Why is Toe Nail Fungus So Hard to Treat?

Nail fungus is an unsightly, sometimes painful condition that afflicts millions of Americans. More common in the toe nails than the finger nails, this condition is notoriously difficult to treat. The following article discusses the reason why this is the case, and what physicians use most commonly to eradicate the infection.

Fungus is an organism, much like bacteria, viruses, parasites, plants, or animals. There are numerous species and forms of fungus, some large (like mushrooms), and some microscopic in size. The microscopic species of fungus are the ones that can invade the human body and use it as a scaffold to live off of. Infection of fungus can be seen in the lungs, the skin, and numerous orifices (such as the mouth and genital regions). While usually not life-threatening in reasonably healthy people, fungal infections are an annoyance and can cause numerous problems that prompt people to seek quick relief. Perhaps the most common location of fungal infection is found on the skin, which also includes the nails. Skin fungal infection goes by many common names depending on its location, including ‘ringworm’, ‘jock itch’, and ‘athlete’s foot’. Skin fungus thrives on the body where the environment is warm and moist, and that is why the feet and genital area seem to develop infections more readily. Foot fungus is transmitted, or ‘caught’, in wet areas like showers, locker rooms, and other public places where one is barefoot. Several different species of fungus can invade the feet, including molds and yeasts. However, the most common species of fungus that invades the foot is something called a dermatophyte. It is this species that causes nail infection most often.

Nails become infected when skin fungus takes advantage of a small crack or break in the nail tissue, and invades the skin surface resting underneath the nail. The fungus uses the nail above as a scaffold for living, and thrives on the material of the skin underneath. Eventually, it will cause the nail to become loosened, discolored, thickened, and misshapen as the skin and nail surface become partially destroyed by the infection. The infection creates nail debris that is seen externally as crumbly material exiting the end of the nail.

So, why is this infection difficult to treat? Athlete’s foot infection is easy to treat with topical creams, and the nail fungus is the same organism. Why would it be harder to treat when it is in the nail? The answer lies in the nature of the nail itself. Nails are hard, compressed plates of tissue composed of keratin. This material is generally impervious to water, and the penetration capabilities of medicines applied topically to the nail is generally poor without a special formulation. Even if the medicine could penetrate the nail, because the nail is more dense than skin the end concentration of medication reaching the undersurface of the nail is likely to be quite low, making it much less effective. Since the fungus lives off the skin underneath the nail, the medicine must reach the skin with enough concentration to kill it off in an environment that is most favorable to it- it’s home field so to speak. Most all topical anti-fungal medicines do not have this capability, as there is either poor penetration of the medicine due to their cream or solution-based formula, or the active ingredient is not active or concentrated enough against the more entrenched nail fungus. Many homespun therapies have developed in response to this difficult-to-treat nature. These include tea tree oil, Vicks, Listerine, vinegar soaks, as well as numerous others. Unfortunately, none of these have true demonstratable antifungal properties, and have not been demonstrated scientifically to kill nail fungus. Some of these treatments can flush away debris or clear superficial discoloration, leading many to falsely believe their fungus is cured when the change is only superficial and the fungus persists. Additionally, not all nail discoloration is due to fungus, and these superficial treatments can sometimes clear the nail discoloration, leading to the anecdotal rumor that they work on ‘fungus’.

Medical treatment of nail fungus is possible, but more involved than treatment of other basic non-life threatening skin infections. Clearly, the most effective way to deliver medicine into the skin underneath the nail is to bypass the nail altogether and send the medicine through the blood stream to enter the skin surface from underneath. This is accomplished by taking a pill, which dissolves in the stomach and enters the blood stream. There are two medicines currently available for this purpose, with one being used more commonly due to the medicine interaction issues of the other. Treatment must continue for three months before the infection can be effectively eradicated, and an additional six to nine months must go by before the destroyed nail grows out far enough that the new non-infected nail composes the entire nail length. Unfortunately, this medicine in rare cases can cause liver damage, and should be avoided in those with liver disease, those who are taking certain medications that break down in the liver similarly, or those with other health issues like kidney disease.

A new generation of topical medication has emerged to address the need to replace the internal medication, especially for those who cannot take it. These topical solutions use special oil-based formulations to help send the medicine through the nail plate. A prescription version has been available for quite some time, and a few over-the-counter versions have been developed that are distributed by physicians, primarily podiatrists. The most popular of these brands is called Formula 3. In the opinion of this author, this medication seems to be more effective clinically than the prescription topical medication based on eight years of generally unsuccessful use, and Formula 3 is used in his practice for this reason. All together, these topical medications are far less effective than the internal medicine, but are far safer for use. An extended period of use is required to destroy the fungus, which can take six months to a year depending on the rate of nail growth and severity of infection. Once again, much of this has to do with the ability of the medicine to reach the skin underneath the nail. These topical medications work better than store-bought creams and water-based solutions, which essentially only control fungus on the skin folds surrounding the nail. They do not work as well as internal medication, which still is not one hundred percent effective and still requires three months of treatment. All of this is due to the hardy nature of nail fungus given it’s entrenchment in the skin underneath the nail, and the relative shelter the thick nail plate provides.

Perhaps one day the pharmaceutical industry will develop a more effective medication for use with nail fungus. Unfortunately, in addition to the difficulty that current medication has in killing the fungus causing toe nail infection, the observational theory that some nails may simply be more apt to developing nail fungus infection over others and the general overwhelming presence of fungus in our environment leads to the possibility that toe nail fungus infection can reoccur over and over again. Steps can be made to prevent this infection from taking root in the nail again, but this requires regular vigilance.

Alternate technologies are being developed to make nail fungus treatment easier, and safer for repeated use if necessary. Laser therapy is becoming popular in many parts of the country. Several factors need to be considered by those seeking this treatment. It is expensive and insurance does not yet cover it. The results of a recent study in a medical journal did seem promising regarding it’s effectiveness. However, in this author’s opinion, the study (which was funded by the laser’s manufacturer) did have some flaws. It did not follow the patients long enough to determine if there was a true long-term ‘cure’, and did not have a large enough number of patients studied to convince him of its overall validity. More study is needed before this treatment should be considered the go-to treatment for nail fungus, especially given its cost. Until then, toe nail fungus remains a difficult to treat infection that affects millions world-wide, and demands a different approach than similar infections in the skin.