Viral warts (verruca) !
Common, harmless skin growths caused by human papillomavirus, usually on the hands and feet. Many go away by themselves, especially in children.
Updated 2026-11-01
Structures involved
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Why it happens
- Oncogenic viruses and H. pylori: the table to know
- Tumour suppressor genes: RB, TP53, APC, BRCA and the two-hit hypothesis
- Hyperplasia: physiologic and pathologic
- Skin: epidermis layers, dermis, hypodermis
What it is
Benign proliferations of the epidermis caused by infection of keratinocytes with human papillomavirus (HPV). This page covers cutaneous warts on the hands, feet and face; anogenital warts are covered in the HPV infection page.
Who gets it
Very common, especially in school-age children and teenagers, and in people who work with meat or fish. Plantar warts spread in communal showers and swimming pools. Widespread or persistent warts are more frequent in people with HIV or organ transplants.
Causes
- HPV types 1, 2, 4, 27 and 57 for common and plantar warts
- HPV types 3 and 10 for flat warts
- Spread by direct skin contact or contaminated surfaces, entering through small breaks in the skin
- Self-spread by scratching, nail biting or shaving
Risk factors
- Childhood and adolescence
- Walking barefoot in communal areas
- Nail biting and skin trauma
- Wet work and handling raw meat or fish
- Immunosuppression (HIV, transplant, medications)
- Atopic dermatitis
Pathophysiology
HPV infects basal keratinocytes through tiny abrasions. The viral E6 and E7 proteins drive keratinocyte proliferation, producing epidermal thickening (acanthosis), excess keratin (hyperkeratosis) and koilocytes. Dilated capillaries in the papillae thrombose, forming the black dots seen in warts. The virus stays in the epidermis and evades the immune system, so warts persist until cell-mediated immunity recognises them.
Classification
- Common warts (verruca vulgaris): rough papules, often on fingers and hands
- Plantar warts (verruca plantaris): on the sole, pushed inward by pressure; mosaic warts when clustered
- Flat warts (verruca plana): small, smooth papules on the face and back of the hands
- Filiform warts: thin projections on the face or around the mouth
- Periungual warts around the nails
Symptoms and signs
- Rough, skin-coloured, dome-shaped papules with a cauliflower surface
- Small black dots (thrombosed capillaries) when pared
- Interruption of fingerprint or footprint skin lines over the lesion
- Pain when walking or standing with plantar warts
- Flat warts often appear in lines along scratches (Koebner phenomenon)
Diagnosis
- Clinical
- Clinical, based on the typical appearance, loss of skin lines and black dots after paring; dermoscopy can help.
- Tests
- Biopsy only if the diagnosis is uncertain or malignancy is suspected; histology shows hyperkeratosis, papillomatosis and koilocytes.
- Imaging
- Not needed.
Differential diagnosis
- Corns and calluses (skin lines preserved, no black dots, painful on direct pressure)
- Molluscum contagiosum (umbilicated papules)
- Seborrhoeic keratosis
- Actinic keratosis or squamous cell carcinoma
- Acral melanoma (pigmented plantar lesion)
Goal of treatment
Remove symptomatic or bothersome warts with the least scarring; treatment is optional, as many warts clear on their own.
Treatment
- Conservative
- Watchful waiting is reasonable, especially in children: most warts resolve within about two years.
- Medical
- Topical salicylic acid after soaking and paring is the usual first-line treatment; other options include topical cantharidin, imiquimod or retinoids for flat warts.
- Procedure
- Cryotherapy with liquid nitrogen repeated every few weeks; electrosurgery, curettage, laser or intralesional treatments for resistant warts.
- Follow-up
- Re-evaluate lesions that do not respond, bleed or change, and assess immune status when warts are extensive.
Complications
- Spread to other sites or to other people
- Pain and difficulty walking with plantar warts
- Scarring, pigment change or pain after destructive treatment
- Recurrence
- Rare malignant change in immunosuppressed patients with certain HPV types
Prognosis
Benign. Many warts disappear spontaneously within months to a couple of years, more often in children. Recurrence after treatment is common.
Prevention
- Wearing sandals in communal showers and pools
- Not picking, biting or shaving over warts
- Keeping feet dry and not sharing towels or footwear
- HPV vaccination prevents anogenital warts and HPV cancers, but not most common skin warts
Test yourself
Think of the answer, then tap the question to see it.
What causes common and plantar warts?
Human papillomavirus, mainly types 1, 2 and 4.
How can a plantar wart be told apart from a callus?
A wart interrupts skin lines and shows black dots (thrombosed capillaries) after paring; a callus keeps the skin lines.
What is the typical first-line treatment for common warts?
Topical salicylic acid, with cryotherapy as a common alternative.
What finding should prompt evaluation for immunosuppression?
Very numerous, extensive or treatment-resistant warts.
Related conditions
- Human papillomavirus (HPV) infection
- Molluscum contagiosum
- Cutaneous squamous cell carcinoma
- HIV infection and AIDS
- Cervical cancer
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Warts (MedlinePlus, US National Library of Medicine, 2026); Warts (MedlinePlus, US National Library of Medicine, 2026).
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