How to Kill Athlete’s Foot Fungus in Shoes

Athlete’s foot fungus can survive inside shoes for weeks, sometimes months, clinging to insoles, linings, and seams even when your feet are feeling fine. Killing it takes deliberate action because the warm, damp interior of a shoe is close to ideal for fungal growth. Several disinfection methods genuinely work, from chemical sprays to UV-C light devices, but a few popular home remedies, including the widely repeated freezer trick, turn out to be surprisingly ineffective.

Why Your Shoes Keep Reinfecting You

The dermatophytes responsible for athlete’s foot, most commonly a species called Trichophyton rubrum, thrive in warm, humid, low-airflow environments. That description fits the inside of a closed-toe shoe almost perfectly. Research measuring the microclimate inside footwear has found a clear relationship: the higher the temperature and humidity, and the lower the ventilation, the more microbial growth occurs on the skin of the foot.¹ A separate study confirmed that people wearing shoes with high-temperature, high-humidity interiors had a significantly higher incidence of athlete’s foot, and that the internal conditions of footwear shift with season.²

The problem is not just that fungus lands in your shoe while you have an active infection. It is that the fungus stays viable after you kick the shoes off. A study that cultured dust from the safety shoes of workers with athlete’s foot found live Trichophyton in roughly 40% of the shoes tested.³ This means you can finish a full course of antifungal cream, clear the infection on your skin, and then reinfect yourself the next morning by slipping on the same pair of sneakers. Treating the shoes, not just the feet, is a genuine part of breaking the cycle.

What Freezing and Tumble Drying Will Not Do

The advice to bag your shoes and leave them in the freezer overnight shows up constantly online. It sounds reasonable: extreme cold should kill living organisms. But dermatophytes are tougher than that. In a controlled laboratory study, contaminated materials exposed to −20°C (about the temperature of a household freezer) for 24 hours, 48 hours, and even a full week all still grew fungus afterward when cultured.⁴ The fungal spores essentially go dormant in the cold and wake right back up at room temperature.

Tumble drying is similarly disappointing. The same study put contaminated pads through domestic and commercial dryers, and every sample came back positive for dermatophytes within a week of being cultured.⁴ Perhaps most surprising, direct dry heat at 60°C for up to 90 minutes also failed to eliminate the fungus.⁴ Dry heat alone, even at fairly high temperatures and for extended periods, is not enough. The spores that dermatophytes produce are remarkably resistant to environmental stress, which is part of why these infections are so persistent.

Low-temperature washing is also ineffective as a standalone approach. Washing at 30°C for a 10-minute main cycle does not inactivate dermatophyte spores, though it can kill Candida species.⁵ A regular cold or warm wash of your socks and removable insoles might feel hygienic, but it is not fungicidal.

Hot-Water Laundering for Washable Items

If the ineffective methods share a theme, it is that they do not combine enough heat with enough time in the right conditions. Hot-water laundering is the exception. Washing at 60°C or above for a main cycle of at least 45 minutes has proven effective at eliminating dermatophytes and Candida from contaminated fabrics.⁵ In a separate experiment, contaminated materials laundered at 60°C for 100 minutes showed no dermatophyte growth at all, with or without detergent.⁴

The practical limitation is obvious: most shoes cannot go in a washing machine at 60°C without being destroyed. Canvas sneakers and some running shoes with removable insoles might tolerate it. Leather, suede, and most dress shoes will not. But this finding has real value for socks, removable insoles, and cloth liners. If you are dealing with a recurring infection, washing these items on a hot cycle is one of the few proven home methods. And the fact that detergent made no difference in the lab results means the temperature itself is doing the work, not the soap.

Microwave Treatment for Removable Insoles

Microwaving sounds unconventional, but it has laboratory backing. Researchers tested microwave irradiation on polyethylene sponge insoles and cork insoles contaminated with four different dermatophyte species. Complete growth inhibition of all four species on both insole types occurred after 30 seconds of exposure at 560 watts, which brought the internal temperature to about 60°C.⁶

This is a striking contrast with the dry-heat results discussed earlier, where 60°C for 90 minutes was not enough. The likely explanation is that microwave radiation does not just heat the surface. The electromagnetic waves penetrate the material and heat it from the inside out, and the rapid temperature change appears more lethal to fungal spores than a slow external bake. There were differences between dermatophyte species in how vulnerable they were at lower power settings, but at 560 watts for 30 seconds, all four were wiped out.

A few cautions if you try this at home: only microwave insoles that contain no metal components, no glue-backed foil, and no gel inserts. Rubber-backed insoles can melt. Thin foam or fabric insoles are the safest candidates. And never microwave an entire shoe. The metal eyelets, reinforced heels, and mixed-material construction of most shoes will either spark, melt, or catch fire.

