You kill a fungus by destroying its cell membrane, starving it of moisture, or exposing it to chemicals or heat that break it apart. The right method depends on where the fungus is: on your body, on a surface in your home, or embedded in materials like wood or drywall. Each situation calls for a different approach, and some fungi are far harder to kill than others.
How Antifungal Treatments Work
Fungi build their cell walls using a fatty molecule called ergosterol, which is different from the cholesterol in human cells. Most antifungal drugs exploit this difference. The most common class, called azoles, blocks a key enzyme the fungus needs to produce ergosterol. Without it, the cell membrane becomes leaky, and the fungal cell eventually ruptures and dies.
A second class, called allylamines (the active ingredient in many over-the-counter creams), hits a different step in the same pathway. In head-to-head comparisons, allylamines maintain a cure for longer periods than azoles, meaning the infection is less likely to bounce back after treatment ends. This distinction matters most for stubborn skin infections like athlete’s foot or jock itch, where recurrence is common.
Treating Fungal Infections on Your Body
Most skin-level fungal infections, including ringworm, athlete’s foot, and yeast-based rashes, respond to topical creams or sprays you can buy without a prescription. These typically contain either an azole (like clotrimazole or miconazole) or an allylamine (like terbinafine). You apply them directly to the affected area, usually once or twice a day for two to four weeks. The visible rash often clears before the fungus is fully dead, so finishing the full course matters.
Nail fungus and deeper infections are a different story. Topical treatments struggle to penetrate the nail plate, so oral medication is often necessary. Oral antifungals are effective but carry a small risk of liver stress. Doctors typically check liver function before starting a course and sometimes during treatment, though the actual risk of serious liver injury is low. The average time from starting treatment to any sign of a problem is about 33 days, which is why those early check-ins exist.
Tea Tree Oil as a Natural Option
Tea tree oil does have real antifungal activity. Lab studies show it inhibits common skin fungi (dermatophytes) at concentrations as low as 0.11%, and yeast species like Candida at around 0.22% to 0.44%. That’s a very low concentration, which is why diluted tea tree oil can work as a supplementary treatment for mild skin infections. It’s not a replacement for proven antifungals in moderate or severe cases, but for minor athlete’s foot or surface-level yeast issues, it’s a reasonable first step.
Killing Mold and Fungus on Household Surfaces
For mold on hard surfaces like countertops, tile, glass, sinks, and shower walls, a bleach solution is the standard recommendation. The CDC advises mixing 1 cup (240 mL) of bleach into 1 gallon of water. Scrub the surface with this mixture, using a stiff brush on rough or textured areas, then rinse with clean water and let it air dry. Wear gloves, goggles, and a mask while you work, since both bleach fumes and disturbed mold spores can irritate your lungs and skin.
Hydrogen peroxide (the standard 3% concentration sold in drugstores) is a good alternative for people who want to avoid bleach. It works well on solid, non-porous surfaces. The trade-off is that it can bleach natural fabrics like wool and some colored materials, and it won’t penetrate porous surfaces like bare wood or fabric effectively. If mold has soaked into drywall, carpet padding, or unfinished wood, surface cleaning alone won’t solve the problem. Those materials usually need to be removed and replaced.
Controlling Humidity to Prevent Growth
Fungi need moisture to grow. The EPA recommends keeping indoor relative humidity below 60%, with an ideal range of 30% to 50%. Above 60%, condensation forms on cooler surfaces like window frames, pipes, and exterior walls, giving mold exactly what it needs to colonize. A simple hygrometer (available for a few dollars at hardware stores) lets you monitor your levels.
Practical steps include running exhaust fans in bathrooms and kitchens, fixing leaks promptly, venting clothes dryers to the outside, and using a dehumidifier in damp basements. If you’ve had a flood or major water intrusion, drying the area within 24 to 48 hours is critical. After that window, mold colonization becomes much more likely on any wet organic material.
Using Heat to Kill Fungus
Heat is effective against fungi, but the temperatures required vary widely depending on whether you’re dealing with active growth or dormant spores. Spores are the tough, seed-like survival structures that let fungi recolonize after cleaning. General dry heat treatment at 140°C (284°F) for about 3 hours, or 180°C (356°F) for 15 minutes, is enough to sterilize contaminated surfaces. At 400°C, spores die in 20 to 30 seconds.
For everyday purposes, this means your oven, a steam cleaner, or a hot wash cycle can help. Washing contaminated clothing or linens at the hottest setting your fabric can tolerate, then running them through a hot dryer, kills most active fungal growth. It won’t necessarily sterilize every last spore on heavily contaminated items, but for routine laundry after a skin infection, it’s effective.
UV Light as a Disinfection Tool
UV-C light at a wavelength of 254 nanometers (the type used in germicidal lamps) damages fungal DNA and can kill both active cells and spores. However, the dose required varies enormously by species. Yeast cells on a surface can be knocked down with a relatively low dose of about 2.2 millijoules per square centimeter. But the spores of tougher molds like Aspergillus niger require over 100 millijoules per square centimeter in liquid, and over 448 millijoules on solid surfaces. That’s roughly 50 to 200 times more energy.
Consumer-grade UV-C wands and boxes exist, but their actual output and exposure time rarely match what’s needed for resistant mold spores. They can be useful as a supplementary measure, particularly against yeast and lighter fungal contamination, but they’re not a substitute for physical cleaning and chemical treatment on visibly moldy surfaces.
Why Some Fungi Are Harder to Kill
Not all fungi are equally vulnerable. Yeasts like Candida are single-celled and relatively fragile. Dermatophytes (the fungi behind athlete’s foot and ringworm) are tougher but still manageable with topical treatment. Molds like Aspergillus produce dense spore structures that resist heat, UV light, and chemical treatment far better than their active growing forms. This is why mold remediation often requires removing contaminated building materials entirely rather than just cleaning them.
Fungal biofilms, where colonies embed themselves in a protective matrix on surfaces, add another layer of difficulty. Biofilms can be 10 to 1,000 times more resistant to antifungal agents than free-floating cells. Scrubbing physically disrupts the biofilm, which is why the CDC’s mold-cleaning instructions emphasize using a stiff brush rather than just spraying and wiping.