Toenail fungus, medically known as onychomycosis, is a common infection caused by dermatophytes, microscopic fungi that feed on keratin found in nails and skin. When an infection occurs, many people worry that the fungus has contaminated their footwear and that shoes must be discarded to prevent reinfection. While throwing away shoes can be stressful and expensive, the primary goal is usually sterilization of the shoe environment to break the cycle of fungal return, not disposal.
The Role of Footwear in Fungal Reinfection
Fungi thrive in warm, dark, and moist environments, making the inside of a shoe a perfect habitat. Footwear traps sweat and heat, creating a humid microclimate that encourages dermatophyte growth. Fungal spores are shed from the infected nail or skin into the shoe lining and insoles.
These resilient spores can survive in the shoe environment for months, potentially up to two years, remaining dormant until conditions are right to cause a new infection. Keratin-rich debris, such as shed skin cells and nail fragments, provides a food source, allowing the fungus to persist even after the initial infection is treated. This makes footwear a significant reservoir for reinfection, making sanitation a necessary part of treatment.
When Throwing Away Footwear is Necessary
For the majority of shoes, throwing them away is unnecessary because proper sanitation methods are highly effective. Most footwear can be successfully disinfected and retained. However, disposal becomes the most practical option in certain exceptions to ensure the infection cycle is fully broken.
Old shoes that are heavily worn, permanently damp, or severely compromised by the infection should be discarded. Footwear made from non-breathable synthetic materials, which perpetually trap moisture, or cheap items like plastic flip-flops that cannot be effectively cleaned or aired out, should also be replaced. Shoes worn extensively without socks during the active infection are more likely to have deep contamination in the porous lining, making them harder to sanitize thoroughly. Finally, if a shoe causes a mechanical pressure point that consistently damages the nail, leading to recurring infections, replace it with a better-fitting option.
Effective Methods for Shoe Sanitation
Addressing the fungal reservoir requires combining drying, chemical, and physical methods to eliminate spores. Since fungi require moisture, the first step is ensuring shoes are thoroughly dry by alternating pairs to allow 24 hours of drying time between wears. Specialized shoe dryers using heat or UV light are effective, as ultraviolet light eliminates fungi inside the shoe.
Chemical treatment focuses on killing dermatophytes directly. Apply over-the-counter antifungal sprays or powders, containing active ingredients like miconazole or zinc oxide, to the inside of the shoe, especially the insole, following product instructions. For washable shoes, such as sneakers, washing them in hot water (at least 140°F or 60°C) can kill fungal cells. Focus cleaning on the inner surfaces where fungi are most concentrated.
Preventing Future Fungal Growth
After sanitizing existing footwear, maintaining a dry and clean environment is essential to preventing infection recurrence. A regular rotation of shoes is the simplest and most effective habit, ensuring no single pair is worn two days in a row. This allows time for complete aeration and drying.
Storing shoes in a well-ventilated space, rather than a dark, damp closet, further discourages fungal proliferation. Opting for shoes made of breathable materials like canvas or leather allows for better airflow around the foot, reducing moisture. Always wear moisture-wicking socks, such as synthetic blends, and change them immediately if they become damp or sweaty. Daily application of an antifungal or moisture-absorbing powder inside the shoe creates an inhospitable environment for stray fungal spores.