Plantar Warts

Warts are localized skin thickenings, and ‘plantar warts’ are the thickenings of the feet soles (the ‘plantar’ surface). They are also known as verrucas. 

An infection causes warts in the outer layer of the skin (epidermis) with a virus called the ‘human papillomavirus.’ There are many different strains of this virus, and plantar warts are usually due to just a few of these strains. The infection makes the skin over-grow and thicken, leading to benign (non-cancerous) skin growth (the wart).

Plantar warts are caught by contact with infected skin scales – for example, from the floors of public locker rooms, shower cubicles, and the areas around swimming pools. The virus is not highly contagious, and it is unclear why some people develop plantar warts while others do not.

The virus enters the skin through tiny breaks in the skin surface. Moistness and maceration of the skin on the feet probably make infection with the virus easier.

No.

In most cases, plantar warts cause no symptoms. Some plantar warts can be uncomfortable, mainly if they are present on a weight-bearing area. ‘Mosaic’ warts (see below) are usually painless.

Plantar warts can occur anywhere on the soles and toes and often affect the weight-bearing areas. They vary in size from just a few millimeters to more than one centimeter. They may have a rough surface that protrudes from the skin surface. Close inspection with a magnifying glass may reveal small black dots. An individual may have one or many verrucas, and can also have warts elsewhere on the body. The term ‘mosaic wart’ is used for tightly packed clusters of small plantar warts that resemble a mosaic.

The diagnosis is usually based on clinical appearance. Sometimes it can be challenging to tell a plantar wart from corn. Your doctor may need to pare down the area to find the black dots that confirm the diagnosis of a viral wart. No other investigations are usually needed. 

• Salicylic acid paints and gels: These are available in different strengths. Salicylic acid works by removing the outer dead layers of skin and triggering the immune system into clearing the virus. Before applying the paint, the feet should be soaked in warm water and thickened skin filed away with a pumice stone or emery board. 
• Cryotherapy. (See patient information leaflet on Cryotherapy). Freezing warts with liquid nitrogen (a freezing gas) may be available at your doctor’s surgery or podiatrist. Thick warts need to be shaved before freezing to allow the cold to get into the skin. Ideally, cryotherapy should be repeated every three to four weeks. It is painful and may cause blisters and burns, and because of this, it is not usually recommended in children. Several freezes may be needed to clear warts, and it does not always work. Using a salicylic acid preparation in between freezes may improve the effectiveness.
• Other approved topical treatments for plantar warts include formaldehyde gel, glutaraldehyde, and silver nitrate caustic pencils.
• Other preparations include topical dithranol, podophyllotoxin, 5- fluorouracil trichloroacetic acid, and bleomycin injections.
• Contact immunotherapy with chemical paint such as diphenycyprone causes an allergic skin reaction that may boost the body’s immune reaction against the wart virus.
• Surgical removal of warts is an option if topical treatments do not work.  

• Wear comfortable shoes, and do not share your shoes or socks with anyone else. Special pads to relieve pressure on plantar warts can be bought at a chemist. 
• Keep your feet clean and dry. Change your shoes and socks daily. 
• Do not go barefoot in public places. Plantar warts should be covered with waterproof plasters or rubber ‘verruca socks’ if you go swimming. 
• When treating the wart, dispose of any skin filings hygienically and do not use the emery board or hard skin removal tools elsewhere as this could spread the infection.
• Apply topical treatment regularly to get the maximum chance of cure.
• To avoid spreading viral warts to other parts of the skin (autoinoculation) do not pick or scratch plantar warts.
• Do not use the same pumice stone, nail file, or nail clippers for your warts and healthy skin and nails.