Warts on the feet: treatment and prevention of recurrence

Plantar warts, or warts on the feet, are benign skin growths caused by human papillomavirus infection. They form on the weight-bearing areas of the foot and can cause significant discomfort when walking due to the pressure of body weight. They resemble calluses but contain thrombosed capillaries, often resulting in visible black spots on the surface. These are not simply cosmetic: pain, limited activity, and the risk of secondary infection make the problem clinically significant. [1]

There are over 200 types of human papillomavirus. Plantar warts are most commonly associated with types 1, 2, 4, and several other variants that prefer the skin of the soles. Infection occurs through direct contact with the skin or through moist surfaces where the virus can persist, especially in public areas. Portals of entry are microcracks and maceration. [2]

Plantar warts are characterized by two clinical phenotypes. A deep, solitary wart called a "myrmecia" grows inward, is painful when pressed, and is more often associated with human papillomavirus type 1. "Mosaic" warts are superficial clusters of multiple lesions, are less often painful, and are often associated with human papillomavirus type 2. Distinguishing between the phenotypes helps explain to the patient the potential persistence of symptoms and the choice of treatment. [3]

Although some warts may disappear spontaneously, plantar warts are particularly prone to persistent growth due to constant mechanical stress. Therefore, if pain, increased size, or ineffective treatment are present, active treatment under medical supervision is warranted. [4]

ICD-10 and ICD-11 codes

The International Classification of Diseases, Tenth Revision, provides a separate code for plantar warts. This is a convenient tool for standardizing diagnosis, patient referral, and maintaining statistics on viral skin lesions. The use of a specific code reflects the anatomical location and allows for differentiation of plantar warts from other variants. [5]

The eleventh revision of the International Classification of Diseases (ICD) structured viral warts in more detail, including a separate entry for plantar warts. This helps to more accurately code cases, taking into account clinical differences and the complexity of treatment specifically on the supporting surface. [6]

In practice, the 10th revision code for plantar wart is often used in documentation, as it is familiar and supported by medical information systems. When transitioning to the 11th revision, it is recommended to specify the new category to improve data quality. [7]

Below is a summary table for quick code selection.

Table 1. Codes and formulations

Classifier	Code	Formulation
ICD-10	B07.0	Plantar wart
ICD-10	B07.8	Other viral warts
ICD-10	B07.9	Viral wart, unspecified
ICD-11	1E80.1	Plantar warts
ICD-11	1E80.0	Periungual and digital warts

[8]

Epidemiology and transmission factors

Plantar warts are common, especially among children, adolescents, and young adults who actively use swimming pools and participate in sports. Some lesions regress spontaneously, but the time frame is unpredictable and depends on the immune response and mechanical stress. Spontaneous resolution is less common on the soles of the feet than on the hands due to constant compression and friction. [9]

The virus is transmitted by direct skin-to-skin contact and through moist surfaces where it persists. The risk is higher in the presence of maceration, microcracks, hyperhidrosis, and in people who walk barefoot in showers and locker rooms. Shared razors, pumice stones, and towels can also transfer the virus between skin areas. [10]

Immune status influences the clinical picture. In immunocompromised states, warts tend to persist for a long time, tend to develop multiple lesions, and are less responsive to standard treatment methods. This explains the need for early escalation of therapy in such patients. [11]

Seasonality and climate influence lifestyle. In summer, contact with common surfaces and the intensity of sports increases, while in winter, maceration occurs due to tight footwear. Therefore, preventative recommendations always include skin care and proper footwear selection. [12]

Pathogenesis: Why the painful hyperkeratosis cap forms

Human papillomavirus infects basal keratinocytes through microdamage to the skin. When the wart is plantar, vertical growth is limited by pressure, causing the wart to grow inward, forming a dense hyperkeratotic cap. Dark spots are often visible within the capillaries—these are thrombosed capillaries that feed the wart. [13]

The skin's immune response may be insufficient to quickly eliminate the virus, especially with constant microtrauma. This explains the frequent pain with lateral compression and the increased resistance of plantar lesions to therapy compared to other locations. [14]

