Onychomycosis (nail fungus) is a common infection of the toenails most often caused by the fungus Trichophyton rubrum. The infection causes discoloration, thickening, separation of the nail from the nail plate, and accumulation of debris under the nails.
The cause of nail infection is thought to be fungus from neighboring skin that migrates into the nail.
Onychomycosis is generally a benign condition, but it can sometimes cause mild discomfort when the shoe presses on a very thickened nail. Most people inquire about fungal infection because they don’t like the appearance of their toenails.
Oral antifungal treatment is often successful in eradicating the fungus, but there is no guarantee of restoring the nail to a normal appearance. Factors which decrease the chance of clearing the nail include older age, immune deficiency, malnutrition, poor hygiene, and significant accumulation of debris beneath the nail.
Pharmacotherapy:
Topical treatments are much less effective than oral treatment, and I don’t usually Rx them.
The oral medication I use most often is terbinafine 250 mg, taken once daily for 90 days. I have never seen any evidence of toxicity in my patients who have used toxicity in over 20 years. However, to be safe, I order a liver panel to be done one month after starting terbinafine.
Nails grow very slowly. It will take several months for the nails to clear and look normal. Many times, when patients see that the nails are starting to clear, I am asked to prescribe a refill of terbinafine. Either the nail will clear, or it will not, but 90 days is sufficient to eradicate the fungus.
Even if your toenails return to a normal appearance, there is a high chance of a recurrence. Fungus grows well in warm, moist, dark places, such as during the day while you are wearing socks and shoes, which trap moisture. You must be diligent with foot hygiene! During your morning shower, apply liquid soap to the feet. Using a soft toenail brush or nylon shower puff, gently scrub the feet and area around the nails. In the evening and/or after a workout, take your socks off and scrub the feet again.
In general, it takes 2 days for a shoe to dry fully. At the end of the day, I place my shoes outside in the sun; the UV light is fungicidal, and the sun dries the shoe faster. For my sneakers, sometimes I remove the liners and gently scrub them in the sink, followed by placing them in the sun.