OTCs Today
Mary Warner
Warts, or verrucae, are a common skin disorder caused by HPV. Fortunately, warts are considered benign and often resolve without treatment within a few months to a year. However, many patients seek OTC treatment because of pain and cosmetic appearance or because of their concern about transmitting HPV to others. Self-treatment options include salicylic acid, freezing formulations, and duct tape.
Warts occur more frequently in children and adolescents than in infants and adults, with peak incidence among 12- to 16-year-old children. They can appear anywhere on the body but are most commonly found on the hands and feet. HPV can enter the epidermal layer through minor skin irritations and infect the basal keratinocytes, and the appearance, size, shape, and response to treatment of individual warts vary by HPV subtype and the specific location on the body.
Common warts are skin-colored or brown, hyperkeratotic, dome-shaped papules with a rough-looking, often cauliflower-textured surface and are usually painless. Plantar warts, callus-like lesions that occur on the feet, can be painful because they extend deeply into the epidermis and often occur in a weight-bearing location on the sole of the foot.
Salicylic acid
Salicylic acid is a keratolytic agent that is effective for common warts and plantar warts. It slowly destroys the virus-infected cells but may induce mild irritation. It’s important to note that FDA recommends that salicylic acid be used for self-treatment of common warts and plantar warts only because of the difficulty in identifying other types of warts without provider guidance. Products containing salicylic acid are readily available, have few adverse effects when used as directed, and are reasonably effective.
Salicylic acid products are more effective than placebo in treating warts on both the hands and the feet but have been shown to be more effective on the hands than on the feet. Salicylic acid concentrations of 17% are used for common warts, and higher concentrations (40%) are used for plantar warts. These products (Compound W, Dr. Scholl’s Clear Away, others) must be used daily, and in most instances, warts will begin to decrease in size within a couple of weeks of treatment. Self-treatment for both common warts and plantar warts should not continue past 12 weeks.
Cryotherapy
Cryotherapy with liquid nitrogen and other agents has been used for many years for wart removal in the office setting. FDA has approved a variety of nonprescription products that contain either nitrous oxide (NO) or a mixture of dimethyl ether and propane (DMEP) for self-treatment for common warts and plantar warts. Neither NO nor DMEP can reach temperatures as low as liquid nitrogen, but they do get cold enough to freeze the warts.
Nonprescription cryotherapy products are available in liquid or spray form (Compound W Freeze Off, Dr. Scholl’s Freeze Away, others) with each product having specific directions for preparing the applicator. The product is applied directly to the wart following the supplied directions carefully to avoid damaging the healthy skin around the wart. A blister will form under the wart, and if the treatment is effective, the wart will fall off after about 10 days. It’s important not to reuse cryotherapy applicators more than once to avoid reinfecting the tissue or spreading the virus to others.
In some cases, a single treatment will be effective for both common and plantar warts, but self-treatment can be repeated every 2 weeks as needed to a maximum of three sessions over no more than 12 weeks.
Duct tape
Recently, several small studies have shown that duct tape can be used to eliminate warts, with mixed effectiveness. Patients who would like to try this method can cover the wart with duct tape for 6 or 7 days, then soak the wart in water. After 12 hours of exposure to the air, the process is repeated until the wart is gone.
What to tell your patients
Ensure that patients understand that self-treatment doesn’t cure HPV infection. Plantar warts can be confused with corns, calluses, and malignant growths, and patients should see a podiatrist or other specialist if there is any question of what type of lesion is present. Patients should be advised that they can avoid development of warts by not going barefoot, especially on wet surfaces, and using public showers.
Advise patients that warts often recur after treatment and if salicylic acid treatment doesn’t completely resolve the wart after 12 weeks of treatment, patients should see a specialist provider for evaluation. Likewise, if three sessions of cryogenic treatment do not resolve the wart, patients should be referred for specialist evaluation. Recurrent or persistent warts may require a combination of treatments.
For more information on nonprescription treatment of warts, see Chapter 43 in APhA’s Handbook of Nonprescription Drugs, 21st edition, available through the bookstore at pharmacist.com, or visit APhA OTC on PharmacyLibrary. ■