Current Concepts In Managing Plantar Warts
Treatments for verruca plantaris range from cryotherapy to topical immunomodulators to lasers. Offering insights from the literature as well as his clinical experience, this author weighs the efficacy of various options for treating the common presentation of lower extremity warts.
Warts are among the most common dermatologic conditions the podiatrist treats. Plantar warts, also known as verruca plantaris, are caused by the human papillomavirus (HPV), which is a double-stranded DNA virus. All papillomaviruses cause infections in the skin or mucus membranes. Since warts are viral infections, treatment can be challenging. Most podiatrists will voice a level of frustration when treating warts because of the lack of predictability of a given treatment plan. Moreover, recurrence or spreading of warts is not uncommon.
When a patient presents to the office with warts, I have a discussion about the degree of difficulty that we may have in rapidly resolving the wart(s). I explain to the patient that we are treating a skin infection caused by a virus that may be resistant to many of the common treatments that are available. I will generally discuss all of the different treatment options and give more detail on the particular treatments I provide. I tell my patients the reason there are so many treatment options is that nothing works great all of the time.
When one reviews the published literature on wart treatments, our clinical experiences corroborate with the overwhelming conclusion that there is no one “most effective” treatment for warts.
For simplicity, I will categorize the treatment techniques for review. For completeness sake, some of the techniques are historical or have fallen out of favor. These are not in any particular order of efficacy.
What You Should Know About Topical Keratolytics
Salicylic acid is the “workhorse” for most podiatrists and family practitioners. Salicylic acid comes in varying strengths from over-the-counter (OTC) preparations at 17% to physician-only manufactured preparations of 55%. Additionally, a pharmacist can compound higher strengths. Other keratolytics include urea, mono- and trichloroacetic acid and cantharidin (Canthacur, Paladin Laboratories).
Keratolytics are designed to peel off layers of skin. When using the medication on a wart, the wart will shrink in size over time until it is gone. Usually, one performs debridement of as much of the keratosis as possible, subsequently applies the medication and uses an occlusive dressing with moleskin or tape. Only a physician should administer the higher strength acid treatments and two-week treatments are typical to repeat the process until the lesion resolves. For OTC treatments, patients can perform daily application. Encourage debridement with an emery board or pumice stone to help reduce the bulk of the wart.
Cantharidin is derived from a beetle and is commonly referred to as beetle juice. Most of the cantharidin used in the United States is either purchased from Canada where it is manufactured or in the U.S. by a compounding pharmacy. Generally, the recipe includes cantharidin, podophyllum and salicylic acid.
The physician applies cantharidin to the wart and covers it with a Band-Aid or tape. The skin will develop a blistering reaction. The wart or part of the wart lifts off, usually within 12 hours. Multiple treatments may be necessary as is commonplace with all of the keratolytic treatment techniques.
A study by Becerro de Bengoa Vallejo and colleagues reported on the use of cantharidin in a retrospective study involving 144 patients.1 After six months of follow-up, 95.8 percent of patients experienced complete eradication of plantar warts.