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Plantar wartsBy Mayo Clinic staff
Original Article: http://www.mayoclinic.com/health/plantar-warts/DS00509
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Plantar warts are noncancerous skin growths on the soles of your feet caused by the human papillomavirus (HPV), which enters your body through tiny cuts, breaks or other vulnerable sites on the skin of your feet.
Plantar warts often develop beneath pressure points in your feet, such as the heels or balls of your feet. This pressure also may cause a plantar wart to grow inward beneath a hard, thick layer of skin (callus).
Most plantar warts aren't a serious health concern and may not require treatment. However, plantar warts can be bothersome or painful. If self-care treatments for plantar warts don't work, you may need to see your doctor to have them removed.
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Signs and symptoms of plantar warts include:
- Small, fleshy, grainy lesions, or growths, on the soles of your feet
- Hard, thickened skin (callus) over a well-defined "spot" on the skin, where a wart has grown inwards
- Black pinpoints, which are commonly called "wart seeds" but are actually small, clotted blood vessels
- Lesions that interrupt the normal lines and ridges in the skin of your feet
- Pain or tenderness when walking or standing
When to see a doctor
See your doctor if:
- The lesions are painful or change in appearance or color
- The warts persist, multiply or recur, despite home treatment
- The warts interfere with your activities
- You have diabetes or nerve damage (neuropathy) in your feet — in which case, you should not use at-home treatments
- You have a weakened immune system because of HIV/AIDS, immune-suppressing drugs or other immune system disorders
- You have any doubt that the lesion is a wart
In these cases, your doctor may prescribe a closely monitored treatment plan or consider a different diagnosis.
Plantar warts are caused by an infection with the human papillomavirus (HPV) in the outer layer of skin on the sole of your feet.
There are more than 100 types of HPV, but only a few types are known to cause warts on your feet. Other types of HPV are more likely to cause warts on other areas of your skin or on mucous membranes.
Transmission of the virus
Each person's immune system responds differently to HPV, so not everyone who comes in contact with the virus develops warts. Even people in the same family react to the virus differently.
The HPV strains that cause plantar warts aren't highly contagious. Therefore, it isn't easily transmitted by direct contact from one person to another. However, the virus does thrive in warm, moist environments — such as shower floors, locker rooms and public swimming areas. Consequently, you may contract the virus by walking barefoot around pools or gyms.
The virus also needs to have a point of entry into the skin:
- Cracks in dry skin
- Cuts or scrapes
- Wet, softened, fragile skin from prolonged water exposure (macerated skin)
If the virus spreads from the original site of infection, multiple warts may appear. These may include:
- Several individual warts at different sites on the foot
- "Kissing warts," a pair of warts that appear where two parts of the foot touch, such as a point of contact between two toes or between a toe and the ball of foot
- Mosaics, clusters of warts that essentially form a large, single lesion
Anyone can develop plantar warts, but they are more likely to affect:
- Children and teenagers
- People with weakened immune systems
For reasons doctors don't understand, some people are more susceptible to the wart-causing virus than others.
When plantar warts cause pain, you may alter your normal posture or gait — perhaps without realizing the change. A difference in how you stand, walk or run can eventually cause muscle or joint discomfort.
Preparing for your appointment
You'll likely start by seeing your family doctor or primary care doctor. However, you may be referred to a specialist in skin diseases (dermatologist).
The following tips can help you prepare for your appointment.
What to expect from your doctor
Your doctor is likely to ask you a number of questions, such as:
- When did the lesion or lesions first appear?
- Have they changed significantly in size or appearance?
- Does the condition cause any pain?
- Have you had warts before?
- Have you been diagnosed with diabetes or nerve damage in your feet?
- Do you have any condition or take any medication that is known to weaken your immune system?
- What at-home treatments have you used and how long have you used them?
- What effect have you noticed with these treatments?
- Do you use a public pool or shower at a gym — common places for exposure to a wart-causing virus?
What you can do
Bring a list of all medications you take regularly — including over-the-counter medications and dietary supplements — and the daily dosage of each.
You may also want to write down questions for your doctor:
- If I have a plantar wart, can we start with at-home care?
- If we choose that approach, under what conditions should I call you?
- If the first treatment doesn't work, what will we try next?
- If the lesion isn't a plantar wart, what tests would you need to do?
- How long will it take to get results?
What you can do in the meantime
If you're certain that you have a plantar wart, you can begin using home remedies or alternative medicines. If you have diabetes, nerve damage in your feet or a compromised immune system, don't use self-care remedies without consulting your doctor.
If pressure on the wart causes pain, you may want to wear well-cushioned shoes, such as athletic shoes, that evenly support the sole and relieve some pressure on the wart. Avoid wearing dress shoes or other less comfortable shoes if possible.
Tests and diagnosis
In most cases, your doctor can diagnose a plantar wart by examining the lesion on your foot. If there's any doubt, your doctor may need to pare down the lesion with a scalpel. Plantar warts will show signs of dark, pinpoint dots — tiny clotted blood vessels.
If there's still doubt about the diagnosis, your doctor may remove a small section of the lesion (shave biopsy) and send it to a laboratory for analysis.
Treatments and drugs
Plantar warts often don't require treatment. Most warts resolve on their own without treatment within a couple of years. However, if they are causing pain or spreading, they should be treated. It's much easier to treat a few small warts than several large warts.
Plantar warts can stubbornly resist treatment. Therefore, most treatments require patience, persistence and multiple interventions.
