Also called verrucas, warts are small benign (non-cancerous) fleshy growth on the skin. They can grow almost anywhere on the body, but are usually seen on the hands, fingers, face, and feet. They are common and affect most people at some point in their lives.
CausesWarts are caused by infection of the outer layer of skin with a virus called the human papillomavirus (HPV). There are many different strains of HPV, which accounts for the different types of warts and their location on the body.
Infection occurs through breaks in the skin, such as a hangnail (a piece of partially disconnected skin of the cuticle or nail fold), cuts, or scratches. Biting one’s nails or nibbling the skin around fingernails can cause warts to spread on fingertips and around nails.
Warts are more common in children and adolescents because their immune systems may not yet have developed immunity to the virus. Warts may also occur in people with eczema (due to a broken skin barrier) and people whose immune system is suppressed due to treatment with certain medications or weakened due to HIV/AIDS.
Warts are contagious because the virus can be spread to other people by direct skin-to-skin contact or indirectly via shared objects, such as towels or washcloths. The virus can also be spread by self-inoculation, which occurs when a person scratches or picks a wart and the viruses that are released are spread to another area of skin.
Some strains of HPV are spread through sexual contact and cause genital warts and potentially cervical cancer. Genital warts are a sexually-transmitted disease.
Signs and symptoms
The different types of warts are mainly determined by where they grow on the body and their appearance. Signs and symptoms of different types of warts are as follows:
Common warts (verruca vulgaris):
- Flesh-coloured, white, pink, or tan.
- Irregularly shaped and dome-like with a grainy surface.
- Usually grow on the fingers, especially around the nails, and on the backs of hands.
- Feel rough to the touch.
- Often feature tiny black dots, which are small clotted blood vessels.
Foot warts (also called plantar warts):
- Grow on the soles (plantar surface) of the feet.
- Are often flat or grow inward (due to the pressure of standing and walking).
- Can grow in clusters.
- Can be painful.
- Can feature tiny black dots.
Flat or plane warts (verruca plana):
- Small, flat surface, slightly elevated, smooth, tan or flesh-coloured.
- Can grow anywhere but usually grow on the face in children, on the beard area in men, and on the legs in women.
- Tend to grow in large numbers.
Filiform warts (digitate warts):
- Appear as long threads or finger-like projections.
- Usually grow on the face (around the mouth, eyes, and nose).
DiagnosisWarts can usually be diagnosed on the basis of their appearance with diagnostic tests seldom being required.
Physical examination might include scraping off the top layer of the wart to check for signs of the tiny dark dots (the clotted blood vessels) that are characteristic of common warts.
Examination of a wart using a dermatoscope (a device comprised of a magnifying lens and a powerful lighting system) can be helpful in distinguishing viral warts from other types of skin growths, such as a skin cancer . Removing a small section of a wart (skin or shave biopsy) and sending it to a laboratory for analysis may also be used to exclude other types of skin growth.
Most people don’t bother seeking treatment because their warts are small and generally don’t cause problems. However, many people have their warts removed if they become painful, annoying, or embarrassing. You should see a GP if you have a wart that:
- Hurts, itches, burns, bleeds, or changes its appearance.
- Becomes bothersome and interferes with activities.
- Persists, spreads, or recurs, despite self-treatment.
- Is on your genitals.
You should also see a GP if you suspect that the growth is not a wart or you are an adult and warts have appeared in clusters (as this may indicate a weakening immune system).
In some cases, your GP might refer you to a dermatologist (skin specialist).
The aims of treatment are to destroy the wart and/or stimulate the body’s immune system response against the virus. Treatment may take weeks or months. However, no treatment is completely effective and warts can recur or spread. Warts tend to be more persistent in adults than in children and are more likely to recur in people whose immune system is weak or supressed.
Topical treatment (wart paints or gels)
Prescription-strength wart paints or gels containing salicylic acid are available for home treatment of common warts and plantar warts. Salicylic acid is a type of chemical peel that works by removing layers of a wart a little bit at a time. This requires daily application. Weaker-strength wart paints and gels are available without a prescription from pharmacies. Chemical peels don’t always work and can cause burning and stinging.
Other prescription-only topical treatments for warts include retinoids (e.g. tretinoin cream, adapalene gel), fluorouracil cream (which is toxic to living cells), and imiquimod (an immune system modulator), and diphencyprone (an immune system stimulator).
Cryotherapy performed in a GP clinic involves freezing the wart by applying liquid nitrogen, which is extremely cold (-196 °C). Freezing causes a blister to form under the wart, with the dead tissue usually falling off within a week to two. Repeat treatments may be needed. Liquid nitrogen cryotherapy can feel uncomfortable and might leave a white mark or scar.
Wart freezing products (e.g. DMEP aerosol spray, which is a mixture of dimethyl ether and propane) are available without a prescription for home treatment of common warts and plantar warts. The effectiveness of these products is unclear.
Electrosurgery (curettage and cautery)
Electrosurgery works by using a high-energy current to generate heat and burn (cauterise) the wart. Curettage involves scraping off (curetting) the wart with a sharp knife before or after electrosurgery. Electrosurgery is usually performed by a dermatologist and is used for larger warts and warts that have not responded to other treatments. This treatment can leave a scar.
Laser treatment (pulsed dye laser)
Laser treatment is also usually performed by a dermatologist and reserved for larger warts and warts resistant to other treatments. Laser treatment works by using high-energy light to cauterise tiny blood vessels within the wart. Without a blood supply the treated tissue eventually dies and the wart falls off. Laser treatment can cause scarring.
The following recommendations can help to stop warts from spreading:
- Avoid direct contact with warts.
- Don’t scratch or pick a wart.
- Wash your hands after touching a wart.
- Don’t bite your nails or suck fingers that have warts on them.
- Cover warts with a plaster when swimming.
- Take care not to cut a wart when shaving or clipping areas that have warts.
- Don’t share towels, flannels, socks, or shoes.
- Change your socks daily if you have a plantar wart.
- Don’t walk barefoot in public places if you have a plantar wart.
HPV vaccines are available to prevent genital warts and cervical cancer and may result in clearance of non-genital warts in some people. In New Zealand, 12-year-old girls and boys are vaccinated against specific strains of HPV as part of the National Immunisation Schedule.
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Updated: January 2019