Fungus of Toenails

Onychomycosis (Toenail Fungus)

Fungus is another term for the simple plants called molds. Molds grow, for example, not only on bread and cheese, but also on the skin and toenails. “Athlete’s foot” is caused by molds growing on the skin of the foot. The same molds may invade the keratin (protein) of the nails and cause a thick, crumbly nail. The medical term for fungus infection of a nail is onychomycosis. The large toenails are most commonly infected but other toenails are frequently affected. Onychomycosis of the toenails is a cosmetic nuisance. Ladies who wear open-toed footwear are displeased to have crumbly, unsightly toenails. Nail polish is effective in disguising mild onychomycosis but fails to camouflage severe onychomycosis. Sometimes, onychomycosis causes massive thickening of the nail, and this may cause discomfort from pressure against the shoe.  Sometimes because we wear shoes that chronically rub or press on certain nails, some of the toenails will become thick and crumbly and resemble onychomycosis when fungus is not the cause at all!


Unfortunately, medicines applied to the toenail will not cure your toenails. While ointments, solutions, and powders will control fungus infections of the skin (athlete’s foot), they are not effective when the fungus invades the nail. The nail acts as “armor,” protecting the fungus from medicines applied to the nail.

Treatment, for 3 to 4 months, with antifungal antibiotics taken by mouth, clears onychomycosis in about one half of patients. These internal antifungal medicines are expensive. Rarely they may cause serious side effects. Unfortunately, in about one half of patients, these medications fail and the nail remains infected. At best, these medications only clear the infection; they do not provide a permanent cure. The fungus infection persists on the skin of the foot, and with time, may again invade the nail. About one out of four “cured” persons will have a recurrence of toenail onychomycosis within 3 years.


The nuisance of toenail fungus can be minimized by carefully scraping or cutting away all of the diseased nail. A large toenail clipper combined with scraping using a corn file works best, since ordinary nail files or emery boards are inadequate. Soaking feet for 10 minutes in lukewarm water softens nails and makes it easier to cut and trim your nails.  Do not use clippers on nails not diseased.  The clippers should be cleaned with bleach and dried well between use.


Fungus infection of the toenails is a common and stubborn nuisance that can be partially controlled by periodic removal of the diseased nail. Certain newer antifungal medicines taken by mouth will clear about one half of toenail infections, but these medicines are expensive and may cause side effects.