Fungal Nail Infections

What Is a Fungal Nail Infection?

Onychomycosis is a fungal infection of the nail, caused by dermatophytes, yeasts, or molds that invade the nail plate and the skin beneath it. It is one of the most common nail disorders, accounting for about half of all nail problems seen by podiatrists. Toenails are far more frequently affected than fingernails, due to the warm, moist environment inside shoes.

Fungal nail infections are often mistaken for simple discoloration or nail damage. An accurate diagnosis from a podiatrist ensures you receive the right treatment rather than wasting time on ineffective home remedies.

Causes and Risk Factors

• Exposure to damp public spaces — locker rooms, swimming pool areas, and communal showers are common sources of fungal organisms
• Athlete's foot spreading to the nails — the same fungus that causes tinea pedis can migrate to infect the nail
• Minor nail or skin injuries — even a small crack in the nail or surrounding skin provides an entry point for fungus
• Tight footwear — creates the warm, moist conditions where fungus thrives
• Age — nails become slower-growing and more brittle with age, making them more susceptible
• Circulation problems — reduced blood flow to the feet slows the body's immune response to infection
• Diabetes — compromised immunity and circulation significantly increase risk

Symptoms

• Nail that appears yellow, brown, white, or green
• Thickened or distorted nail shape
• Brittle, crumbly, or ragged nail edges
• Nail that separates from the nail bed (onycholysis)
• A slight foul odor from the infected nail
• Debris accumulating beneath the nail

Diagnosis

Dr. Ross will examine the affected nail and may take a small nail clipping or scraping to send to a laboratory for culture. This confirms the presence of fungus and identifies the specific organism, which guides treatment selection.

Treatment

Topical Antifungal Medications

Prescription-strength topical lacquers and solutions are applied directly to the nail and surrounding skin. These are most effective for mild to moderate infections where the nail root is not yet involved. Treatment typically continues for 6–12 months as the nail grows out.

Oral Antifungal Medications

For moderate to severe infections, oral antifungal medications (such as terbinafine or itraconazole) are significantly more effective than topical treatments alone. They travel through the bloodstream to the nail root, where new healthy nail grows. A course of treatment typically lasts 3–4 months, with the full result visible once the nail has fully grown out (6–12 months).

Nail Debridement

Regular professional trimming and thinning of the infected nail improves the penetration of topical medications and reduces discomfort.

Nail Removal

In severe or long-standing cases, surgical or chemical removal of the nail allows topical antifungal treatment to reach the nail bed directly and gives a new, healthy nail the best chance to grow in cleanly.