Viral Warts

What is a viral wart?

A wart develops when human papillomavirus infects the basal layer of the epidermis, usually entering through a small break in the skin. The virus drives the skin cells to multiply and thicken, producing the characteristic hard, rough surface — and generating infectious virus particles within it.

The incubation period can be as long as twelve months, which is why it is usually impossible to say where or when a wart was acquired. It also explains why new warts sometimes appear after treatment has begun: they were already incubating.

A wart is a benign lesion. The great majority never cause anything worse than discomfort and inconvenience.

How warts are treated

The first question is not which treatment but whether to treat at all. Since many warts clear spontaneously, watchful waiting is entirely reasonable for a lesion that is not causing symptoms — particularly in children, in whom treatment can be distressing.

Treatment is generally chosen when warts are painful, multiplying, persistent, large, or affecting appearance and confidence.

Topical treatment

Salicylic acid has the most consistent evidence among topical options, and works by gradually removing the infected skin. The benefit is more apparent on the hands than on the feet. Soaking and gently filing the surface before application improves the response. It requires daily application over months — the most common reason it fails is stopping too early.

Cryotherapy

Freezing with liquid nitrogen is performed in the clinic, typically repeated every two to three weeks. More aggressive freezing is more effective but causes more pain and blistering, so the intensity is matched to the site and to the patient — it is often unsuitable for young children. Combining cryotherapy with salicylic acid appears more effective than salicylic acid alone.

Other approaches

• Paring — reducing the thickened surface, which makes other treatments work better
• Topical retinoids — an option for plane warts and warts on the face
• Curettage — sometimes used for a solitary wart, and allows the tissue to be examined if there is diagnostic doubt
• Laser treatment and contact immunotherapy — for resistant warts

When to see a dermatologist

Consider a specialist assessment if:

• There is any uncertainty about whether the lesion is a wart, particularly a single persistent lesion in an older adult
• Warts have not responded to a reasonable trial of treatment
• Warts are numerous, spreading, or recurring
• A plantar wart is painful enough to affect walking
• Warts are on the face, where self-treatment is not appropriate
• You are immunosuppressed — through medication, transplantation or illness
• A longstanding wart changes in size, colour or texture

Warts are diagnosed clinically in most cases. Where the diagnosis is uncertain, the lesion may be removed by curettage so the tissue can be examined under the microscope.