Plantar warts are small growths that usually appear on the heels or other weight-bearing areas of your feet. This pressure may also cause plantar warts to grow inward beneath a hard, thick layer of skin (callus).

Plantar warts are caused by 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 usually go away without treatment eventually. You may want to try self-care treatments or see your doctor to have the warts removed.

Plantar wart signs and symptoms include:

• A small, fleshy, rough, grainy growth (lesion) on the bottom of your foot, usually the base of the toes and forefoot or the heel
• 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 bleeding, 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
• 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 HPV in the outer layer of skin on the soles of your feet. They develop when the virus enters your body through tiny cuts, breaks or other weak spots on the bottoms of your feet.

HPV is very common, and more than 100 kinds of the virus exist. But only a few of them cause warts on the 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.

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 locker rooms

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.

To reduce your risk of plantar warts:

• Avoid direct contact with warts. This includes your own warts. Wash your hands carefully after touching a wart.
• Keep your feet clean and dry. Change your shoes and socks daily.
• Avoid walking barefoot around swimming pools and locker rooms.
• Don't pick at or scratch warts.
• Don't use the same emery board, pumice stone or nail clipper on your warts as you use on your healthy skin and nails.

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 are harmless and 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 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 office visits.

• Freezing medicine (cryotherapy). Cryotherapy done at a doctor's office involves applying liquid nitrogen to the wart, either with a spray or a cotton swab. This method can be painful, so your doctor may numb the area first.

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

  Some studies suggest that cryotherapy combined with salicylic acid treatment is more effective than just cryotherapy, but further study is needed.

Surgical or other procedures

If salicylic acid and freezing medicine 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 trichloroacetic acid 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 has a risk of scarring, this method usually isn't used to treat plantar warts unless other treatments have failed.
• Laser treatment. Pulsed-dye laser treatment burns closed (cauterizes) tiny blood vessels. The infected tissue eventually dies, and the wart falls off. This method requires repeat treatments every three to four weeks. The evidence for the effectiveness of this method is limited, and it can cause pain and potentially scarring.
• Vaccine. HPV vaccine has been used with success to treat warts even though this vaccine is not specifically targeted toward the wart virus that causes the majority of plantar warts.

Many people have removed warts with these self-care tips:

• 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 in warm water, and gently remove the top layer of softened skin with a pumice stone or emery board. Then after the skin has dried, you apply the solution or patch. Patches are usually changed every 24 to 48 hours. Liquid applications are generally used daily. You may need repeated applications on a regular basis over several weeks to months to see results.
• Freezing medicine (cryotherapy). Nonprescription medicines that freeze the wart include Compound W Freeze Off and 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. Using duct tape to remove warts is a harmless but unproven approach. To try it, cover the wart with silver duct tape, changing it every few days. Between applications, soak the wart and gently remove dead tissue with a pumice stone or emery board. Then leave the wart open to the air to dry for a few hours before covering it with tape again.

You'll likely start by seeing your primary care doctor. He or she may refer you 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 I start with at-home care?
• If I proceed with home treatment, 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 swimming pool or locker room — 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.