Keratolysis, most commonly referred to as pitted keratolysis, is a bacterial skin infection that affects the soles of the feet. It creates clusters of small, crater-like pits in the skin’s outer layer and is one of the most common causes of persistent, severe foot odor. Despite how alarming it can look, it’s a superficial infection that responds well to treatment and typically clears within a few weeks.
What Pitted Keratolysis Looks Like
The hallmark sign is multiple small, round depressions on the bottom of the foot, typically 0.5 to 7 millimeters in diameter. These pits cluster mainly on weight-bearing areas: the ball of the foot, the heel, and along the toes. The skin around and between the pits often looks whitish and soggy, especially after the feet have been wet. Soaking the feet in water actually makes the pitting more obvious, which can be a useful way to check.
The pits start as tiny defects along the natural creases of the sole and gradually widen into their characteristic crater shape. In some cases, individual pits merge together, forming larger, irregularly shaped erosions. The affected skin may feel slimy to the touch, a feature reported in roughly 70% of cases.
Symptoms Beyond the Pits
Excessive sweating is the single most common symptom. In a study of 53 patients, hyperhidrosis was the most frequently observed feature, and the condition rarely develops on feet that stay dry. Foot odor is the other defining complaint, present in nearly 90% of cases. The smell is notably stronger than typical foot odor because the bacteria responsible produce sulfur compounds, giving the feet a distinctly unpleasant, sometimes rotten-egg quality.
Some people also experience itching or a burning sensation while walking, though many cases are surprisingly painless. Because the infection only affects the outermost layer of skin (the stratum corneum), it doesn’t penetrate deep enough to cause serious pain or systemic illness. Still, the combination of visible pitting, sliminess, and strong odor can cause significant embarrassment and is often what drives people to seek help.
What Causes It
Pitted keratolysis is caused by several species of bacteria that thrive in warm, moist environments. The main culprits include Corynebacterium, Kytococcus sedentarius, Dermatophilus congolensis, Actinomyces, and Streptomyces. These bacteria are naturally present on skin but only cause problems when conditions allow them to overgrow.
Once they proliferate, these bacteria produce enzymes that break down keratin, the tough protein that makes up the skin’s outer layer. The enzymes essentially digest small tunnels and cavities into the surface of the sole, creating the visible pits. This process is entirely superficial. The bacteria don’t invade deeper tissue, which is why pitted keratolysis stays localized and doesn’t cause fever or spreading infection.
Who Gets It
Anyone whose feet spend long periods in warm, damp conditions is at risk. The classic high-risk groups are soldiers, sailors, athletes, industrial workers, and laborers who wear occlusive footwear for hours at a time. Tropical climates increase the risk further, and people who go barefoot in humid environments are also susceptible.
However, research suggests the condition is more common in the general population than previously thought. Studies focused on non-risk groups (people who aren’t soldiers, farmers, or manual laborers) have found that pitted keratolysis occurs at higher rates than expected. If you sweat heavily through your feet, wear the same shoes daily, or regularly exercise in closed-toe sneakers, you’re a candidate regardless of your occupation.
How It Differs From Athlete’s Foot
Pitted keratolysis is frequently mistaken for a fungal infection like athlete’s foot, and the two can even occur together. But there are practical differences. Athlete’s foot typically causes peeling, scaling, and cracking, often between the toes, and tends to itch intensely. Pitted keratolysis produces discrete, punched-out pits on the sole itself, with a slimy texture and much stronger odor. If you’ve been treating what you assumed was athlete’s foot with antifungal creams and nothing has improved, pitted keratolysis is a likely explanation. Antifungals don’t work here because the cause is bacterial, not fungal.
A healthcare provider can usually diagnose pitted keratolysis on sight. The pattern of pitting on weight-bearing areas, combined with the characteristic odor, is distinctive enough that lab tests or skin scrapings are rarely necessary.
Treatment and Recovery
Pitted keratolysis responds well to topical antibacterial treatments. Most people see significant improvement within two to four weeks of consistent treatment. The pits gradually fill in as the outer skin layer regenerates, and the odor typically resolves before the skin fully heals.
Equally important is addressing the moisture that allowed the infection to develop. Practical steps that make a real difference include rotating between at least two pairs of shoes so each pair dries fully between wears, choosing moisture-wicking socks made from synthetic or merino wool blends rather than cotton, and applying an antiperspirant to the soles of the feet. Over-the-counter antiperspirants containing aluminum chloride, the same active ingredient in clinical-strength underarm products, can significantly reduce plantar sweating.
Washing feet thoroughly with antibacterial soap each day, drying them completely before putting on socks, and going barefoot at home when possible all help keep the skin surface hostile to bacterial overgrowth. For people with severe hyperhidrosis that doesn’t respond to topical antiperspirants, prescription options exist to reduce sweating more aggressively.
Preventing Recurrence
Pitted keratolysis has a tendency to come back if the underlying moisture problem isn’t managed long term. The bacteria responsible are part of the normal skin flora, so you can’t eliminate them permanently. What you can control is whether conditions favor their overgrowth. Keeping feet dry is the single most effective prevention strategy. If your job or sport requires prolonged time in closed shoes, changing socks midday and using foot powder or antiperspirant before activity can be enough to prevent a recurrence. People who’ve had pitted keratolysis once tend to recognize the early signs quickly: a return of the distinctive odor or the faint beginnings of pitting, both of which respond faster to treatment when caught early.