Pitted keratolysis is a bacterial skin infection that creates small, crater-like pits on the soles of your feet. It’s not a fungal infection, despite how it looks, and it’s one of the most common causes of persistent, severe foot odor. The condition is harmless but stubborn, and it won’t resolve on its own without treatment or changes to your foot environment.
What Causes the Pits
The infection is caused by bacteria that thrive in warm, moist skin. The two main culprits are Kytococcus sedentarius and several Corynebacterium species. These bacteria produce enzymes that literally digest the outermost layer of skin on your soles, breaking down the thick, protective keratin that normally keeps that surface tough and smooth. As the bacteria eat through this layer, they leave behind clusters of tiny round depressions.
The signature smell comes from sulfur-containing compounds that the bacteria produce as byproducts, including thiols, sulfides, and thioesters. This is why the odor is distinctly worse than typical foot smell. It has a sharper, more pungent quality that doesn’t go away with regular washing alone.
What It Looks and Feels Like
The pits are small, round, shallow depressions ranging from 0.5 to 7 mm in diameter. They cluster mainly on weight-bearing areas of the soles: the balls of the feet, the heels, and the areas under the toes. When the skin is wet or sweaty, the pits become more visible and sometimes merge together into larger eroded patches. The affected skin often looks white or soggy, especially after being in shoes for a long time.
Some people feel nothing beyond embarrassment about the odor. Others notice a burning sensation or mild soreness when walking, particularly if the pits are concentrated on pressure points. The skin may also feel slimy or slippery to the touch when wet. Pain is uncommon but not unheard of, especially in more extensive cases.
Who Gets It
The condition is driven almost entirely by moisture. Excessive foot sweating (plantar hyperhidrosis) is the single biggest risk factor. Beyond that, anything that keeps your feet sealed in a warm, damp environment raises your chances significantly.
- Occlusive footwear: Rubber boots, vinyl shoes, and non-breathable work boots trap moisture against the skin for hours.
- Prolonged wear: People who spend 8 or more hours in closed shoes daily, such as military personnel, factory workers, and athletes, are particularly susceptible.
- Hot, humid climates: Tropical and subtropical environments accelerate bacterial growth on the feet.
- Shared wet environments: Communal showers, locker rooms, and pool decks create ideal conditions.
The condition affects all ages but is most commonly diagnosed in young adults, particularly men, likely because of occupational and athletic exposure patterns rather than any biological difference.
How It’s Diagnosed
Most of the time, a doctor can diagnose pitted keratolysis just by looking at the soles of your feet. The combination of clustered crateriform pits and the characteristic sulfur-like odor is distinctive enough that further testing is rarely needed. In one study of 41 patients, clinical diagnosis was straightforward in nearly all cases, with the unique malodor alone helping confirm the condition.
When the diagnosis is less clear, a Wood’s lamp (a type of ultraviolet light) can help. Under this light, the pits glow a coral red color, which distinguishes the infection from other conditions. Doctors may also perform a Gram stain of skin scrapings to look for the rod-shaped bacteria under a microscope.
The most important distinction is ruling out tinea pedis, the common fungal foot infection often called athlete’s foot. The two conditions can look similar, especially when the skin is macerated and white. Fungal testing and Wood’s lamp examination help separate them. Plantar warts are another condition that can mimic pitted keratolysis, though warts tend to be raised and painful when squeezed, while the pits of this condition are flat depressions.
Treatment Options
Pitted keratolysis responds well to treatment, and most people see significant improvement within two to four weeks. The approach combines killing the bacteria with reducing moisture on the feet.
Prescription topical antibiotics applied directly to the soles are the standard first-line treatment. Your doctor will typically prescribe a cream or gel that you apply once or twice daily to the affected areas. These work by eliminating the bacteria responsible for both the pits and the odor.
Over-the-counter benzoyl peroxide is an effective alternative that you can try before seeing a doctor. A randomized controlled trial found that both 2.5% and 5% benzoyl peroxide significantly reduced foot odor and improved the pitted lesions, with about 65 to 69% of participants showing visible improvement. Since both concentrations worked equally well and had similar side effects, the lower 2.5% concentration is the preferred starting point. You apply it to clean, dry soles once daily. It’s the same ingredient found in acne washes and creams, available at any pharmacy.
Preventing Recurrence
Treatment clears the infection, but the bacteria will come back if the conditions that caused it don’t change. Moisture control is the most important factor in long-term prevention.
Cotton socks are your best option because they allow airflow to the skin. Synthetic or blended materials tend to trap moisture against the feet. Change your socks during the day if they get damp, and never put on yesterday’s pair. If you sweat heavily, carrying a spare pair is worth the minor inconvenience.
Footwear matters just as much. Shoes with good ventilation reduce bacterial growth dramatically. Avoid rubber boots when possible, and if your job requires them, change into breathable shoes during breaks. Rotate between at least two pairs of shoes so each pair gets a full day to dry out completely. Putting on damp shoes from the previous day is one of the fastest ways to trigger a relapse.
Wash your feet with soap and water every time you remove your shoes and socks, not just during your evening shower. Dry them thoroughly, especially between the toes. If excessive sweating is a persistent problem, an aluminum chloride antiperspirant applied to dry soles at night can significantly reduce moisture. This is the same active ingredient in clinical-strength underarm antiperspirants, and it works by temporarily blocking sweat glands on the feet.