A small hole or pit on the sole of your foot is most commonly caused by pitted keratolysis, a bacterial skin infection that creates clusters of tiny, crater-like depressions in the outer layer of skin. It is not the only possibility, though. Plantar warts, diabetic ulcers, and a handful of inherited skin conditions can also produce holes or pit-like lesions on the foot, each with a different look, feel, and level of urgency. The cause matters because the treatment is completely different for each one.
Pitted Keratolysis Is the Most Likely Culprit
If you look at the sole of your foot and see small, shallow pits clustered together on the ball, heel, or toes, pitted keratolysis tops the list of explanations. The pits are usually a few millimeters across, round or oval, and sometimes merge into larger eroded patches. They tend to appear on the weight-bearing areas where your foot presses hardest into your shoe. The skin around them often looks white or soggy, especially after your foot has been damp for a while.
The hallmark companion symptom is smell. Pitted keratolysis is one of the most common infectious causes of foot odor, and the smell can be striking even after a shower.1PubMed Central. Pitted keratolysis: an infective cause of foot odour Some people also notice a slimy or sticky texture on the affected skin, and the area can itch or feel mildly sore when walking, though it is sometimes painless enough that you only discover it by looking.
What Causes the Pits to Form
Pitted keratolysis is not a fungal infection, despite how often it gets mistaken for one. It is caused by bacteria, primarily species of Corynebacterium, Kytococcus, and Dermatophilus, that thrive in warm, moist environments. When your feet stay wet and enclosed for long stretches, these bacteria multiply and produce enzymes called proteinases. Those enzymes literally digest the thick outer layer of dead skin on your sole, chewing small craters into it and releasing sulfur compounds that account for the distinctive odor.2PubMed Central. Plantar pitted keratolysis: a study from non-risk groups
Healthy foot skin hosts a diverse community of bacteria, including Corynebacteriaceae and several other families, and under normal circumstances they coexist without causing problems.3PubMed. The foot microbiome The trouble starts when conditions tip in the bacteria’s favor: prolonged occlusion (shoes that don’t breathe), excessive sweating, thickened skin on the soles, and a rise in skin-surface pH all create the perfect setup for the organisms to overgrow and start breaking down keratin.2PubMed Central. Plantar pitted keratolysis: a study from non-risk groups
Who Gets Pitted Keratolysis
You do not have to be an athlete or a soldier to develop pitted keratolysis, but certain circumstances raise the odds considerably. Occupations that keep feet constantly damp are classic risk factors: military personnel, farmers, miners, fishermen, industrial workers, and anyone who spends long shifts in rubber boots or vinyl footwear.4DermNet. Pitted keratolysis Hot, humid climates accelerate the process. So does hyperhidrosis, which is a tendency to sweat excessively even when you are not particularly active. Obesity, diabetes, immunodeficiency, and naturally thick sole skin (keratoderma) are also recognized contributors.4DermNet. Pitted keratolysis
That said, plenty of people develop it without any dramatic risk factor. Wearing the same pair of sneakers every day through a warm summer, exercising without changing out of sweaty socks, or simply being someone whose feet sweat more than average can be enough. The condition is far more common than most people realize, and it often goes misdiagnosed as athlete’s foot because both involve peeling, odor, and macerated-looking skin on the sole.
Treating Pitted Keratolysis
The encouraging news is that pitted keratolysis usually clears up without heroic measures. Because bacteria cause it, antibiotics aimed at the skin surface work well. A systematic review of published cases found that the treatments with the strongest evidence are topical erythromycin, topical clindamycin, and benzoyl peroxide.5Journal of Comprehensive Dermatology. Pitted keratolysis. A systematic review of published cases and a proposed therapeutic algorithm In one treatment series, applying erythromycin 3% gel twice daily resolved both the pits and the excessive sweating within about ten days.6PubMed. Pitted keratolysis, erythromycin, and hyperhidrosis
Other options include mupirocin, fusidic acid, and aluminum chloride solution to tackle the sweating component directly.1PubMed Central. Pitted keratolysis: an infective cause of foot odour Benzoyl peroxide, the same ingredient sold over the counter for acne, is sometimes the easiest first step because you can buy it without a prescription. A wash or cream in the 2.5–5% range applied to clean, dry feet once or twice a day is a reasonable starting point if you cannot get to a doctor right away. Still, the overall evidence base remains thin. That same systematic review noted a lack of high-quality studies to firmly establish the best protocol, so if your pits are not improving after a couple of weeks of self-treatment, seeing a dermatologist is worthwhile.5Journal of Comprehensive Dermatology. Pitted keratolysis. A systematic review of published cases and a proposed therapeutic algorithm
Preventing Recurrence
Pitted keratolysis has a frustrating tendency to come back if the conditions that fed it in the first place do not change. Prevention boils down to keeping the sole of your foot as dry as possible. Washing feet daily with an antibacterial soap and applying an antiperspirant (even a standard underarm product) to the soles can help prevent recurrence.1PubMed Central. Pitted keratolysis: an infective cause of foot odour Rotating between two or more pairs of shoes so each pair dries out between wears makes a real difference. Moisture-wicking socks (merino wool or synthetic blends designed for sport) outperform cotton, which absorbs sweat and holds it against the skin. Taking shoes off whenever you reasonably can during the day and avoiding wearing the same pair of damp shoes two days running are small habits that add up.
