You get foot fungus by coming into contact with dermatophytes, a group of fungi that feed on a protein called keratin found in your skin, hair, and nails. These organisms thrive in warm, moist environments and can reach your feet through contaminated surfaces, shared items, or simply from the conditions inside your own shoes. The infection, commonly called athlete’s foot, is one of the most widespread skin infections in the world.
What Actually Causes the Infection
Three species of fungi are responsible for most cases of athlete’s foot. They belong to a family called dermatophytes, the same type of fungus behind ringworm and jock itch. These organisms have evolved a specific trick: they produce enzymes that break down keratin, the tough structural protein that makes up the outer layer of your skin. First, one set of enzymes weakens the rigid bonds holding keratin together, making the protein flexible and vulnerable. Then a second set of enzymes cuts the weakened keratin into smaller pieces the fungus can absorb as food. This is why foot fungus targets the thick skin on your soles and between your toes rather than softer tissue elsewhere on your body.
Because these fungi eat dead skin cells on the surface, your immune system doesn’t always detect the invasion right away. The infection can establish itself quietly before you notice any symptoms.
How the Fungus Reaches Your Feet
Dermatophytes spread in two main ways: direct contact with an infected person or indirect contact with contaminated surfaces. Pool decks, gym showers, locker room floors, and shared mats are classic sources. The fungi shed from infected skin in tiny flakes that can survive on damp surfaces for extended periods. Walking barefoot across a wet changing room floor is one of the most common routes of transmission.
Shared items also carry risk. Towels, socks, and shoes that have touched an infected foot can harbor fungal spores. Borrowing someone’s shoes or using a communal towel at a gym creates an opportunity for the fungus to transfer to your skin.
You can also reinfect yourself. If you have athlete’s foot and touch your feet, then touch another body part, the fungus can spread. This is why jock itch and athlete’s foot often show up together.
Why Your Shoes Make It Worse
Contact with the fungus alone isn’t always enough. Your feet need to provide the right conditions for the organism to grow, and enclosed footwear creates exactly that. Inside a closed shoe, your foot generates heat and moisture with every step. Dermatophytes thrive in these warm, damp conditions.
Sweating heavily makes the problem significantly worse. People who sweat a lot or wear the same pair of shoes day after day without letting them dry out are at higher risk. Socks made from synthetic materials like nylon trap moisture against the skin, while cotton or moisture-wicking fabrics pull sweat away and keep the surface drier. Rotating between different pairs of shoes gives each pair time to air out, which disrupts the moist environment fungi need to multiply.
This is also why athlete’s foot is more common in warmer months and in tropical climates. Heat plus humidity equals ideal fungal real estate.
Who Is Most at Risk
Anyone can get foot fungus, but certain factors raise your chances considerably. People who spend long hours in closed shoes, including athletes, military personnel, and workers who wear boots all day, deal with it more often. Men are affected more frequently than women, though the reasons aren’t entirely clear.
Your immune system plays a significant role. When your body’s defenses are weakened, fungal infections take hold more easily and are harder to shake. People with diabetes are especially vulnerable because the disease can reduce blood flow to the feet and impair immune responses in the skin. Cancer treatments like chemotherapy lower white blood cell counts, which the immune system relies on to fight infections. Organ transplant recipients take anti-rejection medications that deliberately suppress immune function, creating an opening for fungal growth. Long courses of antibiotics can also increase risk by disrupting the balance of microorganisms on the skin, giving fungi less competition.
Skin injuries matter too. A small cut, blister, or crack between the toes gives the fungus a point of entry past the skin’s outer barrier. People with very dry, cracked feet are more susceptible for this reason.
What Foot Fungus Looks and Feels Like
Athlete’s foot doesn’t always look the same. It shows up in several distinct patterns depending on which fungus is involved and where it takes hold.
The most common form appears between the toes, typically in the spaces between the third, fourth, and fifth toes. You’ll notice peeling, scaly skin that may be red or whitish and waterlogged. It often itches or burns, and the skin can crack painfully.
A second pattern affects the soles and sides of the feet in what’s sometimes called a “moccasin” distribution because it follows the shape of a shoe’s sole. The skin becomes thick, dry, and scaly across the bottom of the foot and up along the edges. This version tends to be chronic and is often mistaken for simple dry skin.
A less common form produces small fluid-filled blisters, usually on the soles. These blisters can merge into larger ones and become quite painful. In severe cases, the skin between the toes breaks down into open, weeping sores that are vulnerable to bacterial infection on top of the fungal one.
Practical Steps to Avoid Infection
Prevention comes down to keeping your feet dry and limiting contact with contaminated surfaces. Wear sandals or flip-flops in communal showers, locker rooms, and pool areas. Dry your feet thoroughly after bathing, paying special attention to the spaces between your toes where moisture lingers.
Footwear choices matter more than most people realize. Wear open-toed shoes or sandals when you can. When closed shoes are necessary, choose breathable materials and swap to a different pair the next day so yesterday’s shoes can dry completely. Cotton socks absorb moisture better than nylon or other synthetics. If you sweat heavily, changing your socks midway through the day can make a real difference.
There’s also evidence that sock materials can actively fight fungal growth. A clinical study of 56 patients found that socks with copper-oxide fibers woven into the sole improved or resolved symptoms like scaling, redness, cracking, and itching in nearly all participants within about nine days. Copper has natural antifungal properties that damage fungal cell membranes and proteins on contact. While copper-infused socks aren’t a substitute for treatment if you already have an infection, they may help prevent recurrence.
Don’t share towels, socks, or shoes with others. If someone in your household has athlete’s foot, avoid walking barefoot on bathroom floors and wash shared bath mats frequently in hot water. Applying antifungal powder inside your shoes can help keep fungal populations down in footwear you can’t easily wash.