(Also Called 'Flat Warts')
What are warts?
Warts are an infection of the skin caused by the human papillomavirus (HPV). The virus enters the body through a break in the skin (such as a cut) and then forms a rough bump on the surface of the skin. Warts are benign (non-cancerous) growths.
Anyone can get warts, but they are more common among children because they frequently have scrapes and cuts. The elderly also get warts more frequently because they have a weaker immune system.
Warts are very contagious. They can easily be transmitted from one person to another by coming into direct contact with a wart or with something – such as a locker room floor or a towel – that has been in contact with a wart.
What are plantar warts?
A plantar wart is a wart that occurs on the sole (plantar) of the foot, most often on the parts of the sole that receive pressure when standing or walking. Because of this pressure, plantar warts are often flat or grow inward. Plantar warts can appear alone or in a cluster (mosaic warts).
Plantar warts are usually small. They tend to grow slowly and can eventually penetrate deep enough into the skin to cause discomfort or pain.
What are the symptoms of plantar warts?
People who get plantar warts may feel as if they have a stone in their shoe. Because of their flat appearance and location on the bottom of the foot, plantar warts are frequently mistaken for calluses. Like calluses, plantar warts have tough, thick skin. However, unlike calluses, a plantar wart is painful when squeezed. A plantar wart may also have black dots on its surface. These dots are from the dilated blood vessels in the wart.
How are plantar warts diagnosed?
The doctor will diagnose a plantar wart by examining the foot and the wart and noting any symptoms the patient may have.
How are plantar warts treated?
Plantar warts often go away on their own after a certain amount of time. However, since these warts are frequently painful, the patient may want to have them treated right away. In order to successfully treat a plantar wart and reduce the chances of it coming back, it must be removed completely.
Plantar warts can be treated at home or by a doctor:
- Salicylic acid: Salicylic acid is an over-the-counter product that comes in a gel or liquid, or as a patch. Salicylic acid is applied to the plantar wart every day, after soaking the foot to soften the wart. It can take several weeks for full results to be seen. Salicylic acid treatment does not cause pain.
- Duct tape: Another home remedy is duct tape. The tape is applied directly over the wart and left there for six days. Between treatments, the dead layers of the wart are filed down. However, because plantar warts often go away on their own, it is not clear if the duct tape actually works or simply coincides with the wart disappearing.
It is important that you not try to physically remove the wart yourself. Doing so can lead to infection or injury to the area.
There are several approaches the doctor may choose from to treat the wart. Treatment is done on an outpatient basis, meaning the patient goes home the day of the treatment.
Medical treatment options include:
- Topical treatments: The most common topical (applied to the skin) treatment for plantar warts is cantharidin, a substance that comes from an insect, the blister beetle. It is often used in combination with salicylic acid. The doctor applies the liquid combination of cantharidin and salicylic acid directly to the wart and then covers it with a bandage. Within a week or so a blister forms – which can cause some pain – under the wart. When the blister peels off, all or part of the wart peels off, as well. Multiple treatments may be required.
- Cryotherapy: This treatment destroys the wart by freezing it with liquid nitrogen. Similarly to the cantharidin, cryotherapy causes a blister to be formed. When the blister peels off, all or part of the wart peels off, as well. This treatment option is usually not used in very young children because it can be painful. Cryotherapy may require several sessions in order to be effective.
- Chemical peel: Chemical peels strip away layers of the wart. However, when the doctor chooses a chemical peel as a treatment, he or she will prescribe a more powerful concentration of a medication such as salicylic acid for you to apply at home.
- Other: Other options to treat plantar warts include laser therapy, surgery, and immunotherapy, an approach in which the doctor uses the patient’s immune system to destroy a plantar wart that is not responding to other treatments. However, because these treatments can be painful and cause scarring and other side effects, they are used less frequently.
Can plantar warts be prevented?
There is no foolproof way to prevent plantar warts. However, there are steps you can take to reduce your risk of getting them. HPV thrives in warm and humid areas. In order to reduce the risk of getting plantar warts, it is important to:
- wear flip flops or sandals when you use a public locker room, public pool area, or public showers;
- not touch or come in contact with another person’s wart;
- not scratch or pick at the wart;
- keep items such as clothing and towels that may come into contact with the wart away from others in the house.
Can plantar warts come back after being treated?
There is no practical way to keep plantar warts or any other types of warts from occurring again. A plantar wart may reappear near the location of the one that was treated, may show up on another part of the sole, or may never occur again.
Mulhem E, Pinelis S., Treatment of nongenital cutaneous warts. Am Fam Physician. 2011 Aug 1;84(3):288-293.
American College of Foot and Ankle Surgeons (ACFAS). Plantar wart (verruca plantaris). Accessed 2/24/2016.
Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr.. Chapter 134. Plantar Warts. In: Usatine RP, Smith MA, Chumley HS, Mayeaux EJ, Jr. eds. The Color Atlas of Family Medicine, 2e. New York, NY: McGraw-Hill; 2013.
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