The "Myrmecia" phenotype is characterized by a deep invasive element, which, under the influence of support, is further pressed into the dermis, increasing pain and limiting running and walking. "Mosaic" warts form superficial fields of multiple lesions and are less painful, but are often annoying due to the size of the lesion. [15]

Histologically, the wart is a papillomatous hyperplasia of the epidermis with hyperkeratosis and parakeratosis, as well as dilated papillary vessels. These features explain the characteristic clinical picture and behavior during keratolytic therapy. [16]

Symptoms and types of plantar warts

Classic symptoms include pain when walking, a "pebble in the shoe" sensation, and increased pain with lateral pressure on the lesion. Black spots are visible on the surface, and the skin pattern is interrupted. A dense halo of hyperkeratosis, similar to a callus, often forms around the lesion. [17]

A distinction is made between a deep, solitary, myrmecia-like form and a mosaic variant, consisting of multiple superficial lesions. The former is often painful and more resistant to treatment, while the latter often covers a larger area and interferes with everyday footwear. Knowing the variant is important for choosing a treatment method and determining treatment time expectations. [18]

In adolescents and young adults, fresh lesions with a relatively short history are more common, while in adults, persistent, recurring warts are common, especially with occupational exposure to the feet. In people with immunodeficiency, multiple and large lesions are possible. [19]

Plantar warts are often associated with hyperhidrosis of the feet and maceration of the interdigital spaces, which increases the risk of secondary bacterial and fungal infection and makes treatment longer. [20]

When to see a doctor

You should see a doctor if the foot lesion hurts when walking, grows, bleeds, interferes with sports, or does not respond to self-treatment within several weeks. Early treatment reduces the duration of treatment and the risk of secondary infection. [21]

If you have any doubts about the diagnosis, consult a specialist, especially if the lesion is pigmented, rapidly changing, has jagged edges, or is ulcerated. In such situations, it is important to rule out other skin conditions, including neoplasms. [22]

Patients with immunodeficiency and diabetes are not recommended to self-medicate for long periods without medical supervision due to the increased risk of complications and atypical course of treatment. The choice of method and intensity of treatment requires individual assessment. [23]

If warts are multiple, spreading, affect the nail folds, or are present on the hands and other areas, the doctor will help choose a strategy, combining local, hardware, and immune methods. [24]

Diagnostics: from clinical examination to dermatoscopy

In most cases, the diagnosis is made clinically. The doctor looks for interruptions in the skin pattern, thrombosed capillaries, and characteristic tenderness when pressed. Preliminary gentle removal of the stratum corneum enhances the visualization of the signs. [25]

Dermoscopy improves diagnostic accuracy by allowing visualization of vascular points and the distribution of hyperkeratosis. This is particularly useful for distinguishing warts from calluses and other keratoses. Biopsy is rarely required and is performed in cases of atypical signs, suspicion of another disease, or treatment failure. [26]

Laboratory confirmation of the virus is not routine. HPV typing for plantar warts does not influence treatment decisions and is not routinely performed. Exceptions include research objectives and rare diagnostic challenges. [27]

In painful areas and in athletes, it is useful to assess concomitant hyperhidrosis and the condition of footwear. This allows for the simultaneous elimination of provoking factors, increasing treatment success. [28]

Differential diagnosis

The most common conditions with which plantar warts are confused are calluses and corns. Unlike warts, calluses retain their skin markings, and scraping does not produce pinpoint hemorrhages. Pain from calluses increases with vertical pressure from above, while pain from warts is more pronounced with lateral pressure. [29]

Rare but important "masks" include porokeratosis, punctate keratodermas, and epidermal cysts, which on the soles may be associated with human papillomavirus type 60. If the lesion has an atypical appearance and does not respond to standard treatment, consultation with a dermatologist is useful. [30]

Pigmented or ulcerated lesions require the exclusion of other dermatoses, including tumors. The decision to perform a biopsy is made by a physician based on the clinical presentation and dermatoscopy. [31]