People with diabetes, nerve damage in their feet or weakened immunity need treatment under a doctor's supervision. Your doctor will closely monitor the treatment effect and the quality of wound healing.
Treatments provided by your doctor
If home remedies aren't working, your doctor may recommend other treatments. Doctors generally start with the method that is least likely to result in pain, side effects and scarring. Scarring on the sole of the foot can be painful and is usually irreversible. Treatments often need to be repeated, and warts may return at a later time.
Treatment options include the following:
- Freezing (cryotherapy). Your doctor can apply liquid nitrogen with a spray canister or cotton-tipped applicator to freeze and destroy your wart. The chemical causes a blister to form around your wart, and the dead tissue sloughs off within a week or so. The application itself can be painful, and cryotherapy can result in painful or tender blisters that resolve on their own.
- Cantharidin. Your doctor may use cantharidin — a substance extracted from the blister beetle — on your plantar warts. Typically, the extract is paired with salicylic acid, applied to the plantar wart and covered with a bandage. The initial application is painless, but the subsequent blister that forms can be quite painful. Your doctor clips away the dead part of the wart in about a week.
- Immunotherapy. This therapy attempts to harness your body's immune system to remove tough-to-treat warts. This can be accomplished in a couple of ways. Your doctor may inject your warts with interferon, a medication that boosts your immune system's instinct to reject warts. Or your doctor may inject your warts with a foreign substance (antigen) that stimulates your immune system. Doctors often use mump antigens, because many people are immunized against mumps. As a result, the antigen sets off an immune reaction that may fight off warts. Interferon treatment may result in flu-like symptoms for a few hours after treatment. Both treatments may cause pain.
- Imiquimod (Aldara). This prescription cream applied directly to a wart is an immunotherapy medication that encourages your body to release immune system proteins (cytokines) to attack HPV. This treatment can result in severe inflammation near the site and damage to the tissues beyond the wart. If this occurs, the treatment is dropped. The drug may also result in flu-like symptoms that may lessen with a lower dosage.
- Minor surgery. This involves cutting away the wart or destroying the wart by using an electric needle in a process called electrodesiccation and curettage. Your doctor will anesthetize your skin before this procedure. This treatment is avoided if possible with plantar warts because of the risk of scarring.
- Laser treatment. A type of laser treatment called pulse dye laser treatment burns closed (cauterizes) tiny blood vessels. The infected tissue eventually dies, and the wart falls off. This treatment can cause pain and scarring.
With each of these treatments, your doctor will provide instructions about how to cover a wart or wound, remove dead tissue between appointments, clean the site, and change a dressing if needed.
Your doctor may also direct you to use over-the-counter wart treatments along with these treatments or between visits to the office. He or she may also recommend the use of an antibiotic cream to protect the site from common infections after a wart has been removed or after a treatment-related blister has broken.
Lifestyle and home remedies
The following self-care approaches can help you treat plantar warts. Do not treat plantar warts at home if you have an impaired immune system, diabetes or nerve damage in your feet. Over-the-counter treatment options include the following:
- Salicylic acid. Nonprescription wart medications with salicylic acid are sold as a patch or liquid that destroys and peels off layers of infected skin a little bit at a time. Usually, you're instructed to wash the site, soak the wart for up to 20 minutes, gently remove dead tissue with a pumice stone or emery board, and apply the solution or patch. Patches are usually changed every 48 hours. Liquid applications are usually used twice a day. You may need to repeat this process for several weeks to eliminate warts completely.
- Freezing (cryotherapy) products. Products that freeze plantar warts, such as Compound W Freeze Off or Dr. Scholl's Freeze Away Wart Remover, are available at drugstores without a prescription. Such products aren't as effective as cryotherapy done at the doctor's office because they don't freeze tissue at a temperature as low as that achieved with liquid nitrogen. The treatment may also result in some pain.
A number of alternative treatments have been promoted as effective interventions for warts, but there is little to no clinical evidence of the effectiveness of these treatments. Because many warts resolve on their own, it can be difficult without a well-designed study to determine if the disappearance of a wart is the result of the treatment or the natural course of the infection.
Alternative treatments include:
- Duct tape. "Duct tape therapy" has resulted in mixed results in a few clinical studies, but it may provide an effective low-cost option for some people. The treatment has generally included covering the wart with silver duct tape for six days, soaking the wart, gently removing dead tissue with a pumice stone or emery board, leaving the wart exposed for about 12 hours, and repeating the treatment until the wart is gone.
- Apple cider vinegar. Interventions with apple cider vinegar generally follow the following steps: soak the wart in apple cider vinegar for 20 minutes, gently remove dead tissue with a pumice stone or emery board, apply petroleum jelly around the wart to protect the skin, cover the wart with a cider-soaked piece of cotton ball, and cover the cotton ball with an adhesive bandage. The treatment is repeated until the wart falls off.
- Podophyllum. Podophyllum is a plant extract that may be sold under a number of names, including American mandrake, Himalayan mayapple and devil's apple. The extract applied as an ointment has toxic properties that may kill the infected skin cells. Podophyllum can cause pain and irritation. It shouldn't be used by pregnant or nursing mothers.
To reduce your risk of plantar warts:
- Avoid direct contact with warts. This includes your own warts.
- Keep your feet clean and dry. Change your shoes and socks daily.
- Don't go barefoot in public areas. Wear sandals or flip-flops in public pools and locker rooms.
- Don't pick at warts. Picking may spread the virus.
- Don't use the same file, pumice stone or nail clipper on your warts as you use on your healthy skin and nails.
- Wash your hands carefully after touching your warts.
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