Plantar warts (verrucas)

Warts are caused by infection in the outer layer of the skin (epidermis) with a virus called the 'human papilloma virus' (HPV). There are over 150 strains of this virus, and plantar warts are usually due to just a few of these strains. Infection makes the skin over-grow and thicken, leading to a benign (non-cancerous) skin growth (wart).

Plantar warts can be caught by direct contact with infected skin scales – for example from the floors of public changing rooms, shower cubicles and the areas around swimming pools. They can also be spread by autoinoculation, which happens when the warts are transferred to surrounding skin through scratching and rubbing.

Are plantar warts hereditary?

No.

In most cases, plantar warts cause no symptoms. Some plantar warts can be uncomfortable, particularly if they are present on a weight-bearing area. 'Mosaic' warts (see below) are usually painless. This is in comparison with myrmecial warts, which tend to stick out from the skin surface and are generally more painful.

What do plantar warts look like?

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 millimetres to more than one centimetre. They may have a rough surface that protrudes from the skin surface. Close inspection with a magnifying glass may reveal small black dots which represent clotted small blood vessels. An individual may have one or many warts and can also have them elsewhere on the body. The term 'mosaic wart' is used for tightly packed clusters of small plantar warts that resemble a mosaic.

Image DermNetNZ.

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

Can plantar warts be cured?

There is no guaranteed cure, but some treatments can help to clear warts.  The best chance of cure is in young people who have not had their warts for very long. If you have an illness that affects your immunity or are taking immunosuppressant medication, treatment can be less successful. Most verrucas will clear with time and can be left untreated if not causing problems.  When deciding whether to treat plantar warts or not, the following should be considered:

• Warts usually resolve by themselves without leaving a blemish or scar.
• Successful treatment of a viral wart does not prevent further warts.
• Some warts can be very stubborn. Treatments do not always work and may be time-consuming.
• Treating plantar warts can be painful, especially when liquid nitrogen is used, and can occasionally cause a blister which, on the sole, can be very uncomfortable.

How can plantar warts be treated?

Most plantar warts can be managed with advice from your pharmacist and with use of over-the counter topical treatments. Sometimes treatments might need to be prescribed by your general practitioner. You should see your GP if

• The lesion is bleeding, painful or changes in appearance or interferes with your daily activities
• You are not sure of the diagnosis
• You have treated the wart, but it persists and starts spreading
• You have diabetes or poor sensation on your feet
• You have weakened immune system because of immune-suppressing medications, AIDS, or immune-deficiency disorder.

Treatment options include: