Plantar warts are hard, grainy growths that usually appear on the heels or balls of your feet, areas that feel the most pressure. This pressure also may cause plantar warts to grow inward beneath a hard, thick layer of skin (callus).

Plantar warts are caused by the human papillomavirus (HPV). The virus enters your body through tiny cuts, breaks or other weak spots on the bottom of your feet.

Most plantar warts aren't a serious health concern and may not require treatment. But plantar warts can cause discomfort or pain. If self-care treatments for plantar warts don't work, you may want to see your doctor to have them removed.

Plantar wart signs and symptoms include:

  • A small, fleshy, rough, grainy growth (lesion) on the bottom of your foot
  • Hard, thickened skin (callus) over a well-defined "spot" on the skin, where a wart has grown inward
  • Black pinpoints, which are commonly called wart seeds but are actually small, clotted blood vessels
  • A lesion that interrupts the normal lines and ridges in the skin of your foot
  • Pain or tenderness when walking or standing

When to see a doctor

See your doctor for the lesion on your foot if:

  • The lesion is painful or changes in appearance or color
  • You've tried treating the wart, but it persists, multiplies or recurs
  • Your discomfort interferes with activities
  • You also have diabetes or poor sensation in your feet — in which case, you'll need treatment supervised by a doctor
  • You also have a weakened immune system because of immune-suppressing drugs, HIV/AIDS or other immune system disorders
  • You aren't sure whether the lesion is a wart

Plantar warts are caused by an infection with the human papillomavirus (HPV) in the outer layer of skin on the soles of your feet.

More than 100 types of HPV exist, but only a few 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. Not everyone who comes in contact with it develops warts. Even people in the same family react to the virus differently.

The HPV strains that cause plantar warts aren't highly contagious. So the virus isn't easily transmitted by direct contact from one person to another. But it thrives in warm, moist environments. Consequently, you may contract the virus by walking barefoot around swimming pools or locker rooms. If the virus spreads from the first site of infection, more warts may appear.

The virus also needs to have a point of entry into the skin of the foot:

  • Cracks in dry skin
  • Cuts or scrapes
  • Wet, softened, fragile skin from being in the water a long time

Anyone can develop plantar warts, but this type of wart is more likely to affect:

  • Children and teenagers
  • People with weakened immune systems
  • People who have had plantar warts before
  • People who walk barefoot where exposure to a wart-causing virus is common, such as public showers

When plantar warts cause pain, you may alter your normal posture or gait — perhaps without realizing it. Eventually, this change in how you stand, walk or run can cause muscle or joint discomfort.

You'll likely start by seeing your primary care doctor. But you may be referred to a specialist in disorders of the skin (dermatologist) or feet (podiatrist). The following tips can help you prepare for your appointment.

What you can do

Bring a list of all medications you take regularly — including over-the-counter (nonprescription) medications and dietary supplements — and the daily dosage of each.

You may also want to list questions for your doctor, such as:

  • 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 do you need to do?
  • How long will it take to get results?
  • How can I prevent warts?

What to expect from your doctor

Your doctor may ask you questions such as:

  • When did the lesion first appear?
  • Has it changed in size or appearance?
  • Is your condition painful?
  • Have you had warts before?
  • Do you have diabetes or poor sensation in your feet?
  • Do you have any condition or take any medication that has weakened your ability to fight disease (immune response)?
  • Have you tried any home remedies? If so, how long have you used them and have they helped?
  • Do you use a public pool or locker room shower — places that can harbor wart-causing viruses?

What you can do in the meantime

If you're sure you have a plantar wart, you may try over-the-counter remedies or alternative medicine approaches. But talk with your doctor before trying self-care treatments if you have:

  • Diabetes
  • Poor sensation in your feet
  • Weakened immunity

If pressure on the wart causes pain, try wearing well-cushioned shoes, such as athletic shoes that evenly support the sole and relieve some of the pressure. Avoid wearing uncomfortable shoes.

In most cases, your doctor can diagnose a plantar wart with one or more of these techniques:

  • Examining the lesion
  • Paring the lesion with a scalpel and checking for signs of dark, pinpoint dots — tiny clotted blood vessels
  • Removing a small section of the lesion (shave biopsy) and sending it to a laboratory for analysis

Most plantar warts go away without treatment, though it may take a year or two. If your warts are painful or spreading, you may want to try treating them with over-the-counter (nonprescription) medications or home remedies. You may need many repeated treatments before the warts go away, and they may return later.