If you have hyperhidrosis that goes beyond normal foot sweat, aluminum chloride preparations (available over the counter or by prescription in higher concentrations) applied to the soles at night can significantly reduce moisture output. For severe cases, a doctor may discuss iontophoresis or botulinum toxin injections into the feet, though those are more involved and rarely needed just for pitted keratolysis.
Plantar Warts Can Look Like Holes Too
Plantar warts are another common reason people notice what appears to be a hole in the foot. Caused by the human papillomavirus (HPV), plantar warts grow inward under the pressure of your body weight rather than protruding outward like warts on a hand. The result is a flat, firm lesion on the sole that can look like a rough-surfaced pit, sometimes surrounded by a ring of thickened skin. On close inspection, tiny black dots are often visible at the surface, which are small clotted blood vessels, not “seeds” as folklore sometimes claims.7Oxford Academic (British Journal of Dermatology). Differential diagnosis of plantar wart from corn, callus and healed wart with the aid of dermoscopy
The feel is different from pitted keratolysis. A plantar wart tends to be painful when you squeeze it from the sides, while pitted keratolysis pits are more tender with direct downward pressure (or not painful at all). Warts also usually appear as a single lesion or a small cluster, rather than dozens of tiny pits spread over a broad area. Trimming the surface skin with a blade (something best done by a clinician) makes the small blood vessels more visible and helps distinguish a wart from a callus or corn.8Oxford Academic (British Journal of Dermatology). Differential diagnosis of plantar wart from corn, callus and heeled wart with the aid of dermoscopy
Treatment options for plantar warts include over-the-counter salicylic acid preparations and cryotherapy (freezing) performed by a doctor. A large randomized trial comparing the two found that both approaches have modest success rates and that neither is dramatically superior to the other for sole-of-the-foot warts.9PubMed Central. Cryotherapy versus salicylic acid for the treatment of plantar warts (verrucae): a randomised controlled trial Patience matters: plantar warts can take weeks or months of treatment to resolve, and many eventually clear on their own as the immune system mounts a response to the virus.
Diabetic Foot Ulcers
For someone living with diabetes, a small hole in the foot carries a very different significance. Diabetic foot ulcers typically develop within a callus at a pressure point on the sole and often have a circular, punched-out appearance that can look startlingly like someone took a hole punch to the skin.10DermNet. Diabetic foot ulcer Crucially, these ulcers are often painless because diabetes damages the nerves that carry pain signals from the feet. That numbness means a wound can deepen and become infected before you even realize it is there, which is why delayed detection is one of the biggest dangers.10DermNet. Diabetic foot ulcer
If you have diabetes and notice any break in the skin on your foot, even a tiny one, treating it as urgent is not an overreaction. Diabetic foot ulcers can progress rapidly to deep tissue infection, bone involvement, and in worst-case scenarios, amputation. Daily foot inspection is standard medical advice for people with diabetes precisely because early detection makes the difference between a minor wound and a crisis. A hole in the foot that is surrounded by red, warm, or swollen skin, or that produces any discharge, warrants same-day medical attention.
Rarer Causes Worth Knowing About
A few less common conditions can also produce small holes or pit-like depressions on the foot. Knowing they exist can save you from months of misguided self-treatment.
Punctate palmoplantar keratoderma is an inherited condition in which hard, keratotic bumps appear on the palms and soles. These bumps can be picked or rubbed out relatively easily, leaving small pits behind.11Indian Journal of Dermatology, Venereology, and Leprology. Punctate palmoplantar keratoderma The key difference from pitted keratolysis is timing and family history: these bumps usually show up in adolescence or early adulthood, run in families, and do not come with the same soggy, foul-smelling skin. They also tend to affect the palms as well as the soles, which bacterial pitting almost never does.
Punctate porokeratosis is another rare variant, characterized by multiple tiny keratotic papules concentrated on the palms and soles. These lesions resemble small plugs or spiny bumps rather than soft pits, and can be mistaken for corns or other thickenings of the skin.12PubMed Central. A rare case of punctate porokeratosis treated with topical lovastatin/cholesterol Porokeratosis is a disorder of skin-cell maturation rather than an infection, so antibiotics and antifungals will not help. A dermatologist can confirm the diagnosis with a biopsy and discuss targeted options.
