A wart (also known as verruca) is generally a small, rough tumor, typically on hands and feet but often other locations, that can resemble a cauliflower or a solid blister. Warts are common, and are caused by a viral infection, specifically by the human papillomavirus (HPV) and are contagious when in contact with the skin of an infected person. It is also possible to get warts from using towels or other objects. They typically disappear after a few months but can last for years and can recur.
Types of wart
A range of different types of wart has been identified, varying in shape and site affected, as well as the type of human papillomavirus involved. These include
- common wart (Verruca vulgaris), a raised wart with roughened surface, most common on hands and knees;
- flat wart (Verruca plana), a small, smooth flattened wart, tan or flesh coloured, which can occur in large numbers; most common on the face, neck, hands, wrists and knees;
- filiform or digitate wart, a thread- or finger-like wart, most common on the face, especially near the eyelids and lips;
- plantar wart (verruca, Verruca pedis), a hard sometimes painful lump, often with multiple black specks in the center; usually only found on pressure points on the soles of the feet;
- mosaic wart, a group of tightly clustered plantar-type warts, commonly on the hands or soles of the feet;
- genital wart (venereal wart, Condyloma acuminatum, Verruca acuminata), a wart that occurs on the genitalia.
Treatments that may be prescribed by a medical professional include
- Keratolysis, removal of dead surface skin cells usually using salicylic acid, blistering agents, immune system modifiers ("immunomodulators"), or formaldehyde, often with mechanical paring of the wart with a pumice stone, blade etc.;
- Cryosurgery, which involves freezing the wart (generally with liquid nitrogen), creating a blister between the wart and epidermal layer, after which the wart and surrounding dead skin falls off by itself;
- Surgical curettage of the wart;
- Laser treatment;
- Imiquimod, a topical cream that helps the body's immune system fight the wart virus by encouraging interferon production;
- Injection of Candida, mumps, or Trichophyton antigens at the site of the wart, which stimulate the body's immune system;
- Cantharidin, a chemical found naturally in many members of the beetle family Meloidae which causes dermal blistering.
The wart often regrows after the skin has healed.
One review of 52 clinical trials of various cutaneous wart treatments concluded that topical treatments containing salicylic acid were the best supported, with an average cure rate of 75% observed with salicylic acid compared with 48% for placebo in six placebo-controlled trials including a total of 376 participants. The reviewers also concluded that there was little evidence of a significant benefit of Cryotherapy over placebo or no treatment.
There are several over-the-counter
options. The most common ones involve salicylic acid
. These products are readily available at drugstores
. There are typically two types of products: adhesive pads treated with salicylic acid or a bottle of concentrated salicylic acid solution. Removing a wart with salicylic acid requires a strict regimen of cleaning the area, applying the acid, and removing the dead skin with a pumice
stone or emery board
. It may take up to 12 weeks to remove a wart.
Another over-the-counter product that can aid in wart removal is silver nitrate in the form of a caustic pencil, which is also available at drug stores. This method generally takes three to six daily treatments to be effective. The instructions must be followed to minimize staining of skin and clothing.
Duct tape occlusion therapy
Duct tape occlusion therapy (DTOT) involves placing a piece of duct tape
over the wart(s) for six days, followed by soaking the area in water and scraping it with a pumice stone
or emery board
. Evidence suggests that DTOT is more effective than cryotherapy
The study cited above had 9 patients lost to the follow-up from the original 61 patients entered. In contrast to the flaws (15% of subjects lost to the follow-up) and favorable results of the above study, a more stringent study of 103 children found no benefits from duct tape . The evaluators were blinded during treatment for the most part, a placebo (corn pad) was used and there were no patients lost to the follow-up. After six weeks, rates of wart resolution were similar in the duct tape and corn pad groups and much lower than the rates seen in the earlier trial.
A similar trial comparing duct tape with a control treatment with a moleskin pad in 90 adults also found no difference in the rate of wart resolution at the end of two months (21 versus 22 percent) .