Systemic mycoses and bacterial infections occur as complications, not as mimicry. Their timely detection is important for patient safety and comfort. [32]

Table 2. Differences between warts, calluses and some keratoses

Sign	Plantar wart	Corns and calluses
Skin pattern	Interrupted	Saved
Blackheads	Yes, thrombosed capillaries	No
Pain	More severe with lateral compression	Stronger with vertical pressure
Response to keratolytics	Yes, but a course is required	Often relief after unloading

[33]

Treatment: An evidence-based "ladder" from simple to complex

The first-line treatments for most patients are topical keratolytics based on salicylic acid and cryotherapy with liquid nitrogen. Both methods have moderate efficacy, acceptable safety, and are affordable. Combination with regular gentle exfoliation of the stratum corneum improves results. [34]

Salicylic acid is used daily for courses lasting several weeks or months. The advantages are its low cost and the ability to be used at home if the instructions are followed. The disadvantages are the lengthy period and the need for discipline. The effect is better on fresh and small lesions. [35]

Cryotherapy is performed in cycles at intervals of approximately two to three weeks. Aggressive protocols yield higher clearance rates but carry a greater risk of side effects, so the regimen is selected individually. Preliminary softening and trimming of hyperkeratosis improves access to the wart tissue. [36]

In cases of relapse and persistent lesions, escalation methods are considered: cantharidin mixtures under occlusion, trichloroacetic acid, laser techniques, and intralesional injections of antiviral or immune drugs. The choice depends on the location, pain threshold, the presence of multiple lesions, and the patient's preferences. [37]

Table 3. First line of therapy

Method	How it works	Pros	Cons
Salicylic acid	Keratolytic softening and gradual destruction of tissue	Availability, home mode	Course duration, discipline
Cryotherapy	Tissue destruction by cooling and immune stimulation	Quick business card format	Pain, blisters, risk of hypopigmentation
Combination with debridement	Removing hyperkeratosis increases access to the lesion	Enhance the effect	Requires technique and accuracy

[38]

Immunotherapy and injection methods for stubborn warts

Intralesional immunotherapy with Candida antigens, measles-mumps-rubella, and other immune stimuli has received strong evidence for resistant lesions. The advantage of this approach is that it can clear not only the treated lesion but also distant warts by stimulating a systemic immune response. [39]

Current studies demonstrate high complete response rates and favorable safety profiles with appropriate patient selection. The optimal dose and administration schedule are debated, but even in the early stages, the method's potential as a next step after keratolytics and cryotherapy is demonstrated. [40]

Alternative injectable agents include bleomycin and acyclovir. They may be effective in some patients, but require experience and caution due to the risk of necrosis, pain, and other adverse effects. The decision to use them is made on an individual basis. [41]

It's wise to combine immunotherapy with skin care, hyperhidrosis management, and foot relief. This comprehensive approach increases the chance of long-lasting relief and reduces discomfort when walking. [42]

Table 4. When to consider immunotherapy

Situation	Why this makes sense	What to expect
Resistant foci	Increases the likelihood of cleansing	A response is possible in the treated and remote foci
Multiple warts	Systemic immune effect	Reducing the number of outbreaks without treating each one
Relapses after cryotherapy and keratolytics	New mechanism of action	A course of injections according to the scheme is required

[43]

Other methods and their place

Cantharidin and its combination with keratolytics are used by dermatologists under occlusion, causing blistering and lesion rejection. This method is well tolerated with proper technique, but drug availability may vary. The choice depends on the clinic and patient preference. [44]

Laser techniques, including pulsed dye and carbon dioxide lasers, are used to destroy tissue and coagulate vessels. Evidence suggests efficacy in resistant cases, but cost and availability limit widespread use. The decision is made after a discussion of the risks and expected outcomes. [45]

Surgical excision and curettage are rarely performed when other methods have failed or rapid de-obstruction of the painful area is required. Disadvantages include the risk of scarring and possible pain in the supporting area. Therefore, these methods are considered a reserve. [46]

