Common Warts (Verruca Vulgaris)

Common warts (verruca vulgaris) are benign, hyperproliferative skin growths caused by cutaneous infection of keratinocytes with human papillomavirus (HPV) — most often HPV types 2 and 4, and less commonly types 1, 3, 27, 29, and 57.^[1] They present as firm, rough-surfaced, dome-shaped or papilliform papules or nodules found most often on the hands, fingers, periungual skin, knees, and elsewhere on the body surface — this chapter covers exactly that presentation, not the sole-of-the-foot (plantar) wart, which behaves differently enough under load-bearing pressure to be managed in its own separate chapter.

Warts are extremely common in school-age children, affecting up to one-third of schoolchildren at any given time, with transmission increasing when a family member or classmate has warts,^[2] and they spread by direct skin-to-skin contact and by autoinoculation — scratching or picking a wart can seed the virus into a fresh break in nearby skin or under a fingernail.^[1] The single most important expectation-setting fact for patients and parents is that most common warts are self-limited: roughly half resolve spontaneously within about a year, and about two-thirds resolve within 12-24 months even without treatment, with resolution more likely and generally faster in younger children.^[2][1] For patients who prefer active treatment over watching and waiting, topical salicylic acid and cryotherapy are the 2 first-line, evidence-based options, and the pharmacist's core value lies in confirming the diagnosis, teaching correct application technique, setting a realistic timeline (this is a weeks-to-months therapy, not a days-to-clear one), and recognizing the minority of patients — an atypical or changing lesion, extensive disease in an immunocompromised patient, or a periungual wart threatening the nail — who need to move beyond self-care.

Typical appearance

A common wart is a firm, well-circumscribed papule or nodule, typically 2 mm to 1 cm across (though lesions can coalesce into larger plaques), with a distinctive rough, papilliform ("cauliflower-like") hyperkeratotic surface. Colour ranges from skin-coloured to grey-brown. Two features reliably distinguish a wart from a corn, callus, or scar on examination: paring away the surface with an emery board or scalpel reveals multiple small red, brown, or black puncta — thrombosed, dilated dermal capillaries — and the wart interrupts and disrupts the normal fine skin (dermatoglyphic) lines running across the area, where a callus or corn simply thickens the skin without erasing those lines.^[1][3]

A common wart (verruca vulgaris) on the finger, showing the classic rough, papilliform surface with visible small dark puncta from thrombosed dermal capillaries. (Klaus D. Peter, Wiehl, Germany, CC BY 3.0 DE, Wikimedia Commons)

Where they occur, and the variant patterns

• Hands and fingers are the most common site, including periungual warts clustered around or under the nail fold — these are frequently linked to nail-biting or cuticle-picking, are notoriously more resistant to treatment, and can distort nail growth if longstanding.
• Knees and elbows are common in children, often related to repeated minor trauma at these sites.
• Filiform (digitate) warts are a thin, finger-like or frond-like variant, most often seen on the face, eyelids, and neck — the thin projections make these easier to treat but more visible cosmetically.
• Autoinoculation along a scratch can seed a line of new warts (a pseudo-Koebner pattern), and picking at the free edge of a nail can seed a new subungual wart underneath it.

(a) Clustered common warts on a fingertip. (b) A filiform (digitate) wart on the eyelid margin — the thin, projecting variant typical of facial and periocular skin. (OpenStax Microbiology, CC BY 4.0, Wikimedia Commons)

Warts can be single or multiple, and lesions at different stages of growth (some flat, some raised) are common, particularly in children and in anyone who has been autoinoculating from an established wart.

• School age — warts affect up to about one-third of schoolchildren at any given time, with transmission increasing when a family member or classmate has warts.^[2]
• Direct contact with an infected person, or indirect contact with a contaminated surface, particularly where the skin barrier is already broken.^[1]
• Nail-biting, cuticle-picking, and other habits that create small breaks in the periungual skin — a major driver of periungual wart formation and of resistance to treatment at that site.
• Frequent minor skin trauma, or occlusive/moist skin conditions such as frequent hand-in-water occupations or atopic dermatitis with a disrupted skin barrier.
• Occupational exposure to raw meat, poultry, or fish — associated with a distinct HPV type (HPV-7, so-called "butcher's warts").
• Immunosuppression — solid-organ transplant recipients, HIV infection, and other causes of cellular immunodeficiency are associated with more numerous, more extensive, and more treatment-refractory warts, with the burden rising as the duration of immunosuppression increases.
• A personal history of warts, or ongoing autoinoculation from an untreated existing wart.

