Reviewed by Evan Lewis, PhD. Last updated 11 August 2026.
Athlete's foot is caused by dermatophytes, a group of fungi that feed on keratin in the outer layer of skin. One species, Trichophyton rubrum, accounts for about 70% of cases. The fungus is already common on gym floors and shower rooms, and it needs warmth and damp to take hold.
That second half is the part most people skip. Picking up the fungus is easy and almost universal. Whether it turns into an itchy, peeling toe web depends on what your feet are like when it lands.
Which fungus causes athlete's foot?
Three organisms account for nearly all of it. The StatPearls chapter on tinea pedis puts T rubrum at roughly 70% of cases, with T interdigitale and Epidermophyton floccosum responsible for the remainder. Trichosporum violaceum shows up occasionally.
Which one you have changes what it looks like, which is why two people can both have athlete's foot and describe completely different feet.
| Organism | Share of cases | What it tends to look like |
|---|---|---|
| Trichophyton rubrum | About 70% | Scale over the sole and sides of the foot, the pattern DermNet calls the moccasin type |
| T. interdigitale | Most of the rest | Itchy erosions and scale between the toes, and more likely than T. rubrum to produce pustules |
| Epidermophyton floccosum | The remainder | Interdigital scaling, often alongside groin involvement |
| T. indotineae | Rare in North America so far | StatPearls flags it as resistant to traditional antifungal treatments |
That last row matters if a cream that should have worked did nothing. It is not the usual explanation, but it is a real one, and it is a reason to get a scraping rather than to buy a third cream.
What does the fungus actually feed on?
Keratin. Dermatophytes live in keratinised tissue, meaning hair, nails and the outer layer of skin. StatPearls describes the mechanism plainly: once the dermatophyte gets into the skin it sticks using adhesins in its cell wall, then releases proteases such as serine subtilisin and fungalysin that digest keratin.
The immune response is what you actually feel. Your keratinocytes produce cytokines to fight the fungus, and the itch, redness and peeling are that fight, not the fungus itself. The fungus also fights back. Molecules in its cell wall called mannans suppress the immune response, which is part of why it settles in and stays.
Where do you pick it up?
Floors you share barefoot, and skin you touch. NHS lists two routes: walking barefoot where someone with athlete's foot has walked, especially changing rooms and showers, and touching the affected skin of someone who has it.
DermNet adds shared towels to the list. And the household angle is bigger than most people expect. A 2022 scoping review of transmission between household members found onychomycosis and dermatophytosis passing between people living together in 44% to 47% of the households it looked at.
So the barefoot walk across a wet changing room is the famous route, but the shared bath mat at home is the one that keeps a family reinfecting each other. How long fungus survives on surfaces covers what that means for floors, socks and shoes.
Why do some people get it and others do not?
Because exposure is not the whole story. StatPearls lists four things that let dermatophytes grow: a hot and humid environment, prolonged use of tightly fitting footwear, excessive sweating, and prolonged exposure to water.
DermNet adds a second set of risk factors on the person rather than the shoe. Occlusive footwear such as heavy industrial boots, hyperhidrosis, underlying immunodeficiency or diabetes mellitus, systemic corticosteroids or immune suppressive medications, and poor peripheral circulation or lymphoedema.
Read those two lists together and the shape is obvious. Almost every item is about how long your foot stays warm and wet. Sweat is doing more of the work than the changing room floor. If your feet are damp most of the day, why feet sweat and what changes it is the more useful thing to fix first.
Can eczema cause athlete's foot?
No, but the two are easy to mix up and they can make each other worse. Eczema does not produce the fungus. What it does is break the skin barrier, and NHS notes you are more likely to get athlete's foot if the skin on your feet is damaged.
Going the other way, DermNet lists foot eczema, especially pompholyx and irritant contact dermatitis from persistent moisture between closely adherent toes, as one of the main things athlete's foot gets confused with. Contact allergy to something in the shoe, such as a rubber accelerant, shoe adhesive or leather tanning agent, is on that same list.
The practical version: if an antifungal cream has done nothing after a few weeks, the diagnosis is the thing to question, not the cream.
Does athlete's foot spread to your hands?
It can. NHS specifically lists the infection spreading to other parts of the body such as the hands as a reason to see a GP, and tells you not to scratch the affected skin because that is how it travels.
DermNet also advises checking the other typical sites when tinea pedis is suspected, meaning toenails, groin and the palms of the hands. The nail is the one that catches people out, because a nail that has picked it up becomes a reservoir that keeps reseeding the skin long after the skin looks fine.
What the causes point to for a daily routine
Every cause on those lists is about moisture, contact or a broken barrier, so the routine that follows is short.
- Dry between the toes properly. NHS says dab rather than rub, and use a separate towel for your feet.
- Do not wear the same shoes two or three days running. That is NHS advice, not ours, and it exists so the inside of the shoe can dry out.
- Flip flops in shared showers and changing rooms.
- Clean socks daily, and do not share towels, socks or shoes.
- Deal with the sweat, because excessive sweating sits on both risk lists.
Sole Shield is the two-ingredient iodine and water spray we make for the skin of the foot and the inside of shoes, and it is built to sit inside that routine rather than replace any of it.
Common questions
What type of infection is athlete's foot?
A superficial fungal infection of the skin, known medically as tinea pedis. It sits in the outer keratin layer rather than in deeper tissue, which is why it is treated on the surface rather than with something systemic in most cases.
What is the pathogen that causes athlete's foot?
A dermatophyte fungus. StatPearls names Trichophyton rubrum as the cause of around 70% of tinea pedis, with T. interdigitale and Epidermophyton floccosum accounting for most of the remainder.
Is athlete's foot caused by poor hygiene?
No. It is caused by contact with a dermatophyte plus conditions that let it grow, and the risk factors StatPearls lists are heat, humidity, tight footwear, sweating and prolonged water exposure. Clean feet in wet boots all day are at more risk than dusty feet in sandals.
Can eczema cause athlete's foot?
Eczema does not cause the fungus, but damaged skin makes infection more likely, and NHS lists damaged skin as a risk factor. Foot eczema is also one of the conditions DermNet says tinea pedis is most often confused with.
Can athlete's foot spread to your hands?
Yes. NHS lists spread to other parts of the body such as the hands as a reason to see a GP, and says not to scratch the affected skin because scratching moves it. DermNet advises checking the palms, groin and toenails when tinea pedis is found.
Does sweating cause athlete's foot?
Sweating does not create the fungus, but it is one of the four growth conditions StatPearls names, alongside heat, tight footwear and prolonged water exposure. DermNet lists hyperhidrosis as a risk factor in its own right.
Can you get athlete's foot without going to a gym?
Easily. The 2022 scoping review found dermatophyte transmission between household members in 44% to 47% of households studied, so a shared bath mat, a shared towel or a family member's untreated nail is enough.
Is athlete's foot a disease?
It is an infection, and it is contagious. It is not a disease in the sense of something your body developed on its own, which is why the fix involves the environment around the foot as much as the foot.
Why does athlete's foot keep coming back?
Usually because the reservoir was never dealt with. Shoes, socks, floors and the toenails all hold dermatophytes, and the conditions that let it grow the first time are usually still there.
The bottom line
Athlete's foot is a dermatophyte infection, most often T. rubrum, that digests keratin in the outer layer of skin. You catch it barefoot on shared floors or from someone else's skin, towel or nails. Whether it takes hold comes down to heat, sweat, occlusive shoes and broken skin. Fixing the moisture matters as much as anything you put on it, and if a cream has done nothing after a few weeks, get the diagnosis checked rather than buying another one.
