What are verrucae?
A verruca, also known as a plantar wart, is a small, rough growth of the skin that appears on the sole of the foot and toes, often protruding from the skin surface. Verrucae are benign (non-cancerous) growths. They can vary in size from a millimetre to more than a centimetre and can appear as distinct individual verrucae, or in clusters known as mosaic verruca. They sometimes appear with tiny black dots in them, which are due to clotted blood. Verrucae may cause pain, particularly if they form over weight-bearing areas of the foot. It can sometimes be difficult to tell the difference between a verruca and a corn.
What causes them?
Verrucae are caused by a viral infection in the outer layer of the skin by certain strains of the human papilloma virus (HPV). The skin barrier starts to break down when it gets very wet, creating tiny cracks through which the virus can enter. The virus causes the skin to overgrow and thicken, creating a wart. They can be contagious and spread through direct contact with another infected person or indirectly through contact with contaminated surfaces such as floors of communal showers and swimming pools.
Who gets verrucae?
Verrucae are most commonly found in school aged children, adolescents and young adults as well as people who use communal changing rooms, showers and pools.
What are the treatment options?
Treatment may not always be necessary if the verruca is not causing discomfort, and most verrucae will go away on their own with time. Although there are a range of treatment options available which can help to resolve verrucae, there is no guaranteed success, as most treatment options rely on creating localised skin damage and inflammation to make the immune system respond and clear the virus. The treatments listed below are not as exhaustive list, and the most suitable treatment method will depend on a number of factors. Young people who have not had the verruca for long have the best chance of cure. People with immunodeficiency or on immune suppressing medications will have less success with treatment.
No treatment: Left untreated, up to 65% of verrucae go away by themselves within two years.
Taping: Use of a skin safe tape such as zinc oxide tape traps moisture in the skin and can help make verrucae more comfortable by softening the hard skin that builds up.
Salicylic acid: There are a number of over the counter paints and gels containing varying concentrations of salicylic acid applied to the skin for treating verrucae, as well as higher concentrations available to Podiatrists. This works by removing the outer layers of dead skin and triggering the immune system to clear the virus. Care should be taken not to get the acid on the surrounding normal skin as it can cause damage and be painful. This can take many treatments for the verruca to resolve and can cause skin irritation. Salicylic acid treatments can have low success rates averaging around 50%, comparable to cryotherapy.
Cryotherapy: This involves freezing the verruca with liquid nitrogen and works by causing localised skin damage to trigger an immune response. Several treatments may be required and treatment can be painful and cause blisters and burns. Cryotherapy can have low success rates averaging around 50%, comparable to salicylic acid treatments.
Other topical treatments: There is a wide range of other treatments that are applied to the skin, including glutaraldehyde, silver nitrate and nitric-zinc complex solution. These all require multiple treatment applications until the verruca resolves.
Needling: Performed with local anaesthetic by a Podiatrist, needling uses a small needle to puncture the verruca multiple times to cause skin damage and introduce the virus into the deeper layers of the skin to trigger an immune response. Several treatment sessions may be needed and reported success rates are around 70% for this treatment.
SWIFT: Performed in clinic by a Podiatrist, this treatment uses microwaves focused on the verruca to rapidly heat and destroy skin cells, thus causing damage that triggers inflammation and an immune response. Several sessions may be required and it can be uncomfortable. Success rates have been reported at 76% after three treatment sessions and over 80% after 4 sessions.
Surgical removal: Carried out under local anaesthetic by a podiatric surgeon, a verruca may be cut out using a curette. There is still a chance of the verruca reoccurring even with surgical removal.
What can I do to prevent them?
There are a number of measures you can take to prevent verrucae and stop them spreading:
- Keep feet clean and dry
- Change socks daily
- Wear flip flops or sandals in communal showers or changing rooms and ensure that any verruca is covered with a waterproof plaster or verruca sock when swimming
- Keep any cuts or scratches on feet covered when using communal facilities
- Avoid sharing shoes, socks or towels
- Avoid direct contact with verrucae on other people
- Avoid picking at a verruca as this can spread it to other areas
- Wash your hands well after touching verrucae to prevent them spreading
- Avoid filing the skin over a verruca as this can cause it to spread
What happens if they are not treated properly?
Most verruca will clear on their own without treatment, however some can remain for decades. If left untreated they could cause pain, and improper management could lead to them spreading.
Cara Tucker 