Almost 30 million Americans—approximately 13% of the population—has a fungal infection of the nails (also known onychomycosis).
Why are fungal infections so difficult to treat successfully?
Dr. Abuabara: Nails grow very slowly, and the medicines available to treat fungal infections primarily arrest the growth of the fungi. Thus, you have to wait for the affected nail to grow out to get rid of the infection. This can take three to six months for the fingernails and up to a year for the toenails.
Dr. Elewski: They're not as hard to treat as they used to be. In the past, the available oral treatments had to be taken every day until the nail completely grew out, and they had low cure rates. The newest oral drugs don't have to be taken as long and they cure 80% of infections. The remaining 20% of infected nails might require a longer course of oral medication or a combination of oral and topical treatments, but 100% of infections can be cured today.
What happens if onychomycosis is left untreated?
Dr. Elewski: It will continue to worsen. It may start on one nail, then spread to a second nail, then to a third, fourth, and fifth. Then it might move to the other foot or to the fingernails. Studies show that about half of people with onychomycosis on their toenails experience pain as the nails thicken.
Dr. Lynde: For the most part onychomycosis is a cosmetic nuisance, but it can spread and you can get secondary infections. Untreated, it can permanently damage affected nails.
Briefly discuss the treatments currently available, along with their advantages and disadvantages.
Dr. Elewski: The medications used to treat onychomycosis are safe and effective. They've been on the market for a long time, and well over 100 million people worldwide have taken them. Some of them are not good for certain people. You should discuss the best choice for your particular needs with your doctor.
Griseofulvin is one of the older drugs used to treat onychomycosis. It's a safe drug that's a standard treatment for fungal infections on the scalp, but its cure rate for onychomycosis is less than 20%.
Today, we have Lamisil and Sporanox as highly effective treatments of onychomycosis. Lamisil is taken just once a day, with or without food, for three months (six weeks for onychomycosis of the fingernails). Sporanox should be taken with food and has some significant drug interactions, but it also is a safe, effective treatment when used correctly.
Diflucan is another oral treatment. The FDA has not approved Diflucan for the treatment of onychomycosis, but it has been approved for that use in other countries and is very safe to use. I find it particularly effective in treating yeast infections of the nails.
With most of these medications you have to monitor the patient's liver function, but that's not necessarily a reason to fear them. Tylenol, in too high of a dosage, also can cause liver damage.
Explain how Penlac works, and whom it's best suited for.
Dr. Elewski: A topical treatment, Penlac applies like a nail lacquer. You apply a fresh coat daily, then once a week remove all seven layers of polish with rubbing alcohol and trim your nails. Repeat the daily and weekly routines for as long as your doctor recommends.
Penlac is not as effective as the oral treatments—its cure rate is less than 12%. However, it's an appropriate choice when you can't or don't want to use an oral treatment, such as with children with fungus. It's also appropriate to use for people with a mild infection, in conjunction with an oral drug, or as a preventive.
Are there other, new antifungal treatments in the works?
Dr. Elewski: There are other topical lacquers we're studying here at University of Alabama, Birmingham, and Schering Plough has a topical gel it's looking at. I think treatments like these will have better cure rates than the ones currently available, but they all are at least a year or two from coming to market. Nor do I think they'll be as effective as the newer oral treatments such as Lamisil.
Some people swear by over-the-counter treatments such as Fung-Off and home remedies like diluted bleach or vinegar. Are there certain types of onychomycosis they do work on?
Dr. Gold: There are a variety of over-the-counter treatments and home remedies that have been around for years. Most dermatologists believe these agents provide little relief from nail diseases, and that prescription medicines offer the best hope for effective treatment at this time.
Dr. Abuabara: They occasionally can be effective, particularly if the infection is mild (which means less than 25% of the nail is affected) and is primarily on the central aspect of the nail. The individual has to use the medicine consistently until the infection completely grows out, which takes several months.
What are some of the conditions onychomycosis is confused with, and what are the dangers in labeling something a fungal infection without a definitive diagnosis?
Dr. Daniel: Psoriasis, dishydrotic eczema, and contact dermatitis are the conditions most commonly confused with onychomycosis. Another is a thickened nail caused by trauma to the nails from shoes that are too narrow or too short.
Although rare, some forms of skin cancer can show up as a tumor under the nail. If mislabeled as a fungal infection of the nail, time wasted treating the condition could allow the cancer to spread. The Food and Drug Administration (FDA) recently issued a mandate urging physicians to confirm their diagnosis through a lab test before prescribing an oral antifungal.
Is there any connection between fungal infections of the skin and nails?
Dr. Abuabara: Most individuals tend to have chronic infections of the skin that subsequently infect the nails. Less commonly, a blunt trauma loosens the nail plate and allows fungi entry to the nail bed. It appears from research that the most important factor in getting a fungal infection is an individual's susceptibility to the fungi coupled with the capability of her immune system to fight it off.
Are some people more susceptible to onychomycosis than others?
Dr. Daniel: Without a doubt. We think it's one of two things that makes certain people more susceptible: It's either a problem with the T-cell (a component of the blood that helps protect the body from infection) that prevents it from recognizing fungi as abnormal to the skin and nails, or there's something different about the keratin that makes up these people's nails.
How likely is someone to experience additional fungal infections of the nail, and how is that risk best minimized?
Dr. Daniel: For those who are genetically susceptible, the risk of reoccurrence is quite high because even after the original infection is cleared from their nails, the person is repeatedly exposed to fungi in her shoes, her shower, her carpet, etc.
To minimize your risks of onychomycosis returning, make sure no one else with whom you come in close contact has it. You also want to make sure you wear properly fitted shoes to minimize trauma to your toenails that could break the protective seal between the nail plate and nail bed. Always wear shoes or sandals in public places.
I also recommend to my susceptible patients that they continue to use a topical antifungal skin cream (such as Loprox) and Penlac as preventive measures.
How contagious is onychomycosis?
Dr. Gold: Fungi easily can be spread by nail technicians who use unsterile instruments, and they flourish when artificial nails are placed over an already infected natural nail.
Can artificial nails cause onychomycosis?
Dr. Scher: Yeast infections and pseudomonas bacterial infections are closely associated with artificial nails, but artificial nails don't cause fungal infections. If someone is wearing artificial nails and gets a fungal infection, there is a connection, but the artificial nail is not the direct cause.
The fungi kingdom is comprised of several fungi families, including yeasts, dermatophytes, and mpld. To understand fungal infections of the nails, also called onychomycosis, you need only be concerned with two broader classes of fungi -- yeasts and dermatophytes. These two classes of fungi differ only in the nutrients they need to survive.
Dermatophytes are a highly specialized group of fungi that break down keratin -- the protein the makes up hair and nails -- and absorb its nutrients. One dermatophyte in particular -- trichophyton rubrum -- reportedly is responsible for than 80% of onychomycosis (tinea unguium), 96% of athlete's foot infections (tinea pedis), 90% of jock itch infectios (tinea cruris), and more than 50% of ringworm infections of the body (tinea corporis).
In contrast, yeast, another specialized segment of fungi, thrive on sugar. Candida albicans, the most common yeast organism to infect humans, is found naturally no mucous membranes in the vagina, mouth, and gastrointestinal tracts. When the natural balance of yeast is upset, a yeast infection can result. Yeast infections also can develop under the proximal nail fold, under a nail plate that has separated from the nail bed, and between the nail plate and lifted artificial nail product.