How to Get Rid of Plantar Warts: Why They're So Stubborn and What Works
What Are Plantar Warts and What Causes Them?
Plantar warts are flat topped raised bumps that appear on the bottom of the feet (and sometimes hands), caused by an infection with the human papillomavirus (HPV) — usually strains 1, 2, or 4. We believe this occurs after the virus enters through tiny breaks in the skin, often in pressure areas like the heel or ball of the foot. This type of wart is extremely common and if not treated in a timely manner, can spread to other areas on the skin or to other people around you.
Unlike regular warts, plantar warts grow inward within the skin, not outward. Part of this is likely because of constant pressure from walking. They often look like rough, grainy patches with tiny black dots (we call these thrombosed capillaries) and can feel like walking on a corn kernel. The thrombosed capillaries are a tell-tale sign that they are likely still active, and is a clue to patients doing home treatments that their wart is still active.
Plantar warts are:
Caused by direct or indirect contact with HPV
Common in children, teens, and athletes. They are more resistant in adults
Contagious, especially in moist environments like locker rooms or pool deck
What About the Mechanism Makes Them So Hard to Treat?
Several biological and mechanical factors make plantar warts resistant to treatment:
Thick skin barrier: The soles of the feet have the thickest stratum corneum on the body, making it harder for topical treatments to penetrate to the infected tissue.
The stratum corneum on the soles of the feet is approximately 5–10 times thicker than on areas like the forearm or upper arm. For comparison of the epidermal thickness:
Soles of the feet: ~400–600 micrometers (μm)
Forearm/upper arm: ~50–100 μm
HPV hides from the immune system: The virus doesn’t elicit a strong immune response. It lives quietly in the upper layers of skin, where it can avoid detection because it is far from the local immune surveillance. Strangely, langerhan cells which are powerful immune cells do exist in the epidermis even on the feet, so it's unclear why warts seemingly evade the immune system.
Callus formation: Pressure from walking causes thickened skin or what dermatologists refer to as hyperkeratosis, which builds up over the wart and makes it harder to reach. It's almost like a shield that covers the wart. If this is not removed before applying treatment, it essentially blocks the treatment from reaching the wart.
Low blood flow: The feet naturally have reduced blood circulation compared to other body parts, which may slow the immune response. This is a hypothesis and may not necessarily be the primary mechanism underlying their resistance.
Gravity: The pressure of standing and walking causes the wart to embed deeply and can make treatments less effective.
What Is the Most Successful Office Treatment?
According to multiple clinical studies and dermatology guidelines, cryotherapy with liquid nitrogen is the most widely used and moderately effective office-based treatment. It's done every 3-4 weeks and works by freezing the wart tissue, causing blistering and destruction of HPV-infected cells as the frozen tissue thaws.
However:
Success rates vary widely and is very operator dependent [~50–70%]
It’s painful and may require multiple visits
Paring (debriding) the wart beforehand from a rational standpoint improve cure rates - and this is often not performed by the operator!!! Has evidence rating of B according to the AAFP.
Recurrence is still possible if HPV remains in surrounding tissue
Other in-office treatments:
Cantharidin (a blistering agent, often used in children). Often used as a compounded combination treatment with salicylic acid and podophyllin [81-96%].
Immunotherapy (e.g., Candida antigen [66%] injections or cidofovir injections commonly, 5FU [59%] or bleomycin less commonly)
Electrofulguration, a form of electrosurgery that uses high-frequency electric current to destroy superficial tissue but is very operator dependent, can lead to scarring / pain, and can create smoke plumes which contain HPV DNA.
Laser therapy with pulsed dye laser (more aggressive, not easily accessible and often not covered by insurance) [69%].
Microwave treatment devices (emerging treatment option with low adoption) [75-83%]
What Is the Best Over-the-Counter Treatment?
The gold standard OTC treatment is salicylic acid [30-60% cure rate], a keratolytic that peels away the outer layers of skin. It's widely available in liquid form, gels, and medicated pads. Their concentrations vary between 20-40%, depending on solution form or gel form.
Pros:
Generally painless and easily accessible
Safe for long-term use
Can be effective over time (especially when used with paring and occlusion)
Cons:
Requires daily use for weeks or months, so a major time commitment
Penetration can be poor in thick plantar warts
Less effective if not paired with pre-soaking and dead skin removal
Other OTC options:
Cryotherapy kits: Use dimethyl ether most commonly; less powerful than in-office freezing with varying success rates in the literature
Duct tape occlusion: Low evidence, but some anecdotal benefit
Home remedies like garlic extract and bee venom have also been tried with cure rates lower than office treatment
Why They Resist Treatment and Recur
Even when a plantar wart appears to “go away,” recurrence is common. Here's why:
HPV can persist in nearby skin, even when the wart is no longer visible. After each visit with a patient, the wart may appear to go away, only to return at the next visit.
The immune system may not recognize the wart as a foreign material. The longer it's been with you, the more likely the immune system has begun to think that it's simply a part of you (theory).
Incomplete treatment (not reaching deep wart tissue or surrounding wart tissue) allows it to grow back.
Pressure and friction from walking can re-irritate the site, leading to reactivation and reinfection.
Some plantar warts also evolve into mosaic warts — clusters of smaller warts that are particularly stubborn and would most definitely require in office treatment.
Gaps in the Science
Despite being common, plantar wart treatment is an area with few definitive answers. Even now, we are not entirely sure why they are resistant to treatment. Many of the above explanations are scientific theories. For instance, is it really the case that immune recognition would cause them to go away?
Even now, there are no FDA approved prescription drugs or devices for plantar warts.
Many treatments rely on stimulating the immune system, but the mechanisms are not well understood
There’s no consensus on the best treatment plan for recalcitrant (treatment-resistant) warts
A better understanding of HPV’s evasion tactics, skin barrier penetration, and host immune responses could lead to more effective therapies. In the next part of this series, we will perform a literature review to better understand the pathophysiology of plantar warts which might shed some light on possible ways to approach drug development.
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Q: Are plantar warts contagious?
Yes — HPV spreads via direct or indirect contact, especially in moist, communal environments.Q: Can you prevent plantar warts?
You can reduce risk by wearing sandals in public showers, avoiding barefoot walking in gyms, and not picking at existing warts.Q: What if nothing works?
See a dermatologist. Recalcitrant warts may require injections, laser ablation, or immunotherapy.Q: Should I pare or file down the wart?
Yes. Most treatments work better if you remove dead skin before applying medication. Historically derms have recommended using a pumice stone, but recently they are believed to increase the spread of warts by causing microabrasions in the skin. On the other hand, a blade might be considered unsafe. -
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