UV-C Light Sanitizer Devices

UV-C shoe sanitizers are commercially available devices, typically shaped like inserts that you slide into your shoes and leave running for a set period, usually 15 to 45 minutes. They emit shortwave ultraviolet light at a wavelength around 254 nanometers, which damages the DNA of microorganisms and prevents them from reproducing. Research using a controlled shoe-infection model with Trichophyton rubrum and Trichophyton mentagrophytes, the two most common athlete’s foot dermatophytes, has shown significant reductions in fungal contamination in both athletic and leather shoes after UV-C treatment.

UV-C devices have an advantage over most other methods in that they work inside the shoe without getting it wet, heated to a destructive temperature, or coated in chemicals. The limitation is reach. UV-C light travels in straight lines, so deep creases, folds in the tongue, and the underside of lacing systems may not get adequate exposure. The devices also have no residual effect: they kill what the light touches during the treatment, but they do not leave behind anything that continues to suppress fungal growth afterward. Using them after every wear is more effective than occasional use.

Ozone Gas

Ozone is a powerful oxidizer that destroys microorganisms by breaking down their cell walls. A study testing ozone gas on footwear contaminated with fungi from onychomycosis (fungal nail infection) patients found it was effective at sanitizing the shoes.⁷ Unlike UV light, ozone is a gas, so it can reach into seams, under insoles, and around irregular surfaces that light cannot hit directly.

Home ozone generators designed for shoes are available, though they are less common and more expensive than UV devices. The drawback is that ozone in high concentrations is irritating to the lungs and mucous membranes. These devices should only be used in well-ventilated areas, and you should not breathe the gas during treatment. The shoes also need to air out for a period afterward before wearing them.

Antifungal Sprays and Powders

Over-the-counter antifungal sprays marketed for shoes typically contain active ingredients like tolnaftate, miconazole, or undecylenic acid. Spray-on disinfectants like Lysol, which contain quaternary ammonium compounds or ethanol, are also commonly recommended. These products work by chemical contact: you spray the interior of the shoe, the chemical kills or inhibits the fungus it touches, and the shoe is left to dry. The advantage is convenience and cost. A can of antifungal spray is cheap, widely available, and will not damage most shoe materials.

The main limitation is penetration. A surface spray reaches the lining and the top of the insole, but dermatophyte spores can embed in foam, stitching, and deeper layers of porous materials. A single application might knock down the surface fungal load without sterilizing the shoe completely. For this reason, consistent daily use over the course of an active infection and for several weeks afterward tends to work better than a one-time treatment. Spraying shoes at night and letting them dry open overnight gives the chemicals more contact time and allows moisture to evaporate.

Antifungal foot powders, often containing miconazole or tolnaftate, take a slightly different approach. Rather than killing fungi in the shoe material itself, they absorb moisture and create a less hospitable surface. This is more of a suppression strategy than a kill method, but it complements the other approaches well. Sprinkle powder into the shoe before wearing and you reduce the humidity that fungi need.

One thing worth noting: some shoe deodorizer and antimicrobial sprays contain concentrated quaternary ammonium compounds or other chemicals that can cause contact dermatitis in sensitive individuals. If you develop itching, redness, or a rash on the tops of your feet or around the ankle after using a new shoe spray, the spray itself might be the culprit rather than a worsening fungal infection. Switching to a different product or rinsing the shoe interior with water and allowing it to dry fully before wearing can resolve the issue.

Shoe Rotation and Drying Strategy

No single treatment session will matter much if you put damp shoes back on the next morning. Given that higher in-shoe humidity directly correlates with more microbial growth on foot skin,¹ one of the most effective long-term strategies is also one of the simplest: rotate your shoes so each pair gets at least 24 to 48 hours to dry out between wears.

This does not kill the fungus by itself, but it degrades the environment the fungus needs to flourish. A shoe that dries fully between wears has lower humidity when you put it back on, and the foot stays drier for longer. Pulling insoles out after each wear speeds up drying. Stuffing shoes with newspaper or using cedar shoe trees can wick moisture further.

Footwear material matters, too. Research has consistently identified poor ventilation as a driver of in-shoe humidity and subsequent fungal risk.² Mesh-upper running shoes dry faster and breathe better than synthetic leather or rubber boots. If your work or lifestyle demands closed, non-breathable shoes, rotation becomes more important, not less.

Antimicrobial Insoles and Coatings

A newer approach targets the shoe interior with built-in antimicrobial technology. Insoles treated with quaternary ammonium silane coatings, applied using a sol-gel technique, have been tested in the lab and showed substantial bacteria reduction, in the range of 92 to 96 percent after 24 hours of contact.⁸ These coatings bond to the insole material and remain active over time rather than washing off after a few uses.

