Flat warts (Verruca plana) are a common skin condition resulting from infection with the Human Papillomavirus (HPV). These growths are generally harmless and are caused by specific, low-risk strains of the virus, primarily HPV types 3, 10, 28, and 49. Although flat warts often resolve on their own, sometimes taking months or even years, many people seek treatment for cosmetic concerns or if the warts become numerous or bothersome. This guide explores effective treatment options, ranging from over-the-counter methods to specialized professional therapies.
Distinct Characteristics of Flat Warts
Flat warts present with a specific appearance that differentiates them from other types of warts, like the rough, raised common wart. They are characterized by being slightly raised, smooth, and flat-topped papules, often described as having the size of a pinhead. These small lesions typically measure between 1 to 4 millimeters in diameter and can be flesh-colored, yellowish-brown, or pinkish.
They frequently appear in clusters, with a single affected area potentially harboring 20 to 200 individual warts. The most common locations are areas prone to minor skin trauma, such as the face, neck, arms, and the backs of the hands, though they can also be found on the legs. A distinctive feature is their tendency to form in a straight line, a pattern called autoinoculation, which results from spreading the virus through scratching or shaving across the skin.
Over-the-Counter Treatment Options
The initial approach to managing flat warts often involves over-the-counter (OTC) treatments. The most widely used OTC treatment contains salicylic acid, a keratolytic agent that works by slowly dissolving the layer of skin infected by the HPV virus. These products are available in various formulations, including liquids, gels, and pads, typically containing up to a 17% solution.
For the best results, the affected area should be soaked in warm water before application, and any dead skin should be gently rubbed off to help the medication penetrate the tissue. Consistent, daily application is necessary, and it may take several weeks or months to see full results. OTC freezing kits, which use cold substances like dimethyl ether and propane to destroy the wart tissue, are also available. However, the lower temperature achieved with these consumer products is generally less effective for widespread flat warts compared to the liquid nitrogen used professionally.
Professional and Prescription Therapies
When over-the-counter methods prove ineffective or if the warts are extensive, professional and prescription-strength therapies are often necessary. Dermatologists frequently prescribe topical retinoids, such as Tretinoin, a vitamin A derivative that promotes the shedding of skin cells to reduce the wart’s appearance.
Another effective prescription option is Imiquimod cream, an immune response modifier that stimulates the local immune system to attack the HPV virus. The topical chemotherapy agent 5-fluorouracil (5-FU) is also used, which inhibits the growth of the infected cells and is often applied under occlusion for up to a month. Due to the potential for irritation, especially when applied to sensitive areas like the face, these prescription treatments must be supervised by a healthcare provider.
For faster resolution or resistant cases, in-office procedures are employed, beginning with cryotherapy, where a specialized device is used to apply liquid nitrogen to freeze and destroy the wart tissue. This professional-grade freezing is significantly colder and more effective than OTC kits, though multiple treatments are often required. Other procedures include electrocautery and curettage, which involves scraping away the wart and then burning the base with an electrical instrument to prevent recurrence. Additionally, pulsed dye laser therapy can be used to destroy the tiny blood vessels that feed the wart, causing the tissue to die.
Preventing Spread and Recurrence
Preventing the spread of flat warts, both to other people and to new areas on one’s own body (autoinoculation), is essential. The HPV virus enters the skin through tiny cuts or abrasions, so avoiding trauma to the skin is important. People should refrain from picking, rubbing, or scratching the warts, as this can easily transfer the virus.
For those who shave, avoid shaving directly over the affected areas, as a razor can spread the viral particles across a wider skin surface. Maintaining good hand hygiene by washing hands frequently, especially after touching warts, helps limit transmission. Not sharing personal items like towels or razors and wearing footwear in public wet areas like locker rooms and pools can reduce the risk of contracting or spreading the virus.