Harvard Health Letter

By the way, doctor: Cut off from toenail fungus medicine too soon?

Q. Penlac didn't work to cure my toenail fungus. I took an oral medication, terbinafine, and saw some improvement, but my insurance company won't approve more than a few months of treatment. It's frustrating to finally have a solution and then be cut off.

A. I am not surprised that ciclopirox (Penlac) didn't work. It's painted on like nail polish, so it's nice and easy to use. But toenails are made of a tough, impenetrable protein called keratin, so the medicine doesn't reach fungi growing inside them very well. Penlac is effective less than 10% of the time.

There are several oral antifungal medications. Terbinafine (the active ingredient in Lamisil but also available as a generic) is the best of the bunch. A three-month course clears the fungal infection about 60% to 70% of the time. Itraconazole (Sporanox) is an alternative, but studies have shown it to be a little less effective, and there are more problems with drug interactions with itraconazole than with terbinafine.

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