Most commercially available antimicrobial insoles use silver-ion technology, copper-infused fibers, or activated charcoal, and the evidence behind each varies. Silver-ion insoles have the most published support for broad antimicrobial activity, though most studies test bacteria rather than dermatophytes specifically. If you are shopping for antimicrobial insoles to manage recurring athlete’s foot, look for products that specify antifungal testing, not just antibacterial claims. The two categories of organisms respond to different mechanisms, and a product that suppresses odor-causing bacteria may do nothing to dermatophyte spores.

Treating the Feet and the Shoes at the Same Time

Shoe treatment alone will not cure an active infection. The fungus lives in the skin, and clearing it requires a topical antifungal applied directly to the feet, sometimes for several weeks. But treating only the feet while ignoring contaminated footwear creates a reinfection loop, as the research on viable Trichophyton in shoe dust confirms.³ The most effective approach runs both tracks in parallel: antifungal medication on your skin and disinfection of every pair of shoes you have worn during the infection.

An aromatic essential-oil compound tested in a case study showed that applying it to the external surfaces of the feet completely inhibited aerobic bacteria and yeast-fungi-mold growth for eight hours, even inside enclosed footwear.⁹ That is a small study and not a substitute for proven antifungals, but it points toward the value of addressing the foot surface directly as a complement to shoe sanitation. Keeping the skin of the foot inhospitable to fungus, through topical treatments, thorough drying after bathing, and moisture-wicking socks, reduces the fungal load being deposited into the shoe each day.

Putting a Practical Routine Together

With so many methods available, the practical question is which combination actually fits into daily life. Here is a reasonable approach ranked by effort and evidence:

Daily minimum: After removing shoes, pull insoles out and let both dry in open air. Spray the interior with an over-the-counter antifungal shoe spray. Rotate to a different pair the next day.
Weekly: Wash socks and removable insoles at 60°C or hotter for at least 45 minutes. If your insoles are microwave-safe foam, a 30-second burst at medium-high power offers a faster alternative.
During active infection: Treat every pair of recently worn shoes, not just the one you suspect. Use a UV-C device nightly if you have one, or spray-treat each pair and leave them open to dry. Continue shoe treatment for at least two weeks after your skin symptoms clear.
For stubborn or recurring cases: Consider replacing insoles entirely. An ozone device or UV-C sanitizer used consistently adds a layer of protection that spray alone cannot match. Antimicrobial replacement insoles reduce the ongoing fungal load between treatments.

The methods that do not work are worth remembering, too, because they waste time during which the fungus continues to thrive. Freezing your shoes for a night or tossing them in the dryer gives a false sense of having dealt with the problem. Even a full day and a half at −20°C leaves dermatophyte spores ready to grow the moment conditions warm up.⁴ Stick with the methods that have laboratory evidence behind them, and apply them consistently rather than once in a burst of motivation.

When to Replace the Shoes Entirely

There is a point at which treating a pair of shoes is not worth the effort. Shoes with heavily deteriorated linings, cracked or crumbling foam insoles, or persistent odor despite repeated treatment are essentially reservoirs of embedded spores that no surface spray or UV device can fully reach. If you have been through a complete course of antifungal medication, treated your shoes consistently, and the infection still comes back, the shoes themselves may be the weak link. Replacing them and starting fresh with the disinfection habits described above is sometimes the most practical decision.

This is especially true for athletic shoes and work boots that see heavy daily use. The combination of sweat absorption over months, compressed foam that traps moisture, and porous materials that harbor spores deep inside makes older shoes progressively harder to sanitize. It is not a failure of the disinfection method; it is a material-science reality. A shoe that has soaked up thousands of hours of foot sweat has a microbial ecology that surface treatments can only partly address. Treating the replacement pair from day one, with rotation, spray, and proper drying, is far more effective than trying to rescue a shoe that has been a fungal habitat for years.

1
PubMed Central. Footwear microclimate and its effects on the microbial community of the plantar skin
2
PubMed Central. Internal environment of footwear is a risk factor for tinea pedis
3
Drug Discoveries & Therapeutics. Detection of Trichophyton spp. from footwear of patients with tinea pedis
4
PubMed Central. Effect of Household Laundering, Heat Drying, and Freezing on the Survival of Dermatophyte Conidia
5
PubMed Central. Hygiene Practices Against Dermatophytic Fungi: A Review of Strategies to Combat Antifungal Resistance
6
PubMed. The effect of microwave irradiation on the vitality of various dermatophytes
7
PubMed. Sanitization of contaminated footwear from onychomycosis patients using ozone gas: a novel adjunct therapy for treating onychomycosis and tinea pedis?
8
DergiPark (Turkish Journal of Bioscience and Collections). Antibacterial Efficiency of Quaternary Ammonium Silane-Coated Shoe Insoles Using the Sol-Gel Technique
9
PubMed Central. A novel aromatic oil compound inhibits microbial overgrowth on feet: a case study