Medical Edge Newspaper Column

Immunity May Be the Key To Shedding Warts For Good

April 17, 2008
Dear Mayo Clinic:
I'd like to know how to treat and get rid of small warts on my feet and hands. My family physician has burned off several over the past year. But I keep getting more, especially on top of my feet and ankles. Over the counter treatments like Compound W, don't seem to help. Any solutions?

Answer:
Warts are usually harmless and often disappear on their own, but they can be bothersome and embarrassing. Common warts are benign growths caused by a virus in the human papillomavirus (HPV) family. The virus causes the cells of the outer layer of the skin (the epidermis) to reproduce rapidly, creating a wart.

Our body's immune response is often responsible for eliminating warts. The immune system attacks and destroys most virus infections. However, as this immune system functions primarily in the dermis, the layer of skin just beneath the epidermis where the wart grows, it may take some time before it discovers the infection and mounts a response that will shed the wart virus and the wart.

Some wart treatments destroy the virus-infected cells. Such treatments include freezing warts with liquid nitrogen (cryosurgery) or burning them with electric current (electrodesiccation) or lasers. Unfortunately, if your body hasn't built up an immunity to the virus, then any leftover viruses can start another infection and the wart will recur.

In some instances, freezing the wart or irritating it with a salicylic acid treatment (found in over-the-counter products such as Compound W) releases the virus from the cell and jump-starts the body's immune response. It begins to react to the virus. Each treatment may act like a booster shot for your immune system. This is why freezing a wart several times may rid the body of the wart even though freezing it once did not.

A prescription cream containing the drug imiquimod may help activate the body's immune response. However, while it works well on genital warts and warts on mucous membranes where the skin is thin, the imiquimod molecule can not penetrate into common warts on the thicker skin of the hands and feet. There is also a wart vaccine to help prevent genital wart infections, but it doesn't seem to immunize enough to cause warts already there or in other areas to disappear.

Dermatologists have many treatment options for warts. In addition to freezing and burning them off, therapies include application of certain acids and chemicals, scraping (curettage) or removing the wart surgically. For warts that don't respond to standard treatments, a dermatologist may prescribe topical applications of retinoids (derived from vitamin A) or applications of chemotherapy drugs, or inject medication under the warts.

None of these therapies guarantees a cure. Warts on the soles of feet are especially pesky. If you're susceptible to the wart virus, new warts may crop up even after successful treatment. But don't give up hope. In such instances, more than one treatment or more than one approach to treatment may be necessary to manage the problem. I'd suggest you discuss treatment options with a dermatologist. Such options may include applying Compound W (or similar product) more often, or for longer periods of time, or covering the warts with duct tape or wart plasters.

— Mark Dahl, M.D., Dermatology, Mayo Clinic, Scottsdale, Ariz.