Foreign-body wounds are the least exotic but often overlooked possibility. Stepping on a thorn, a sliver of glass, or even a hair (yes, embedded hairs can cause small puncture wounds in foot skin) leaves a hole that may close over at the surface while the foreign material stays trapped below. If you notice a small hole with localized redness, swelling, or a sensation of something being “in there,” a minor foreign body is worth considering before you start Googling skin diseases.
How to Tell Which One You Are Dealing With
A few quick observations can help you narrow things down before you see a professional:
- Number of pits: Dozens of tiny, shallow craters clustered over the ball or heel points strongly toward pitted keratolysis. A single deeper hole is more suggestive of a wart, an ulcer, or a puncture.
- Odor: Strong foot smell that persists even after thorough washing favors pitted keratolysis. Warts and keratodermas do not typically produce odor.
- Black dots: Tiny dark specks visible in the lesion are characteristic of plantar warts, where small blood vessels have clotted near the surface.
- Pain pattern: Pain with side-to-side squeezing suggests a wart. Pain with direct downward pressure (or no pain at all despite looking alarming) could be pitted keratolysis or a diabetic ulcer.
- Skin texture: Soggy, whitish, macerated skin around the pits is typical of pitted keratolysis. A firm, rough-surfaced lesion with well-defined borders is more typical of a wart.
- Diabetes status: If you have diabetes and you find any wound on your foot, treat it as a potential ulcer until proven otherwise.
None of these observations replaces a proper examination. If you are uncertain, a visit to a podiatrist or dermatologist usually resolves the question quickly, sometimes with nothing more than a magnifying lens or a dermoscope.
The Role of Pressure and Friction
Whatever the specific cause, it is no coincidence that these lesions concentrate on the sole of the foot. The sole endures a combination of downward pressure and shearing force with every step you take. Research measuring the forces across the plantar surface during walking found that peak pressure and peak shear occur at different spots on the heel and forefoot, and at different moments during each stride. Under the forefoot, shear forces tend to spread tissue outward, while under the heel they create a dragging effect.13PubMed Central. Spatial relationships between shearing stresses and pressure on the plantar skin surface during gait
This mechanical environment has consequences. Repeated stress stimulates the skin to thicken into calluses, which provide protection but also create the dense keratin that pitted-keratolysis bacteria feed on. The same forces push warts inward instead of letting them grow outward. And in someone with diabetic neuropathy who cannot feel these stresses accumulating, they quietly produce tissue breakdown at the highest-pressure spots. Understanding the foot as a mechanically demanding environment explains why so many different conditions converge on this one small patch of skin.
When Self-Treatment Is Not Enough
Most cases of pitted keratolysis and many plantar warts respond to home measures or over-the-counter products within a few weeks. But there are situations where seeing a professional promptly matters:
- Worsening despite treatment: If you have been using an appropriate product for two to three weeks and the pits or lesion are not improving or are spreading, you may have the wrong diagnosis.
- Signs of deeper infection: Increasing redness, warmth, swelling, streaking up the foot, pus, or fever suggest the problem has moved beyond the skin surface.
- Diabetes or circulation problems: Any foot wound in someone with diabetes, peripheral artery disease, or immune suppression should be evaluated professionally, even if it looks trivial.
- Persistent pain: A small hole that causes significant pain with walking or standing may involve deeper structures and warrants examination.
- Uncertainty: If you cannot tell whether you are looking at pitted keratolysis, a wart, or something else, a dermatologist can sort it out in one visit and save you weeks of ineffective self-treatment.
Why Antifungal Creams Usually Do Not Help
One of the most common missteps people make when they notice pits on their feet is reaching for an over-the-counter antifungal cream. The assumption that any funky-looking foot problem must be athlete’s foot is understandable: athlete’s foot is common, the creams are everywhere, and the symptoms can overlap superficially. But pitted keratolysis is bacterial, not fungal, and antifungal ingredients like clotrimazole and terbinafine do nothing to the organisms responsible. People sometimes spend months applying antifungals while the condition persists or worsens, which delays appropriate treatment and lets the smell and skin damage continue.
The imbalance in the foot’s microbial community that leads to pitted keratolysis is fundamentally different from a fungal overgrowth.3PubMed. The foot microbiome The same bacterial dysbiosis can also create conditions that make the foot more hospitable to fungal or viral infections, so it is possible to have pitted keratolysis and athlete’s foot simultaneously. In that case, you might need both an antibiotic and an antifungal. But the antibiotic (or benzoyl peroxide) is the piece that addresses the pits. If you have been faithfully applying antifungal cream and the craters on your sole refuse to budge, switching to an antibacterial approach is the logical next step.