Many "home" methods, including the isolated use of adhesive tape, produce conflicting results. They can be used as an adjunct to care, but not as a standalone therapy for stubborn plantar lesions. [47]

Skin care and relapse prevention

Proper footwear regimen reduces macrotrauma and maceration. It is recommended to air out shoes, avoid wearing the same pair two days in a row, and use moisture-wicking socks and absorbent insoles. This reduces the risk of viral spread and increases the effectiveness of any therapy. [48]

Hygiene includes careful removal of the stratum corneum before applying keratolytics, using disposable instruments, or thoroughly disinfecting reusable ones. After visiting pools and showers, dry your feet thoroughly and use individual towels. [49]

Controlling hyperhidrosis reduces maceration and improves medication tolerance. For those prone to increased moisture, reconsidering sock materials, using drying powders, and, if necessary, specialized treatments are helpful. [50]

Avoiding trauma to warts and self-picking reduces the risk of autoinoculation and spread. If pain or bleeding occurs, temporarily reduce the load and consult a specialist. [51]

Table 5. Everyday steps to reduce the risk of relapse

Direction	Practical step	Why is this necessary?
Shoes	Alternate pairs, choose breathable materials	Reduction of maceration and pressure
Socks	Change throughout the day, choose moisture-wicking fabrics	Humidity and odor control
Hygiene	Use a separate pumice stone and towel to dry the spaces between your toes.	Less chance of spreading the virus
Sports and swimming pool	Flip-flops in showers, dry thoroughly	Less contact with contaminated surfaces

[52]

Prognosis and patient expectations

Some plantar warts resolve on their own, but the timeframe is unpredictable, and pain and limitations often necessitate more aggressive treatment. The first line of treatment yields moderate clearance rates, so it's important to discuss the duration of treatments and the need for repeat treatments in advance. Strict adherence to instructions and regular debridement of the hyperkeratosis improve success. [53]

In resistant lesions, switching to immunotherapy or combination protocols allows for clearance where basic methods have failed. This transition does not signify "failure," but rather reflects a modern, stepwise approach. [54]

Patients with immunodeficiency and severe pain require an individualized strategy with early use of injections and hardware-based methods. In such cases, a pragmatic balance between the speed of relief and the risk of side effects is crucial. [55]

Even after successful treatment, relapses are possible, especially if triggering factors persist. Therefore, skin care, proper footwear, and moisture management are part of a long-term plan, not a temporary measure. [56]

Frequently Asked Questions

Is it possible to simply "wait it out" until the wart goes away on its own?
Sometimes yes, but on the soles of the feet, it lingers and is accompanied by pain. If it interferes with walking or grows, it's reasonable to treat it. [57]

Which to choose first: a keratolytic or cryotherapy?
Both options are considered first-line. The choice depends on preference, pain threshold, and lifestyle. Combinations are often helpful. [58]

Why inject immunotherapy if you can simply “burn it off”?
Immunotherapy triggers an immune response against the virus and is capable of removing even distant lesions, which is important for multiple warts. [59]

Are foot treatments dangerous?
With proper technique, the risks are minimal. Pain, blisters, and pigment changes are possible after cryotherapy, so the regimen is selected individually. [60]

Additional tables

Table 6. Step-by-step plan of the first line

Week	Action	Control
1-2	Removal of hyperkeratosis, initiation of salicylic acid	Tolerability and neatness of application
3-4	Repeated debridement, assessment of the effect	The decision to add cryotherapy
5-8	Repeat cryo every two or three weeks if needed	Recording dynamics and side effects
After 8	In case of resistance - immunotherapy	Discussion of the scheme and risks

[61]

Table 7. Red flags and indications for biopsy

Signal	Why is it important?	Action
Rapid growth and ulceration	A rare mask of other diseases	Consult a dermatologist to consider a biopsy.
Pigmentation and uneven edges	The differential series is wider	Dermoscopy, if in doubt - biopsy
Unusual location and appearance	Another nature of the process is possible	Re-evaluation of diagnosis
Severe immune deficiency	Atypical course and risk of complications	Escalation of treatment, narrow control

[62]