Chlorine bleach and heat are the two most reliable ways to kill ringworm spores. The fungal spores that cause ringworm can survive on surfaces, fabrics, and household items for 12 to 20 months, which is why cleaning up after an infection matters just as much as treating the skin itself. Here’s what actually works, what doesn’t, and how to apply each method.
Why Ringworm Spores Are Hard to Kill
Ringworm isn’t a worm. It’s a fungal infection caused by dermatophytes, a group of fungi that feed on keratin in skin, hair, and nails. These fungi produce spores (called conidia) that are remarkably durable. They shed onto clothing, bedding, floors, furniture, and pet areas, then sit there for up to 20 months waiting to contact skin again. That’s why reinfection is so common, especially in households with pets. Killing the spores in your environment is a necessary step to break the cycle.
Bleach: The Most Effective Option
Diluted household bleach is consistently the top performer against dermatophyte spores on hard surfaces. Veterinary dermatology guidelines, which deal with some of the most stubborn ringworm outbreaks in shelters and catteries, confirm that chlorine bleach is one of only two disinfectants rated “very effective” at environmental decontamination.
Most household bleach contains 5% to 9% sodium hypochlorite. A 1:10 dilution (one part bleach to nine parts water) is the standard recommendation for ringworm cleanup. The CDC advises leaving any bleach solution on a surface for at least one minute of contact time before wiping, though longer contact is better for porous or heavily contaminated areas. Use it on hard floors, countertops, bathroom tiles, sinks, and any non-porous surface the infected person or animal has touched. Bleach will damage wood finishes, colored fabrics, and some plastics, so test a small area first or choose an alternative for those materials.
Laundry: Temperature Is Everything
Washing contaminated clothing, towels, and bedding at 60°C (140°F) or higher eliminates dermatophyte spores. A 2022 study in the Journal of Fungi tested three common species of ringworm fungi on fabric and found that every sample washed at 60°C or 90°C came out completely clean. Every sample washed at 40°C (104°F), which is a typical “warm” cycle, still grew dermatophytes within days.
That 60°C threshold is critical. During the study’s 60°C wash cycle, the machine only actually reached that temperature for about 8 out of 100 minutes, yet it was still enough to destroy the spores. If your washer has a “hot” or “sanitize” setting, use it for anything that touched the infection: sheets, pillowcases, socks, underwear, towels, and washcloths. For items that can’t tolerate hot water, soaking in a diluted bleach solution before washing is an alternative.
Quaternary Ammonium Disinfectants
Quaternary ammonium compounds (often labeled “quats” on cleaning products) can kill ringworm spores, but they need far more time than bleach. In a controlled trial, researchers soaked dermatophyte-contaminated sock fabric in a 0.3% quaternary ammonium solution. After 30 minutes and even 2 hours, some fungi survived. Only after a full 24-hour soak did the disinfection rate hit 100%.
This makes quats a reasonable option for pre-soaking laundry you can’t bleach or wash at high temperatures, but they’re not practical for quick surface cleaning. If you’re using a quat-based product on hard surfaces, expect to need extended contact time well beyond the usual spray-and-wipe approach.
UV-C Light
Ultraviolet light in the UV-C range (230 to 280 nanometers) does kill ringworm spores, but effectiveness depends on the dose. The UV-C energy needed varies by species. Spores of Trichophyton rubrum, one of the most common causes of ringworm in humans, require a median dose of about 28 mJ/cm² in liquid. Trichophyton tonsurans, which causes scalp ringworm in children, needs roughly 59 mJ/cm². Microsporum canis, the species most often spread by cats, requires about 20 mJ/cm².
Consumer UV-C wands and sanitizing devices exist, but most don’t publish their output in comparable units, making it hard to know whether they deliver enough energy. UV-C also only works on surfaces the light directly hits. It can’t penetrate fabric folds, carpet fibers, or shadowed areas. It’s a useful supplement to chemical disinfection but not a replacement.
What Doesn’t Work Well
Hydrogen peroxide at the standard 3% household concentration has very low antifungal activity. A study published in the Turkish Journal of Medical Sciences found that 3% hydrogen peroxide showed essentially no fungicidal effect under standard testing conditions, even with 5 minutes of contact time. Organisms that produce the enzyme catalase, which includes many fungi, break down hydrogen peroxide into water and oxygen before it can do damage. Higher concentrations and much longer contact times would be needed, putting it well outside practical household use.
Vinegar is another popular suggestion that falls short. Research shows household vinegar (4% to 5% acetic acid) can inhibit certain mold species, but its effects are inconsistent across different fungi. It showed no activity at all against some species tested, and its lack of persistence on surfaces limits even its partial effects to non-porous materials. Vinegar may slow fungal growth in some cases, but there’s no evidence it reliably kills dermatophyte spores.
Rubbing alcohol (70% isopropyl alcohol or ethanol) also performed poorly in antifungal testing. It evaporates quickly, giving it very little contact time with spores on a surface.
How to Clean an Infected Home
Start with the high-contact areas: bathroom floors, shower stalls, sinks, and any surfaces the infected person or pet regularly touches. Vacuum carpets and upholstered furniture thoroughly to physically remove shed spores before disinfecting hard surfaces with diluted bleach. Dispose of the vacuum bag or empty the canister outside.
Wash all bedding, towels, and clothing that contacted the infection at 60°C or higher. If you have items that can’t be washed hot, soak them in a diluted bleach or quaternary ammonium solution for an extended period before laundering. Change towels and bedding frequently during active treatment, and don’t share them between household members.
For households with an infected pet, the cleanup becomes more intensive. Veterinary guidelines recommend thorough environmental disinfection every four to six weeks alongside the animal’s treatment. Enilconazole, a veterinary antifungal spray, is rated alongside bleach as one of the only highly effective environmental treatments, though it’s typically only available through a vet. In single-pet homes, keep in mind that by the time you notice the infection, everyone in the household has likely already been exposed, so treatment of the animal matters as much as environmental cleaning.
Smooth, non-porous surfaces are easy to decontaminate. Porous materials like carpet, fabric furniture, and cardboard are much harder because spores embed in fibers where disinfectants can’t fully reach. In severe or recurring cases, replacing heavily contaminated porous items may be more effective than repeated cleaning.