Understanding Warts

Warts are a painful, highly contagious and often difficult to manage skin infections that are regularly seen on the feet of patients of all ages and walks of life.

They are often referred to as verruca, plantar warts and papillomas and are frequently mistaken for other conditions such as corns or calluses which are caused by friction. Warts are in fact are caused by a viral infection from the Human Papilloma Virus (HPV). Science knows of about 120 different types of HPV but only about nine are known to infect the skin of the human foot.

Warts appear on the foot in two major variations, singular and mosaic, this being determined by the type of HPV that has infected the skin cells. It is accepted that small breaks in the skin’s outer layer (epidermis), usually caused by micro trauma, allow the virus to invade the cell nucleus of those cells that make our skin and effectively hijack their DNA. These cells then stop producing normal skin and make what we see as “wart tissue”.

Both forms of warts are painful, both forms spread and both forms are contagious. Singular warts however tend to more painful when they override weight-bearing areas on the sole of the foot. Children, especially teenagers, tend to be more susceptible to warts than adults whilst some people seem to be immune to the virus. It is thought that a combination of softer skin that breaks more easily combined with children’s greater exposure to places where this type of virus will spread such as swimming pools, locker rooms, school camps and shared showering facilities make this so.

Singular plantar warts are usually an orderly shape, circular or ovoid, with a well demarcated edge whilst the mosaic variety vary dramatically depending on the number of separate warts that exist inside the conglomerate. It is not unusual for a mosaic wart to have 150-200 separate warts within its boundary. Skin lines will always cease at the edge of a wart. Small black pinpoints often appear in the central mass of the wart, these represent strangled or thrombosed capillaries and not the roots of the wart. Singular plantar warts always produce pain when subjected to lateral or side-side finger pressure, unlike corns which are more irritated with direct pressure.

Warts of all varieties are too often left untreated. A single wart can grow to a size of 15-20 mm or more in a relatively short period time. The most common reasons for this are misdiagnosis and poor management.


Treatment regimens for warts have varied hugely over the past century. In the early 20th century thistle milk, salt and onions and even the first spit of the morning were applied to hopefully kill off a wart. In more recent times duct tape, banana skins and “the eye” of an Idaho potato have been employed with hope for the same outcome.

More recently treatments have followed a more scientific rationale. Most commonly topical acid preparations, or keratolytics, and those of the freezing variety such as carbon dioxide gas or liquid nitrogen. Both are successful to a degree but the acids are messy and difficult for patients and parents of young children to do whilst keeping dry during bathing/swimming and playing sport. Liquid nitrogen is just plain painful!!!

In the past 20 years the Essendon Foot Clinic has been recognised by both its patients and Podiatric peers as one of the leading clinics in the state of Victoria for managing all forms of simple and recalcitrant verruca, primarily because of the wide range of treatment variations it has on offer, some that are used at very few other podiatry clinics. These include;

  • Keratolytics – acid treatments that break down the tissues within, around and under the lesions creating a chemical burn to promote an immune reaction and leading to the demise of the verruca. Some interruption to activity is a downside to this treatment.
  • Cantharone – also known as “beetle juice” the solution utilises a substance known as canthardin, which is secreted by a beetle native to Central America, to choke the verruca by cutting off its blood supply. The canthardin dries up the blood vessels within the wart over a 72 hour period following application. Whilst some mild discomfort can be experienced by a small number of patients in the 24-48 hour period following the treatment, the application is totally painless making it ideal for infants and school aged children. It is however used on patients of all ages and boasts a success rate of over 90%. Most treatments involve only two consultations. Work, school and sport, including swimming, is not affected with this treatment.
  • DNCB – Dinitrochlorobenzene is an irritant applied to mosaic or large singular verruca that have proved recalcitrant to other forms of treatment. A sensitization of a 2% solution of DNCB on the forearm results in a modest skin reaction 14-21 days after application. Once this has occurred patient are supplied with a 0.2% DNCB solution to apply to the lesion(s) on a 1-2x daily basis for 3-6 months. The treatment does not interfere with any normal work or sporting activity.
  • Laser – click here to see the dedicated page to verruca management with laser.
  • Falknor’s Needling – The wart is anaesthetised and then a small needle is passed through the wart tissue with the aim of breaking the barrier between the virus and your immune system.
  • Oral Zinc – The use of oral Zinc supplementation has been shown to be effective in the management of recalcitrant warts. Speak with the Podiatrist’s at Essendon Foot Clinic to discuss a treatment regime that will be appropriate for you.