Athlete's Foot and Why Nails Get Reinfected
The skin is the reservoir, the shoes are the second one, and a twelve-month nail treatment cannot outrun either of them.
Part of the Complete Fungal Nail Infection Guide.
Key fact: The skin is the reservoir. Athlete's foot clears in one to two weeks with cream, while a nail takes nine to twelve months — so an untreated foot will reinfect a nail many times over during a single course of nail treatment.
Why the two travel together
Athlete's foot and fungal nail infection are usually the same organism in two places. Fungus living on the skin between the toes finds its way under the nail, and once established in the nail it seeds back onto the skin indefinitely.
The asymmetry in treatment times is what makes this decisive. Skin clears in a week or two. A toenail takes the better part of a year. Treating the nail while ignoring the skin means running a twelve-month course against a source that reinfects it continuously.
The practical rule: treat the skin and the nail together, and keep treating the skin after it looks better.
What athlete's foot looks like
- Between the toes, most often the outer two — white, soggy, peeling or cracked skin
- Itching or burning, though a surprising number of people have none
- Dry, scaly skin across the sole and up the sides, which is frequently mistaken for dry skin and moisturised for years
- Small blisters on the arch or sole in some cases
- Cracks and fissures, which can be painful and matter for the reason below
- Often one foot worse than the other
Treating the skin
Terbinafine 1% cream is the usual choice, and works faster than older antifungals.
- Apply to clean, thoroughly dried skin, covering the area and a margin of about 2cm beyond it
- Include between all the toes, not only the obviously affected gap
- Treat the whole sole if the scaly pattern is present, not just the itchy part
- Usually one to two weeks for terbinafine; other antifungals need longer
- Keep going a few days past clearing — stopping the moment it looks better is the classic route to recurrence
- Dry properly between the toes after washing, before applying anything
If the skin is very macerated and soggy between the toes, keeping it dry matters as much as the cream — a wisp of dry cotton wool between the toes, or simply separating them while the feet air, makes a real difference.
Shoes and socks
Footwear is the second reservoir, and it is the one nobody deals with.
| Item | What to do |
|---|---|
| Socks | Change daily, wash hot, and choose materials that move moisture rather than hold it |
| Shoes | Rotate so each pair has at least 24 hours to dry out fully. Alternating two pairs beats wearing one pair every day |
| Old shoes | Consider replacing the pair worn constantly throughout an infection — particularly trainers |
| Antifungal powder or spray | Into shoes, which addresses what cream on the feet cannot |
| Communal areas | Flip-flops in changing rooms, showers and around pools, both to avoid catching it and to avoid passing it on |
Stopping it spreading
- Do not share towels, and wash them frequently at a hot temperature
- Use a separate towel for the feet, and dry the feet last
- Do not share nail clippers or files, and use a separate file for infected nails and discard it
- Do not walk barefoot around the house while the infection is active if others are susceptible
- Treat everyone affected at once — passing it back and forth within a household is common
The complication worth knowing about
Cracked, fissured skin between the toes is a route for bacteria into the leg. Athlete's foot is a recognised precipitant of cellulitis — a spreading bacterial infection of the skin and tissue beneath. Seek urgent advice for a red, hot, swollen, painful area spreading up the foot or leg, particularly with fever or feeling unwell.
This is a bigger consideration than the cosmetic one, and it is the main reason athlete's foot is worth treating properly in people with diabetes, poor circulation, leg swelling or a previous episode of cellulitis, rather than tolerating it.
It spreads beyond the feet
- The groin — jock itch is frequently the same infection transferred from the feet, classically by pulling underwear on over infected feet. Put socks on before underwear if you have both
- The hands — usually one hand, from scratching the feet
- The body — ringworm, as expanding rings with a raised scaly edge and a clearer centre
- The nails — the reason this guide exists
All are treated with antifungal cream, though the groin and body clear considerably faster than feet.
Preventing recurrence
Recurrence is common, and almost always comes from the same few sources:
| Source | Fix |
|---|---|
| Infected nails | Treat them — see treatments compared. An untreated nail reinfects skin indefinitely |
| Shoes | Rotate, dry, powder, replace the worst offenders |
| Stopping cream too early | Continue a few days past clearing |
| Damp feet all day | Better socks, breathable shoes, drying between the toes |
| Communal floors | Flip-flops |
| Someone else in the house | Treat everyone at the same time |
Get assessed rather than self-treating if you have diabetes, poor circulation or a weakened immune system; the foot is painful, swollen or discharging; the skin is broken and spreading redness is developing; or the infection has not responded to two weeks of appropriate treatment.
Frequently Asked Questions
Does athlete's foot cause fungal nails?
Frequently, yes. It is usually the same organism in two places, and fungus on the skin between the toes spreads under the nail. Once the nail is infected it seeds back onto the skin indefinitely, which is why both need treating together.
How long does athlete's foot take to clear?
Usually one to two weeks with terbinafine cream, though other antifungals need longer. Continue for a few days after the skin looks normal, because stopping the moment it looks better is the commonest reason it returns.
Do I need to throw away my shoes?
Not necessarily, but footwear is a genuine reservoir. Rotate shoes so each pair dries out fully for at least 24 hours, use an antifungal powder or spray inside them, and consider replacing a pair worn constantly throughout an infection, particularly trainers.
Can athlete's foot be dangerous?
It can lead to complications. Cracked skin between the toes is a route for bacteria into the leg, and athlete's foot is a recognised precipitant of cellulitis. Seek urgent advice for a red, hot, swollen area spreading up the foot or leg, especially with fever, and treat it promptly if you have diabetes, poor circulation or leg swelling.
Why does my athlete's foot keep coming back?
Usually an untreated fungal nail acting as a reservoir, shoes that were never dealt with, or stopping the cream as soon as the skin looked better. Someone else in the household carrying it is another common reason, which is why treating everyone at the same time helps.
References
- NHS. Fungal nail infection. nhs.uk
- NHS. Athlete's foot. nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Fungal nail infection. cks.nice.org.uk
- DermNet. Fungal nail infections. dermnetnz.org
- National Institute for Health and Care Excellence. Suspected cancer: recognition and referral (NG12). nice.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. An abnormal nail is not always a fungal infection, and a new dark streak in a nail should always be assessed. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.