Fungal Nail Infection

Nail fungus 

Nail fungus, also known as onychomycosis, is a common condition in which there is fungal infection of the nail. There are four different types of onychomycosis. The most common type is called distal lateral subungual onychomycosis (DLSO) in which there is yellow discoloration, separation of the nail from the nail underlying skin, and debris collecting under the nail. In order to establish the diagnosis, I will perform a clipping from the toenail which is usually painless. We send the specimen to the lab for analysis. If the results are positive for onychomycosis, I will generally prescribe oral antifungal medication. However, if there is only one nail involved, I may consider a trial of topical therapy. The reason I do not use topical therapy as much as oral therapy is due to the lack of effectiveness of topical therapy. In DLSO, the fungus resides underneath the nail, which is why there is debris underneath the nail. The debris is being generated from the fungal infection. Topical therapies do not penetrate the nail very well and therefore, the effectiveness is less than 25%. With oral therapy, we can achieve successful treatment in over 75% of patients.

Before beginning oral treatment, we screen the patients for a history of allergies, previous history of liver problems, or hepatitis. Screening labs are also recommended. I generally start with oral terbinafine for a period of about 90 days. Follow up laboratory tests are also recommended mid-way into therapy.

Although many patients are hesitant to start an oral medication for the treatment of their nails, most patients have an excellent response to treatment with no harmful side effects. The most common question I get in regards to onychomycosis treatment is, “Won’t that harm my liver?” The short answer is no, although it is technically possible to suffer liver damage as a result of oral treatment, the chance of any hepatotoxicity is exceedingly rare.

Another important point to note is that although treatment is generally successful with oral antifungal medication, the full result will not be seen until about 1-2 years after the treatment. Why? It takes 1-2 years to grow a completely new toenail. However, as the new nail is growing in, you will see the old nail going away so during this period, there is a gradual and noticeable improvement.

I always encourage my patients to treat their toenail fungal infections as long as they are healthy enough to do so. One of the main reasons that I do is that fungal nail infections can often lead to other fungal skin infections such as athlete’s foot and jock itch. In addition, it is possible to give your fungal infection to another member in the household. So, by treating your fungal nail infection, you could be preventing the spread to other individuals. Another reason I encourage treatment of onychomycosis is that it can be a cause for more concerning infections in patients who have other health problems such as diabetes, obesity, and poor cardiovascular health. Having healthy feet can save your life!


Justine Park, MD Dr. Park is a Board-Certified Dermatologist who has been practicing at Glendale Dermatology since 2007.

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