The fungus that causes athlete’s foot can survive inside your shoes for weeks or even months, reinfecting your feet every time you slip them on. Killing it requires either heat above 140°F (60°C), a chemical disinfectant with enough contact time, or a combination of both. Simply airing shoes out or tossing them in the freezer won’t do it. Here’s what actually works.
Why Fungal Spores Survive So Long in Shoes
The fungi behind athlete’s foot, mainly a group called dermatophytes, produce tiny spores that are built to last. They thrive in warm, dark, moist environments, which describes the inside of a worn shoe perfectly. Even after your feet dry out, those spores cling to the insole, lining, and stitching, waiting for the next burst of warmth and sweat to start growing again.
This is the main reason athlete’s foot keeps coming back after treatment. You clear the infection on your skin, put on the same shoes, and pick it right back up. Treating your feet without treating your footwear is like mopping the floor while the faucet is still running.
Hydrogen Peroxide: The Most Effective DIY Option
A 0.5% hydrogen peroxide solution achieved 100% kill rates against dermatophyte spores on contaminated textiles in lab testing, as long as it had a 10-minute contact time. That concentration is weaker than the standard 3% bottles sold at drugstores, so you can dilute regular hydrogen peroxide roughly 6:1 with water and still hit the effective threshold.
To use it, mix the solution in a spray bottle and spray the inside of each shoe thoroughly, focusing on the toe box and insole. Let the shoes sit for at least 10 minutes before wiping them out and allowing them to air dry completely. Hydrogen peroxide is relatively gentle on materials, though it can lighten dark fabrics over time. Test a small hidden spot first on colored leather or suede.
Other Chemical Disinfectants That Work
Several chemical agents have broad antifungal activity against dermatophytes. Besides hydrogen peroxide, the main options include:
- Bleach (sodium hypochlorite): Effective but harsh. A diluted solution (roughly one tablespoon of household bleach per cup of water) can kill spores, but it may discolor or damage shoe materials. Best reserved for white sneakers or shoes you don’t mind roughing up.
- Isopropyl alcohol (rubbing alcohol): Spraying 70% isopropyl alcohol inside shoes kills many fungi on contact and evaporates quickly. It’s less likely to stain than bleach but can dry out leather over time.
- Commercial antifungal shoe sprays: Most contain undecylenic acid (typically at 10%) as their active ingredient, sometimes paired with tea tree oil or eucalyptus oil. These are convenient and formulated to be safe on shoe materials, but they generally need repeated daily use to keep fungal levels down rather than eliminating spores in one treatment.
Whichever product you choose, contact time matters more than the amount you spray. A light mist that evaporates in two minutes won’t do much. Saturate the interior and give it time to work.
Heat Treatment: Washing Machine and Dryer
For shoes that can handle a washing machine (canvas sneakers, athletic shoes, some synthetics), a hot wash is one of the most reliable methods. Research on dermatophyte spores shows that laundering at 140°F (60°C) eliminates them completely, while washing at 104°F (40°C) does not. Spores survived the lower temperature wash and resumed growing within days.
If your machine has a sanitize or hot cycle, use it. Follow with a full run in the dryer on high heat, which adds a second round of spore-killing temperatures. Remove insoles and wash them separately so water and heat can reach all surfaces.
This method isn’t suitable for leather, suede, or shoes with glued soles that may come apart in water. For those, stick with spray-based disinfection.
Why Freezing Your Shoes Doesn’t Work
You’ll find plenty of advice online suggesting you bag your shoes and put them in the freezer overnight. The logic sounds reasonable: extreme cold should kill the fungus. But dermatophyte spores are remarkably cold-tolerant. Freezing temperatures cause them to go dormant rather than die. Once the shoes warm back up, the spores resume activity as if nothing happened. The same research that confirmed heat kills spores at 140°F found that cold temperatures simply aren’t effective. Save your freezer space.
UV Shoe Sanitizers
UV-C light devices designed to fit inside shoes have become a popular option. These gadgets emit ultraviolet light at a wavelength that damages microbial DNA. In testing, one widely sold UV sanitizer reduced fungal levels by about 76% in shoes contaminated with dermatophytes. That’s a meaningful reduction, but it’s not complete elimination, and the study noted the results weren’t statistically different from control shoes in some conditions.
UV sanitizers work best as a maintenance tool, something you use regularly to keep fungal levels low, rather than a one-time fix for heavily contaminated shoes. They’re also limited by line-of-sight: UV light can’t reach deep into seams, folds, or the underside of a thick insole. Pairing a UV device with a chemical spray covers both limitations.
Preventing Recontamination
Once you’ve disinfected your shoes, the goal is keeping them from becoming a fungal breeding ground again. A few practical habits make a significant difference.
Rotate your shoes so no single pair is worn two days in a row. This gives each pair at least 24 hours to dry out fully between wears. Fungal spores need moisture to grow, and breaking that cycle slows them considerably. If you sweat heavily, stuff shoes with newspaper or cedar shoe trees after wearing them to pull moisture out faster.
Moisture-wicking socks help keep your feet drier inside the shoe. Copper-impregnated socks go a step further. In a clinical trial with 300 soldiers, copper oxide socks used as the only treatment reduced scaling by 44% and cleared vesicular eruptions by 63% within three weeks. The socks performed comparably to prescription antifungal medication for controlling cracking and blisters. They won’t replace disinfecting your shoes, but they add a layer of ongoing protection.
Removable insoles are worth the small investment. You can pull them out after each wear to dry separately and spray them down or replace them periodically. Most of the fungal load concentrates on the insole surface where your foot makes direct contact.
What to Do With Heavily Contaminated Shoes
If you’ve been dealing with a stubborn, recurring athlete’s foot infection, your oldest everyday shoes may not be worth saving. Porous materials like fabric linings and foam insoles absorb sweat and fungal spores deep into their structure, where sprays and UV light can’t fully reach. In that case, replacing the shoes (or at minimum the insoles) while you treat your feet gives you the cleanest start. For shoes you want to keep, combine methods: spray with hydrogen peroxide, let them dry completely, then follow up with a UV sanitizer or antifungal spray on an ongoing basis.