If your self-care approaches haven't helped, talk with your doctor about trying these treatments:

  • Stronger peeling medicine (salicylic acid). Prescription-strength wart medications with salicylic acid work by removing layers of a wart a little bit at a time. They may also stimulate your immune system's ability to fight the wart.

    Your doctor will likely suggest you apply the medicine regularly at home, followed by occasional visits to the doctor's office. Your doctor may pare away part of the wart or use freezing treatment (cryotherapy). Studies show that salicylic acid is more effective when combined with freezing.

  • Freezing medicine (cryotherapy). Freezing therapy done at a doctor's office involves applying liquid nitrogen to your wart, either with a spray or a cotton swab. Your doctor may numb the area first because it can be painful when the liquid nitrogen is applied.

    The chemical causes a blister to form around your wart, and the dead tissue sloughs off within a week or so. It may also stimulate your immune system to fight viral warts. Usually, you'll return to the doctor's office for repeat treatments every three to four weeks until the wart disappears.

    Some studies show that this treatment is more effective when combined with salicylic acid treatments.

Surgical or other procedures

If salicylic acid and freezing don't work, your doctor may recommend one or more of the following treatments:

  • Other acids. Your doctor shaves the surface of the wart and applies bichloracetic acid or trichloroacetic with a wooden toothpick. You'll need to return to the doctor's office for repeat treatments every week or so. Side effects include burning and stinging. Between visits, you may be asked to apply salicylic acid to the wart.
  • Immune therapy. This method uses medications or solutions to stimulate your immune system to fight viral warts. Your doctor may inject your warts with a foreign substance (antigen) or apply a solution or cream to the warts.
  • Minor surgery. Your doctor cuts away the wart or destroys it by using an electric needle (electrodesiccation and curettage). This procedure can be painful, so your doctor will numb your skin first. Because surgery can cause scarring, this method usually isn't used to treat plantar warts.
  • Laser treatment. Pulsed-dye laser treatment burns closed (cauterizes) tiny blood vessels. The infected tissue eventually dies, and the wart falls off. The evidence for the effectiveness of this method is limited, and it can cause pain and scarring.
  • Vaccine. Human papillomavirus (HPV) vaccine has been used with success to treat warts.

Many people have removed warts with:

  • Peeling medicine (salicylic acid). Nonprescription wart removal products are available as a patch or liquid. Usually, you're instructed to wash the site, soak it 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 generally used twice a day. You may not see results for several weeks.
  • Freezing medicine (cryotherapy). Nonprescription medicines that freeze the wart include Compound W Freeze Off or Dr. Scholl's Freeze Away. The Food and Drug Administration cautions that some wart removers are flammable and shouldn't be used around fire, flame, heat sources (such as curling irons) and lit cigarettes.
  • Duct tape. You use this by covering the wart with silver duct tape for six days, soaking the wart in water, gently removing dead tissue with a pumice stone or emery board, and then leaving the wart exposed for about 12 hours. You repeat the process until the wart is gone.

    Study results have been mixed on the effectiveness of duct tape in removing warts, either alone or with other therapies.

The following nontraditional treatments have worked for some people, but no evidence shows they're any better than salicylic acid and cryotherapy:

  • Zinc. This is available as an ointment you apply to the wart or as a pill. The oral form may be particularly effective in people with a zinc deficiency.
  • Silver nitrate. This is available as a solution or ointment you apply to the wart.
  • Smoke. Some people showed benefit from treating their wart in a "smoke box" with smoke from burnt leaves of a type of poplar tree called Populus euphratica.

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.
  • Wear shoes or sandals where it's common to be exposed to a wart-causing virus, such as around swimming pools or in gym showers.
  • Don't pick at warts. Picking may spread the virus.
  • Don't use the same emery board, pumice stone or nail clipper on your warts as you use on your healthy skin and nails.
  • Use a disposable emery board, to avoid spreading the virus.
  • Wash your hands carefully after touching your warts.
May 22, 2014