History

• Onset, duration, and growth pattern of the lesion(s); ask specifically whether the appearance or size has changed recently.
• Number and location of lesions, and whether new lesions have appeared in a line or cluster near an original one (suggesting autoinoculation).
• Any prior treatment — which product, how it was applied (was the surface pared first?), and for how long — since an incomplete or technically incorrect trial is the most common reason a lesion looks like "treatment failure."
• Household or classroom contacts with similar lesions, nail-biting/picking habits, occupation (e.g., meat/fish handling), and any history of immunosuppression.

Examination

Confirm the typical features described in Recognize the Condition: a firm, papilliform, hyperkeratotic papule that, when gently pared, reveals small thrombosed capillary puncta and shows interrupted skin lines. Examine for periungual or subungual involvement, and note the total number and distribution of lesions. No laboratory testing or imaging is routinely needed — diagnosis is clinical.

Differential diagnosis

Most classic hand, finger, knee, or periungual warts can be diagnosed clinically without further testing. Reserve biopsy for atypical presentations, lesions that are rapidly changing or bleeding, new adult-onset lesions with no clear preceding history of warts, and lesions that fail to respond to an adequate treatment trial.

• Set a realistic, evidence-based expectation from the first visit: most common warts resolve on their own, typically within 1-2 years, and watchful waiting is a genuinely reasonable choice for many patients, especially young children.^[2][1]
• For patients who choose active treatment, achieve visible clinical clearance with a first-line, evidence-supported option matched to the patient's age, the lesion's location, and their tolerance for discomfort.
• Minimize pain, scarring, and downtime, particularly for children and for lesions on the face or periungual skin.
• Limit spread — to other body sites through autoinoculation, and to other people through direct or indirect contact.
• Recognize early when a lesion needs to move beyond self-care: diagnostic uncertainty, an atypical or changing lesion, or a patient whose immune status makes standard therapy less likely to work.

• Discuss watchful waiting explicitly as a valid option — most common warts clear on their own within 1-2 years, more reliably and often faster in younger children.^[2][1]
• Cover exposed warts with a bandage or clothing in shared or communal settings, and avoid direct skin contact with a wart on another person.
• Do not pick, bite, or scratch a wart, and do not share nail clippers, emery boards, razors, or towels — all of these spread the virus by autoinoculation or to other people.
• Keep the surrounding skin barrier intact: manage nail-biting and cuticle-picking habits directly, since periungual skin breaks are a major driver of both new and recurrent periungual warts.
• Duct tape occlusion is a low-risk, low-cost option some patients want to try at home — evidence for it is genuinely mixed (one trial favoured duct tape over cryotherapy, others found no benefit over placebo), but because it is safe and well tolerated, it is reasonable to offer as an adjunct or an alternative for a patient who wants to avoid acids or freezing, while being honest that the evidence does not clearly support it over salicylic acid or cryotherapy.^[2][3]
• Pare down thickened, hyperkeratotic wart surface regularly with an emery board or pumice stone (a different one than used on normal skin/nails), whether or not the patient is also using an active topical therapy — this alone improves comfort and helps any concurrent treatment penetrate.
• Set the treatment timeline explicitly at the first visit — weeks to a few months for either salicylic acid or cryotherapy — so the patient does not stop a genuinely working therapy prematurely.

Pediatrics

Children are the population in which common warts are most prevalent and most likely to resolve on their own, so watchful waiting deserves equal billing with active treatment at every pediatric visit.^[2] When active treatment is chosen, salicylic acid is generally preferred for young children because it can be applied painlessly at home by a caregiver, while cryotherapy is generally reserved for older children and adults given the pain of the freeze and the multiple visits typically needed.^[3] Cantharidin is a useful in-office option specifically because its application itself is painless (the blister forms afterward), making it easier for young children to tolerate than cryotherapy.

Pregnancy and breastfeeding

Immunocompromised patients

Transplant recipients, patients with HIV, and others with cellular immunodeficiency develop more numerous, more extensive, and more treatment-refractory warts than immunocompetent patients, and the disease burden rises with the duration of immunosuppression. Conventional first-line therapy (salicylic acid, cryotherapy) is less reliably effective in this group.^[1] Treat actively rather than defaulting to watchful waiting, and use a lower threshold to refer early for dermatology-directed combination therapy (for example, cantharidin combined with other agents, or contact immunotherapy) rather than working through a prolonged standard OTC trial first.

