Verruca (plantar wart) - Causes, Treatment & When to See a Doctor

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What is Verruca (plantar wart)?

A verruca, more commonly called a plantar wart, is a small, rough growth that develops on the weight‑bearing areas of the foot, usually the heels or balls of the toes. It is caused by an infection of the skin with certain types of human papillomavirus (HPV). Unlike a typical skin blemish, a plantar wart grows inward because the pressure from walking pushes it into the deeper layers of the skin, creating a hard, callus‑like surface. Most people notice a tiny black dot in the centre of the wart – these are tiny clotted blood vessels that give the lesion its characteristic appearance.

Common Causes

Plantar warts are not caused by a single factor but result from a combination of viral exposure and skin conditions that allow the virus to enter. Below are the most frequent contributors:

• Human papillomavirus (HPV) infection: Types 1, 2, 4, and 63 are most often linked to plantar warts.
• Skin breaks or micro‑trauma: Cuts, splinters, or even tough calluses create entry points for the virus.
• Moist, warm environments: Public showers, locker rooms, swimming pools, and gym mats foster virus survival.
• Walking barefoot: Direct contact with contaminated surfaces increases risk.
• Weakened immune system: Conditions such as HIV, cancer, or immunosuppressive medications can make it easier for HPV to establish infection.
• Age: Children and teenagers are most susceptible; their immune systems are still maturing.
• Frequent foot sweat: Excess moisture softens the skin, making it more vulnerable.
• Existing foot conditions: Athlete’s foot, eczema, or other dermatologic issues disrupt the skin barrier.
• Family history: A genetic predisposition may affect how effectively the body fights HPV.
• Close contact with an infected person: Sharing socks, shoes, or towels can transfer the virus.

Associated Symptoms

While many plantar warts are painless, they can produce a range of additional signs:

• Small, grainy or rough surface that feels like a callus.
• Black pin‑point dots (tiny clotted blood vessels) in the centre.
• Localized pain or tenderness when pressure is applied—especially when standing or walking.
• Surrounding skin may become thickened or callused.
• Occasional itching or a burning sensation.
• Multiple warts clustered together, sometimes referred to as “mosaic” warts.
• Rarely, secondary bacterial infection causing redness, swelling, or pus.

When to See a Doctor

Most plantar warts resolve on their own within 2–3 years, but medical evaluation is recommended when any of the following occur:

• Severe or worsening pain that interferes with walking or daily activities.
• Rapid growth or spreading to several toes or the sole.
• Signs of infection – redness, warmth, swelling, or drainage of pus.
• Uncertainty about the diagnosis (e.g., could be a corn, melanoma, or foreign body).
• Underlying health conditions that weaken the immune system.
• Pregnancy – some treatments are contraindicated.
• Persistent warts after 12–18 months of at‑home therapy.

Diagnosis

Diagnosis is typically straightforward, but a clinician may use the following steps to confirm:

1. Physical examination: Visual inspection for the characteristic black dots and the wart’s location.
2. Dermatoscopy: A handheld magnifying device that highlights vascular patterns unique to warts.
3. Acetate or “tape” test: Applying a clear adhesive strip to the lesion and examining the removed material under a microscope for HPV particles.
4. Biopsy (rare): If the lesion looks atypical or melanoma cannot be excluded, a small piece of tissue may be sent for pathology.
5. HPV typing (research settings): Laboratory testing to identify specific HPV strains, mainly for refractory cases.

Treatment Options

Management ranges from watchful waiting to procedural removal. The best approach depends on wart size, pain level, patient age, and immune status.

1. Over‑the‑counter (OTC) treatments

• Salicylic acid preparations (40%–80%): Applied daily after soaking the foot for 5–10 minutes. Works by slowly dissolving the thickened skin.
• Duct tape occlusion: Cover the wart with an airtight tape for 6‑7 days, remove, soak, and gently debride. Re‑apply until the wart disappears (often 2–3 weeks).

2. Prescription topical medications

• Stronger salicylic acid or urea formulations.
• Imiquimod 5% cream: An immune‑modifier that stimulates the body’s antiviral response; applied several times per week for up to 16 weeks.

3. Cryotherapy (freezing)

Liquid nitrogen is applied in quick bursts to freeze the wart. Most clinicians perform 2–4 sessions spaced 2–3 weeks apart. Cryotherapy is effective for many patients but may cause blistering or temporary pain.

4. Electrosurgery & curettage

Under local anesthesia, the wart is scraped away (curette) and the base coagulated with an electric current. This method offers immediate removal but carries a small risk of scarring.

5. Laser therapy

Carbon dioxide (CO₂) or pulsed‑dye lasers target the wart’s blood vessels, causing it to shrink. Usually reserved for resistant or large warts.

6. Immunotherapy

• Intradermal Candida antigen: An injection that triggers a localized immune response, useful for multiple or stubborn warts.
• Squaric acid dibutylester (SADBE): Contact sensitizer applied in a controlled manner to promote immune clearance.

7. Surgical excision (rare)

Complete removal of the wart in a single procedure. Preferred when the lesion is large, atypical, or when histologic examination is required.

Home care while undergoing treatment

• Soak the foot in warm water for 10 minutes before any topical therapy.
• Gently file the surface with a pumice stone (after soaking) to improve medication penetration.
• Keep the area clean and dry; change socks frequently.
• Avoid walking barefoot in public areas.

Prevention Tips

Because plantar warts spread via direct skin contact, simple hygiene habits can dramatically reduce risk:

• Wear shower sandals or flip‑flops in public pools, gyms, and locker rooms.
• Do not share towels, socks, or shoes with others.
• Keep feet clean and dry; use antifungal powder if you tend to sweat.
• Inspect feet regularly, especially after sports or outdoor activities.
• Promptly treat any cuts, blisters, or calluses to maintain an intact skin barrier.
• Consider a daily foot soak with mild antiseptic (e.g., diluted povidone‑iodine) if you’re prone to warts.
• If a wart appears, avoid picking or scratching—it can spread the virus to adjacent skin.
• Maintain a balanced diet and adequate sleep to support immune health.

Emergency Warning Signs

Plantar warts are rarely life‑threatening, but certain signs warrant immediate medical attention:

• Sudden, intense pain that does not subside with rest or over‑the‑counter pain relievers.
• Rapid swelling, redness, or warmth spreading beyond the wart (possible cellulitis).
• Pus, foul odor, or drainage suggesting a secondary bacterial infection.
• Fever, chills, or feeling generally unwell alongside foot changes.
• Any lesion that changes color, bleeds excessively, or has an irregular border—could mimic skin cancer.

If you experience any of these symptoms, seek care promptly at an urgent care center or emergency department.

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Sources: Mayo Clinic, Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH) – MedlinePlus, American Academy of Dermatology (AAD), Cleveland Clinic, WHO Skin Health Guidelines.

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