Some methods of prevention include avoiding walking barefoot in public showers, keeping the toenails short, wearing big enough shoes, and changing socks daily.[4][5] When infected, the feet should be kept dry and clean and wearing sandals may help.[3] Treatment can be either with antifungal medication applied to the skin such as clotrimazole or for persistent infections antifungal medication that are taken by mouth such as terbinafine.[2][4] The use of the cream is typically recommended for four weeks.[4]
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

For more severe cases, oral antifungal medications might be required. These include fluconazole (an antifungal agent also commonly used to treat thrush), terbinafine (a broad-spectrum antifungal) and griseofulvin (usually used for skin infections). The latter is a very old drug and carries the risk of causing damage to the liver. Terbinafine is most effective and therefore is the preferred oral treatment. A 12-week course cures 70-80% of cases by causing the fungi’s cells to leak and die. It can, however, cause gastrointestinal side effects and depression.
Whitish or yellowish nails can occur due to onycholysis. This means separation of the nail from the nail bed. The color you see is air beneath the nail. The treatment is to trim the nail short, don't clean under it, polish if you want to hide the color, and wait two to three months. Persistent onycholysis can make the nails susceptible to fungal infection.
Nail infections occur more often in men than in women, and the infections are found in adults more often than in children. If you have family members who often get these types of fungal infections, you’re more likely to get them as well. Older adults are at the highest risk for getting fungal infections of the nails because they have poorer circulation and their nails grow more slowly and thicken as they age.
Readily available over-the-counter treatments work well for most nail-bed infections, especially early cases. An advanced toenail fungus infection may require a podiatrist’s intervention. To counteract a serious infection, medical professionals may utilize prescription topical medications, oral medications, and even laser therapy.  Some cases best respond to combination therapy.
Since some people are simply more prone to fungal infections, they are also prone to repeated infection. Preventive measures include keeping your feet clean and dry, avoiding prolonged moist environments, using socks in airport security lines, removing shoes, and allowing the feet skin to "breathe," avoiding walking barefoot, especially in public areas like swimming pools and gyms, avoiding contact with known infected people, and avoiding soaking and contaminated tool usage at nail salons. Weekly applications of a topical antifungal foot cream or sprinkling of antifungal foot powder (Zeasorb Foot Powder) into shoes may also be helpful.
Multiple fungi species can infect the nail. Fungus grows well in warm, moist environments such as showers. Fungus infection is one of the few foot problems that affect more men than women, perhaps because more men walk barefoot in locker rooms. Age is a factor, too. Half the sufferers are people older than 70. Other risk factors include having certain medical conditions such as diabetes, vascular insufficiency and malnutrition.
Trichophyton rubrum is the most common dermatophyte involved in onychomycosis. Other dermatophytes that may be involved are T. interdigitale, Epidermophyton floccosum, T. violaceum, Microsporum gypseum, T. tonsurans, and T. soudanense. A common outdated name that may still be reported by medical laboratories is Trichophyton mentagrophytes for T. interdigitale. The name T. mentagrophytes is now restricted to the agent of favus skin infection of the mouse; though this fungus may be transmitted from mice and their danders to humans, it generally infects skin and not nails.
Fungi that are already present in or on your body can cause nail infections. If you have come in contact with someone else who has a fungal infection, it may have spread to you. According to the American Academy of Dermatology (AAD), fungal infections affect toenails more commonly than fingernails because your toes are usually confined to your shoes, where they’re in a warm, moist environment.
Use soap and water to wash your feet, and dry well, including between toes. Trim your toenails -- straight across -- to keep them shorter than the end of your toe. Make sure the tools you use are clean, too. Wash clippers and files with soap and water, then wipe with rubbing alcohol. You might be tempted to cover up discolored nails with polish, but don't. Your nail bed can't "breathe," which keeps fungus from going away.
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