Fungal nail infections and the resultant nail destruction can promote other sources of infection like cellulitis (a bacterial skin infection) and other forms of tinea, and aggravate foot problems resulting from other illnesses such as diabetes. Diagnosis is usually confirmed by looking at nail clippings through a microscope or other tests before starting treatment.
In some cases of suspected nail fungus there is actually no fungal infection, but only nail deformity. A 2003 source gives a figure of 50% whereas a more recent source claims that fungus is present in 65 to 95 percent of cases. Avoiding use of oral antifungal therapy (e.g. terbinafine) in persons without a confirmed infection is a particular concern because of the possible side effects of that treatment. However, according to a 2015 study, the cost in the United States of testing with the periodic acid–Schiff stain (PAS) was about $148. Even if the cheaper KOH test is used first and the PAS test is used only if the KOH test is negative, there is a good chance that the PAS will be done (because of either a true or a false negative with the KOH test). But the terbinafine treatment only cost $10 (plus an additional $43 for liver function tests). In conclusion the authors say that terbinafine has a relatively benign adverse effect profile, with liver damage very rare, so it makes more sense cost-wise for the dermatologist to prescribe the treatment without doing the PAS test. (Another option would be to prescribe the treatment only if the potassium hydroxide test is positive, but it gives a false negative in about 20% of cases of fungal infection.) On the other hand, as of 2015 the price of topical (non-oral) treatment with efinaconazole was $2307 per nail, so testing is recommended before prescribing it.
Oral/combination therapy. Some studies have shown that taking antifungal pills and applying antifungals to your nails can be more effective than using either treatment alone. Oral medications can typically treat toenail fungus in three months. In stubborn cases, topical and oral medications may be combined to provide the best possible treatment. Oral medications must be prescribed by your physician or health care practitioner.
Toenail fungus, also called onychomycosis, is a common fungal infection of your toenail. The most noticeable symptom is a white, brown, or yellow discoloration of one or more of your toenails. It may spread and cause the nails to thicken or crack. Sandal season or not, toenail fungus typically isn’t what you want to see when you look at your feet. Luckily there are many treatments you can try.
Dr. Kyoung Min Han is a podiatrist (foot and ankle specialist) practicing in Southern California. Dr. Han completed her undergraduate education at the University of California, San Diego, and went on to the New York College of Podiatric Medicine to pursue her medical training. She returned to her native Southern California to complete a three-year foot and ankle surgical residency, followed by subspecialty training in a sports medicine fellowship.
Toenail fungus is an infection that gets in through cracks in your nail or cuts in your skin. It can make your toenail change color or get thicker. It can also hurt. Because toes are often warm and damp, fungus grows well there. Different kinds of fungi and sometimes yeast affect different parts of the nail. Left untreated, an infection could spread to other toenails, skin, or even your fingernails.