Warts are benign growths caused by human papillomavirus (HPV). The virus infects the superficial layers of the skin through small breaks in the skin barrier and triggers abnormal cell proliferation. They’re contagious — spread through direct contact or contact with contaminated surfaces — and most common in children and young adults, though they can develop at any age. They’re not medically serious, but they can be persistent, uncomfortable (particularly plantar warts on weight-bearing areas of the foot), and a source of significant self-consciousness when located on visible areas. And they don’t reliably resolve on their own in adults the way they often do in children.
Types of warts
Common warts (verruca vulgaris) appear most often on the hands and fingers as rough, raised, skin-colored growths with a cauliflower-like surface and small black dots (thrombosed capillaries) visible within.
Plantar warts occur on the soles of the feet, where weight-bearing pressure causes them to grow inward. They can be intensely painful with standing or walking and are often surrounded by thickened callus that can obscure their appearance.
Flat warts (verruca plana) are smooth, slightly raised, skin-colored or lightly pigmented lesions that tend to appear in clusters, often on the face, neck, and arms. They can spread easily by shaving and are sometimes numerous.
Filiform warts are narrow, finger-like projections most common on the face and neck. They grow quickly and can bleed easily.
Treatment options
Salicylic acid available over the counter works for some warts with very consistent, patient application over several weeks to months. It works by chemically removing the outer layers of the wart. Patient commitment is the limiting factor — it needs to be applied daily, the treated area kept occluded, and the dead tissue removed between applications.
Cryotherapy with liquid nitrogen is the most common in-office treatment. The rapid freezing creates a blister beneath the wart that separates the abnormal tissue from the dermis. Multiple sessions are usually needed — typically every three to four weeks. It’s quick, doesn’t require anesthetic for most warts, and is effective for most common and plantar warts.
Intralesional immunotherapy — injecting the wart with agents like Candida antigen or bleomycin — stimulates a local immune response that can clear resistant warts, including multiple warts simultaneously through a systemic immune effect. This is particularly useful for warts that have failed conventional treatment.
Cantharidin is a blistering agent applied in the office that is effective for many warts, well-tolerated because there’s no pain at application, and particularly useful for children.
Frequently asked questions
How many treatments will I need?
Most warts require multiple cryotherapy sessions. Three to six treatments spaced three to four weeks apart is typical, though resistant warts may require more. We reassess approach if a wart isn’t responding after an adequate course.
Can warts come back after treatment?
Yes. Treatment destroys the visible wart, but the virus can persist in surrounding skin tissue and seed a new wart near the treated area. This is particularly common with plantar warts. It’s not a treatment failure — it’s the nature of a viral infection in the skin.
Should I treat a wart that doesn’t bother me?
From a pure medical standpoint, benign warts that aren’t causing symptoms can be observed. The practical argument for treatment is that warts can spread — to other areas of the body and to other people — and the longer they’re present, the more established they tend to become. We discuss the options and let patients decide.