Treatment for a Fungus Under the Toenail


Fungi are organisms that thrive in moist dark environments. Fungal infection of toenails (also known as onychomycosis or tinea unguium) is most commonly caused by Trichophyton rubrum, a dermatophyte. There are several available treatment options for curing fungal nail infections.


According to a 1997 study from the Archives of Dermatology, onychomycosis is prevalent in 2 to 3 percent of the U.S. population. Toenails are affected in up to 90 percent of cases. It occurs twice as often in men than women and increases with age. Toenail fungal infection is not only a cosmetic problem, but also may cause pain with activities of daily living, like walking. Embarrassment about unsightly toenails lowers self-confidence and self-esteem. Individuals with toenail onychomycosis may experience social aversion when going to the beach. People who have had past episodes of onychomycosis are likely to have recurrent infections.


Three tests can diagnose a fungal nail infection: KOH test, fungal culture and dermatophyte test medium (DTM) culture. The KOH test is a microscopic exam that shows the fungus. Fungal cultures are not routinely done, except in clinical trials, because they take three to four weeks for the results and are expensive. DTM culture selectively isolates dermatophytes; it is less expensive than a fungal culture, it can be done in a doctor’s office and results are available in three to seven days.


Toe fungal infection is acquired by minor trauma to the nail bed where the nail meets the skin. Infection begins at the tip and extends down, spreading across the entire nail. Typically, it causes yellowish or brownish nail discoloration, debris accumulation under the nail and detachment of the nail plate from the nail bed. As a result, nails thicken, break easily and crumble. Toenails are infected by fungus more often than fingernails. Both nails may be infected in some patients.


Standard treatment consists of oral antifungal agents. According to the Mayo Clinic, the most effective oral agents are itraconazole or terbinafine; fluconazole is less effective and not FDA approved. The duration of therapy is 12 to 24 weeks for toenail fungus. According to the Doctor Fungus website, itraconazole is given for one week each month, followed by nothing for the remainder of the month. This cycle is repeated three to four times for toenails. It is harder to treat toenails than fingernails, because toenails grow slower.

Topical medicines may also be used to treat fungal nail infections. Penlac nail lacquer is FDA approved; it is applied to the nail and surrounding skin once a day for one week, then removed with alcohol and the cycle is repeated. Topical medications are not as effective as oral medicines in curing fungal nail infections. With Penlac, toenails may clear within 12 months, or longer.

Side Effects

According to the Lamisil package insert, there have been rare cases of liver failure, some leading to death or liver transplant, with these medications. There have also been isolated reports of serious skin reactions. Consequently, Lamisil is not recommended for patients with chronic or active liver disease, while Sporanox is not recommended for patients with congestive heart failure. Ask your doctor if you are a candidate to take these medications.

About this Author

Based in New Jersey, John Riefler III has been writing since 1987. His articles have appeared in “MD Magazine,” “Emergency Medicine” and “Hospital Practice.” Riefler holds a Bachelor of Science in biology from Bucknell University, a Master of Science in microbiology from M.U.S.C. and an M.D. from St. George’s U. School of Medicine.