Verrucas

A verruca (plantar wart) is a wart on the sole of the foot. It is the same as a common wart, but the weight of the body presses it into the foot, which can be painful.

Verrucas are slightly raised and circular in shape, with a thickened rim of surrounding skin. The surface may have black dots (‘pepper-pot’ appearance). There may be several verrucas or just one.

Sometimes verrucas form clusters of small warts, called ‘mosaic warts’ – these are usually painless. In children, verrucas tend to come and go quite quickly, but in adults they can persist for several years if they are not treated.

How verrucas spread

Like other warts, verrucas are caused by strains of papillomavirus. There is lots of papillomavirus around, and many people carry it on the surface of their skin. It does not cause any harm unless it penetrates into the skin, where it can take hold and cause a wart. This is most likely to happen if the surface of your skin is already damaged, with tiny cracks.

Most people believe that verrucas are caught in the changing rooms of swimming pools and the pool surrounds, but only one scientific study has shown that people who use swimming pools regularly are more likely to get verrucas. Other studies have shown no link.

There is probably plenty of papillomavirus around swimming pools, particularly in the shower area. However, you are very unlikely to get a verruca if your skin is undamaged. If you want to minimize the risk, wear flip-flops in the shower area.

What you might do

Decide whether it really is a verruca. They are easily confused with corns and calluses, which are thickened areas of skin caused by friction. Corns are often seen over hammer toes and where shoes press on the little toe, but they can occur on the sole of the foot just below the toes. Look closely at the verruca, using a mirror and a magnifying glass if possible. Corns and calluses have normal skin lines (like the lines used in fingerprints) over them, but the surface of a verruca is slightly lumpy without lines. If you are not sure, see a chiropodist or ask your doctor.

Do nothing. Just covering the verucca with a plaster and doing nothing might be the best option, for the following reasons.

• Without treatment, verrucas almost always disappear within 2 years. Some go within a month or two. Treatments are inconvenient and can be uncomfortable.
• It is possible that letting verrucas disappear naturally helps the body to build up immunity, making you less likely to have them in the future.
• Most treatments involve rubbing the wart with pumice or an emery board. Some experts think this helps the virus to spread into nearby skin.
• You do not need to worry too much about infecting other people in swimming pools and similar places, because the virus is probably already there.

Decide who should treat it. Decide whether you should treat the verruca yourself, or whether you should see a chiropodist. Do not try to treat it yourself if you have diabetes, or if you already have a skin problem such as eczema. Most chiropodists advise against do-it-yourself treatment, and prefer to be consulted when the verruca is small and easier for them to deal with.

Keep your feet as dry as possible. Papillomavirus can spread through wet, soggy skin to form a patch of mosaic warts.

Relieve the discomfort. Stick a ring-shaped foam pad round the verruca to take the pressure off it. You can buy these from pharmacists and they are sometimes labelled ‘for corns’.

Salicylic acid paint, gel or ‘verruca plasters’ can be bought from a pharmacist. Before using the paint or gel, soak your foot in warm water for 5 minutes, and then rub the surface of the verruca with a pumice stone. Do not overdo it. Carefully apply the paint and let it dry. Cover with a large sticking plaster. Repeat this treatment every evening until the verruca disappears, which may take 12 weeks. If it becomes painful, stop the treatment for a few days.

Verruca plasters are convenient. They are discs soaked in salicylic acid that you stick over the verruca and change every day. Some have built-in padding to deflect pressure from the verruca. Before applying the plaster, soak your foot and use pumice to rub some of the wart away. Put a piece of wide adhesive bandage over the plaster to make sure it stays in position.

Silver nitrate (caustic) pencil. If salicylic acid does not work, you can try a silver nitrate pencil. In the UK, you can buy this from pharmacies without a prescription. It gently burns the wart. Use it carefully according to the manufacturer’s instructions

A freezing aerosol is now available from pharmacies. It works in a similar way to the freezing treatment used by chiropodists and doctors, but does not reach the very low temperatures that their equipment achieves. Only one application is needed. Follow the manufacturer’s instructions carefully.

Try a herbal remedy from a health shop. It is difficult to know whether these are effective, because most have not been fully investigated in scientific trials. Tea tree oil, applied twice daily on its own or mixed with garlic juice, is said to have an effect. A tincture made from Chelidonium (the Greater Celandine) is said to be antiviral and to damage wart cells.

What you should never do

Do not try scraping it away with a corn knife. You could damage your skin and cause an infection. Also, the verucca will come back and others may occur nearby in the damaged skin.

What a chiropodist or your doctor can do

Chiropodists can check that you have a verruca and not some other problem, and they offer a range of treatments, including freezing (cryotherapy). Freezing tends to be less effective for verrucas than for common warts, and can be painful. It may be a good idea if you have mosaic warts, because these do not respond very well to salicylic acid. If you have a really troublesome verruca, your doctor might refer you to a hospital dermatology department for treatment.

Useful contacts

The American Academy of Dermatology has a warts fact sheet on its website.
www.aad.org/public/Publications/pamphlets/Warts.htm

Freezing aerosol. The Wartner aerosol is available from pharmacies. You can also buy it from several websites.
www.wartner.co.uk

The Society of Chiropodists and Podiatrists can help you find a state-registered chiropodist. Their website has information about verrucas and other foot problems, and has a ‘find a local chiropodist’ facility. Tel: 020 7234 8620.
www.feetforlife.org

The American Academy of Family Physicians has a detailed article about warts (intended for doctors) on its website.
www.aafp.org/afp/20050815/647.html