Plantar Wart Triggers and How to Treat Them

Plantar warts form on the bottom of the foot. This part of your foot is called the plantar surface. The growths appear on the top layer of skin called the epidermis. They are caused by the human papillomavirus (HPV).

A plantar wart can spread if you touch, scratch, or pick at it. Sometimes, they form clusters on one or both feet. Plantar warts can go away suddenly after months or years.

This article will cover what causes plantar warts, how they are treated, and ways to prevent them.

What Are Plantar Warts?

Plantar warts are growths on the foot that are caused by HPV.

Several plantar warts may appear in a group. It's also possible to have one wart at first but more form over time.

Plantar warts have grainy, finger-like fibers with a hardened callus. If a plantar wart is trimmed back, you'll see some black dots. These dots are capillaries that have hardened, making them bigger.

Anyone can get a plantar wart, but it is most common in children, teens, and adults.

Plantar Warts vs. Corns

Plantar warts look like corns, but they have some key differences. Plantar warts have a different structure than corns. They also form in different places on the foot.

Corns are commonly found on the top surfaces of the small toes, especially over a joint. Plantar warts are more likely to pop up on the heel or weight-bearing parts of the bottom of the feet (the soles).

Plantar Wart Symptoms

Plantar warts may not hurt. However, if a wart presses on sensitive tissue and nerve endings in the foot, it can cause pain.

Plantar warts usually grow inward because when you walk or stand, it puts pressure on them. Warts growing inward and warts on the skin folds of the toes tend to hurt the most.

More prominent plantar warts can split open. When the sensitive tissue underneath gets irritated, it can cause pain and bleeding.

Causes

All warts are caused by HPV. It's the same virus that causes genital warts. There are more than 100 strains of HPV, but the HPV-1 strain is the most common cause of plantar warts. However, HPV types 2, 4, 60, and 63 also cause plantar warts.

The HPV virus lives best on moist surfaces. The virus is easily spread through tiny breaks in the outer part of the epidermis called the stratum corneum.

Once they've been infected with HPV, the skin cells begin to multiply rapidly. As they build up, the cells form a wart.

However, a wart may not develop for several weeks or months after an infection occurs. Once the wart has appeared, the virus can move from the first overgrowth to nearby breaks in the skin.

Not everyone exposed to HPV will get a wart. It's more likely to happen to:

• People with weak immune systems
• Those who frequently walk barefoot on moist surfaces (like locker room floors)
• People who have sweaty feet

Diagnosis

Healthcare providers can usually tell if a skin growth on your foot is a plantar wart just by looking at it. If they're unsure, they can cut a piece of the growth off to look for the black dots inside that are a clue it's a plantar wart.

A provider can also take a skin scraping called a shave biopsy. The piece of tissue is sent to the lab, where it can be looked at more closely. If the growth is not a plantar wart, the biopsy can help your provider figure out what it is.

Growths on the feet could be the result of other conditions like molluscum contagiosum, squamous cell carcinoma, or a complication of tuberculosis called verrucosa cutis.

Treatment

Smaller growths may go away on their own without treatment. Some warts can be treated at home with an over-the-counter (OTC) product.

Bigger or more painful warts may need medical treatment. The two most common ways to treat a plantar wart are freezing it off (cryotherapy) or cutting it out (surgical excision).

If a plantar wart is small and not bothering you, you can probably manage it on your own. However, you should always see your provider if:

• The wart is bleeding.
• It is making it hard for you to walk.
• The wart starts to feel or look different.
• It gets worse after treatment.

If you have diabetes, paying close attention to your feet is even more vital. Even a small wart can trigger neuropathic pain or lead to a diabetic foot infection.

Home Remedies

How well over-the-counter (OTC) treatments work depends on the size of the wart and how well you stick to doing the treatment. A larger wart is less likely to go away with OTC treatments alone.

Most OTC wart treatments contain an ingredient called salicylic acid. This substance is good at getting the skin to shed dead cells.

There are a few different kinds of OTC wart products, such as:

• Liquids you put on your skin with a dropper or swab
• Adhesive bandages that cover the wart
• Aerosol sprays that "freeze" and kill the tissue

Debriding Foot Skin

If you're using a product with salicylic acid, it will help eliminate the dead skin cells between treatments. This is called debridement. You can use a callus file or pumice stone to debride the skin.

