It’s normal for feet to have some odor, but feet that smell sour, rotten, or cheesy may indicate a problem. Sour foot odor is often caused by bacterial overgrowth on the skin of the feet and shows that conditions are right for fungal infections to take hold. Understanding what’s behind sour-smelling feet can help you take steps to freshen your feet.
Causes of Sour Foot Odor
Bacteria naturally live on the skin and thrive in the warm, moist environment inside shoes. When too much bacteria grow, they produce pungent odors as they break down dead skin cells. The most common bacteria found on smelly feet are Micrococcus sedentarius and Staphylococcus epidermidis. These bacteria feed on dead skin cells and sweat, producing acidic waste products that make feet smell sour.
Fungal infections are another major cause of sour foot odor. Athlete’s foot, caused by the fungus Trichophyton, thrives in damp shoes and sweaty feet. The infection creates a soft, white layer on the skin that emits a sour, cheese-like smell. Another fungal infection called pitted keratolysis eats away at the skin, forming crater-like pits that fill with foul-smelling bacteria.
Other factors can make mild foot odor turn sour:
- Excessive sweating (hyperhidrosis) provides moisture that bacteria need to multiply. Sweat itself is odorless, but bacteria feed on amino acids in sweat to produce vinegar-like odors.
- Going barefoot can expose feet to different bacteria that contribute to odor. Damp public showers and pools contain varieties of bacteria that may colonize the skin.
- Shoes made of non-breathable materials trap heat and sweat, creating an environment for odor-causing bacteria to thrive.
- Poor hygiene allows dead skin cells and sweat to build up. Infrequent washing removes protective oils and allows bacteria deeper access to the skin.
- Skin conditions like eczema or psoriasis cause excess skin cell buildup and inflammation that bacteria can feed on.
- Hormonal changes during puberty, pregnancy, and menopause can increase sweating and change foot odor.
- Some diseases and disorders affect foot odor. Diabetes can alter skin chemistry and sweat composition, producing a sweet, fruity odor. Liver or kidney problems hamper the body’s ability to eliminate waste, causing a strong ammonia smell.
- Genetics play a role. Some people naturally have more sweat glands than others or secrete chemicals in sweat that bacteria find particularly appetizing.
Treating Sour Foot Odor
Keeping feet clean and dry is the first line of defense against sour odors. Wash feet daily with antibacterial soap, scrubbing between the toes. Dry feet thoroughly, especially between the toes where moisture easily gets trapped. Dusting feet with antibacterial or antifungal powder can help absorb sweat during the day.
Wear clean, breathable socks made of natural fibers like cotton. Change socks at least daily, or more often if your feet sweat a lot. Let shoes air out between wearings so bacteria and moisture don’t accumulate inside. Consider wearing open shoes like sandals when possible.
Soak feet in diluted vinegar to help kill bacteria – the acidic environment drives away the bacteria that make feet smell sour. Tea tree oil is a natural antibacterial and antifungal – add a few drops to foot soaks or use tea tree oil wipes on your feet.
See a dermatologist or podiatrist if foot hygiene tips don’t improve odor, since fungal infections and skin conditions may require prescription medications. Oral antibiotics or antibiotic foot soaks can treat bacterial overgrowth, while antifungal creams, pills or medicated nail polish can eliminate fungal infections.
Practice good foot hygiene, allow shoes to dry between wears and choose breathable footwear to keep your feet – and your shoes – smelling fresh. But if you notice a bothersome cheesy or sour odor, consult a doctor, as medicated treatment may be needed to get rid of unpleasant foot smells. With the right prevention and treatment, you can keep your feet happy and odor-free.