Treatments you can use at home

Salicylic acid — Salicylic acid is a type of acid that is applied directly to the wart. It comes in different forms, such as a liquid or patch. Some forms of salicylic acid can be applied at home, while others must be applied by a healthcare provider.

Salicylic acid is useful for most types of skin warts and can be used in children. (See 'Duct tape' below.)

If you decide to try salicylic acid treatment at home, you should first soak the area in warm water for 10 to 20 minutes (to soften the skin) and dry the skin completely. Apply the liquid or patch to the wart at bedtime and leave it in place overnight. Between treatments, you should use a nail file or pumice stone to gently slough off dead skin from the surface of the wart. It is normal to have some skin irritation or light bleeding during treatment; this is a sign that the treatment is working.

You should continue treatment for one to two weeks after the wart is gone to be sure that the virus is gone.

If you have neuropathy (nerve damage that causes numbness), you should not use salicylic acid. In people with neuropathy, salicylic acid could potentially injure the skin without the person being aware of the injury.

Duct tape — Duct tape, a sticky tape available at most home improvement stores, has been used to treat skin warts. It is not clear how duct tape works or if it is an effective treatment. Some studies have shown success while others have not.

If you choose to try duct tape, silver duct tape is preferred over clear tape because it sticks to the skin better. You should cover the skin wart with tape and leave it in place for six days. You then remove the tape, soak the skin in warm water for 10 to 20 minutes, and use and emery board or pumice stone to gently slough off dead skin. Leave the skin uncovered for one night, then reapply the tape for another six nights.

Most people who find duct tape an effective treatment have resolution of their skin warts within four weeks. Warts are unlikely to respond if you do not see any improvement within two weeks.

Duct tape treatment is not recommended if you have diabetes, nerve damage (neuropathy), peripheral artery disease, or any condition that causes the skin to be irritated. In these people, duct tape may cause complications, such as skin sores or infection.

Prescription treatments

Liquid nitrogen — Liquid nitrogen is a very cold liquid that destroys warts by freezing the skin (also called cryotherapy). Liquid nitrogen must be applied by a healthcare provider, and multiple treatments are often needed to eliminate the wart.

Liquid nitrogen may be recommended for skin wart treatment in older children and adults, but it is not usually recommended for younger children because it can be painful. You may be given local anesthesia before treatment with liquid nitrogen to decrease pain.

After treatment, most people heal within four to seven days. Home treatment with salicylic acid is usually recommended for at least one week after the skin heals to reduce the chances of the wart coming back.

People with dark skin can develop permanent loss of skin color in areas treated with liquid nitrogen. If you have concerns about how your skin will appear after treatment with liquid nitrogen, talk to your healthcare provider.

Cantharidin — Cantharidin is a liquid that is applied by a healthcare provider to treat skin warts. It may be particularly useful for young children because it causes no pain initially. However, some people (although not all) develop pain, blisters, and swelling 2 to 24 hours after the treatment.

The skin usually heals within 5 to 10 days after treatment. Most providers recommend treatment with salicylic acid for at least one week after the skin heals to reduce the chances of the wart coming back.

Shave excision — Shave excision is a procedure that involves removing a skin wart with a blade. A healthcare provider performs the procedure, usually after injecting local anesthesia to numb the skin.

5-Fluorouracil — 5-Fluorouracil is a prescription cream that can be used to treat flat warts. You apply the cream to the affected area twice a day for three to five weeks. During treatment, it is important to protect the treated area from the sun because sun exposure can worsen skin irritation. (See "Patient information: Sunburn prevention (Beyond the Basics)".)

Imiquimod — Imiquimod cream (Aldara®) is a prescription cream that works by stimulating the immune system to eliminate the wart. You apply the cream at bedtime several times per week. It is normal to develop some skin irritation during treatment.

Imiquimod is more expensive than other wart treatments, but may be recommended in certain situations (for children, if other treatments are not effective, or if scarring is a concern).

Immunotherapy — Immunotherapy involves injecting a substance directly into the wart to trigger an immune response. Your clinician may repeat the injection every three weeks (up to five injections) until the wart completely clears up. Salicylic acid and/or duct tape may be used in addition to immunotherapy.

The advantage of this type of treatment is that it does not leave scars and is less expensive than imiquimod.

Other treatments — Other wart treatments are available, and may be recommended if you do not respond to one of the treatments discussed above. (See "Cutaneous warts".)

WHEN TO SEEK HELP

Consult a healthcare provider if:

You are not sure if you skin growth is a wart

Your skin wart does not improve with home treatment

You would like to use home treatment, but are not sure which treatment is right for you

You have been treated for warts and have developed signs of a skin infection, such as redness, pain, or pus-like drainage from the treated area. In some cases, redness and pain are normal reactions after wart treatment, so discuss possible side effects with your healthcare provider in advance.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Skin warts (The Basics)
Patient information: Seborrheic keratosis (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

This topic currently has no corresponding Beyond the Basics content

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Cutaneous warts
Epidemiology of human papillomavirus infections

The following organizations also provide reliable health information.

KidsHealth

     (http://kidshealth.org/parent/infections/skin/wart.html)

Medline Plus

     (www.nlm.nih.gov/medlineplus/ency/article/000885.htm, available in Spanish)

American Academy of Dermatology

     (www.aad.org/public/publications/pamphlets/common_warts.html)

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Literature review current through: Jun 2014. | This topic last updated: Dec 17, 2013.
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