Try not to be too aggressive when you are debriding. If you're too rough, it can cause bleeding, pain, or a boil or abscess.

Always clean your skin, hands, and any tools you use very well when you're done.

Prescriptions

When a wart doesn't get better from OTC treatment, it's called a recalcitrant wart. If you have a wart that hasn't gone away with at-home treatment, you might need a prescription.

Your provider may have you try a prescription-strength salicylic formulation to apply at home. It's similar to the OTC treatments, just stronger.

5% 5-FU Cream

Recalcitrant warts can also be treated with a topical 5% 5-fluorouracil (5-FU) cream. Your provider will write you a prescription for this medication.

The cream is typically put on twice a day. Your provider will tell you how long you need to use it. The treatment can cause mild redness, peeling, and a burning sensation when you put it on.

Research has shown that 5-FU cream can effectively treat warts, with almost 87% of patients experiencing cleared plantar warts in one study.

Is 5% 5-FU Approved to Treat Warts?

Currently, 5% 5-FU cream is approved to treat solar keratosis and a type of skin cancer called basal cell carcinoma. It's not approved to treat warts.

However, providers can still prescribe 5% 5-FU cream "off-label" to treat warts. Therefore, you should only use the cream for a wart if it's given to you by a dermatologist.

Medical Procedures

If you've tried OTC and prescription treatments, but they haven't worked, you might need to have the wart taken off by a provider.

There are a few procedures that can be used to remove plantar warts:

• Cryotherapy uses liquid nitrogen to freeze and kill the affected tissue. It's generally safe when performed by a healthcare provider, but you might need to have it done more than once.
• Trichloroacetic acid is a strong acid that needs to be applied by a provider. It might take several treatments for the wart to go away.
• Pulsed-dye laser therapy burns a wart. This process is called cauterization. You may have a lot of pain after the procedure. To ensure the wart goes away, you might need to have it done several times over three to four weeks.
• Electrosurgery and curettage involves an electric device that the provider uses to burn the cells. Then, a tool called a curette is used to scrape them off. Your foot will be numbed with a local anesthetic so you won't feel pain during the procedure. However, it might be very painful after the anesthetic has worn off.
• Bleomycin is a chemotherapy drug. The medication can be used off-label with electrosurgery to treat recalcitrant plantar warts. A small study in 2017 reported that an injection of bleomycin in the foot combined with electrosurgery led to 78% of warts going away. When only bleomycin was used, only 16% of warts went away.
• Surgery can also be done to remove warts. After you are given a local anesthetic, a provider uses a scalpel to cut the wart out of your foot. You usually need to have stitches to close the hole. After surgery, you might need to stay off your foot for a few days. This will help prevent infection and keep the wound from opening.
• Cantharidin is a substance that causes blisters to form. If injected under a wart, the blister pushes the wart up until it's separate from the skin, dries up, and falls off. Cantharidin is not approved for use in the United States.
• Immunotherapy uses medications like diphencyprone (DPCP) to eliminate HPV infection. It is usually only used for severe cases of plantar warts. Some people have an allergic reaction to immunotherapy, which could be life-threatening.

Prevention

While there are vaccines to prevent genital warts caused by HPV, these vaccines won't prevent plantar warts. The Gardasil, Gardasil 9, and Cervarix vaccines don't target the strains of HPV that cause plantar warts.

However, you can still take steps to prevent plantar warts:

• Keep your feet clean. Wash and dry your feet well. You can also use a little talcum powder to help absorb moisture and sweat.
• Cover your feet when you're walking in places where people go barefoot.
• If you get pedicures, ensure the salon you visit is clean (for example, sanitizing basins and tub liners). You might want to bring your own tools to the salon to help prevent infection.
• If you get a wart, change your shoes and socks regularly. This will help keep the virus from spreading.

Summary

Plantar warts are caused by HPV. They usually appear on the bottom of the feet and are easily spread. You may have a single wart of a group of them.

Plantar warts may not hurt. However, they can be painful if they're on a sensitive part of the foot. In some cases, they may make it hard to walk.

There are over-the-counter and prescription treatments for plantar warts, though they might need to be done several times to work. Plantar warts can be prevented with good foot hygiene.