Older adults

A wart-like lesion appearing for the first time in an older adult, without a preceding history of warts, deserves a higher index of suspicion for a mimicking malignancy — squamous cell carcinoma, keratoacanthoma, or amelanotic melanoma (see Red Flags/Refer and Assessment/Diagnosis) — rather than being treated empirically as a straightforward wart.

Reassess a salicylic acid course at the end of a full, adherent 6-12 week trial rather than at the first sign of slow progress — this is a genuinely slow therapy, and premature discontinuation is the most common reason it appears to fail.^[3] At follow-up, confirm the patient has actually been soaking and paring the wart before each application (not simply applying the product over intact hyperkeratotic skin) and using an occlusive dressing, since technique gaps are more often the problem than the drug itself.

For a patient undergoing cryotherapy, review response and tolerability at each visit, typically every 1-3 weeks, and adjust the freeze-thaw intensity and interval based on both clearance and blistering.^[2] Watch for local adverse effects of any home keratolytic therapy — irritation, chemical burn to surrounding skin, or unexpected pain — and stop or de-escalate if these occur.

For patients choosing watchful waiting, no active monitoring visit is required, but confirm the patient knows to return if the lesion changes character, grows rapidly, bleeds, or simply has not resolved within about 2 years, which should prompt reassessment of the diagnosis rather than continued waiting.^[1]

1. Confirm the diagnosis is genuinely a common wart, not one of its mimics (see Assessment/Diagnosis) — a lesion that "fails" salicylic acid or cryotherapy is sometimes simply not a wart.
2. Confirm technique and adherence before concluding a therapy has failed: was the wart soaked and pared before each salicylic acid application, was the dressing occlusive, was the full 6-12 week course actually completed daily, and for cryotherapy, was the patient attending every scheduled treatment interval?
3. If salicylic acid alone has been used adherently without adequate response, add or switch to cryotherapy, or combine the 2 — combination therapy outperforms either alone in a slow responder.^[3]
4. If an adequate trial of salicylic acid and/or cryotherapy (generally several cycles over 2-3 months) has genuinely failed, refer for cantharidin, contact immunotherapy, or laser therapy rather than repeating the same OTC regimen indefinitely.^[1]
5. At any point where the lesion looks atypical, is changing, bleeding, or growing rapidly — particularly a new lesion in an adult — stop empiric wart treatment and pursue biopsy rather than escalating to a stronger destructive therapy.
6. In an immunocompromised patient with a refractory or extensive presentation, refer early to dermatology for combination therapy rather than extending a standard stepwise trial.

• Applying salicylic acid directly over intact, unpared hyperkeratotic skin — paring the surface first is what allows the acid to actually reach and treat the wart.
• Stopping salicylic acid after 1-2 weeks because "nothing is happening" — a genuine trial needs 6-12 weeks of daily use.^[3]
• Presenting watchful waiting as if it were a lesser or default option rather than a legitimate, evidence-based choice with a real cure rate over time.
• Reflexively reaching for topical fluorouracil, bleomycin, or interferon — none of these outperform salicylic acid or cryotherapy for nongenital warts, and current evidence specifically recommends against bleomycin and interferons here.^[3]
• Using aggressive home destructive treatment (strong acids, unsupervised freezing) on the face or periungual skin, where scarring risk is higher and professional treatment is safer.
• Missing an atypical, rapidly changing, or new adult-onset lesion by assuming it is simply a stubborn wart rather than considering biopsy.
• Under-referring an immunocompromised patient with extensive or refractory warts by working through a full standard stepwise trial before involving dermatology.
• Not counselling on autoinoculation and transmission (nail-biting, shared nail tools, covering the lesion) alongside whichever active treatment is chosen, leaving an ongoing source of new lesions unaddressed.

How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.

Keratolytics (Topical, Self-Applied)

First-line active treatment for most common warts. Requires soaking and paring the wart surface before each application for full effect.

Cryotherapy

An equally reasonable 1st-line alternative to salicylic acid; no more effective overall, but gives higher patient satisfaction at the cost of more pain and blistering.

Office-Administered / Specialist Refractory-Wart Therapies

Reserve for warts that have not responded to an adequate, adherent trial of salicylic acid and/or cryotherapy.

Agents Not Recommended for Nongenital Warts

Listed to state explicitly that these should not be first choices, not as routine options.