Toenail fungus, medically known as onychomycosis, is a fungal infection of the nail that typically starts as a small discolored spot beneath the nail's surface and slowly spreads if left untreated. Mild cases sometimes respond to over-the-counter care, but moderate to severe infections generally need a podiatrist's help to fully clear and to keep from coming back.
It's one of the more stubborn conditions we treat, largely because the nail itself acts as a barrier that keeps topical medications from reaching the infection underneath. Below, we walk through how to recognize toenail fungus, why it happens, and the removal options — from at-home treatments to in-office procedures — that actually work.
What is toenail fungus?
Onychomycosis is caused by fungal organisms that infect the nail plate and the nail bed underneath it. It often begins as a small white or yellow spot near the tip of the nail that's easy to miss or dismiss in the early stages. Left alone, the infection tends to spread across the nail and can eventually involve the nail matrix, where the nail grows from.
Fungus thrives in warm, moist environments, which is why it's so common in toenails — shoes and socks create exactly the conditions it needs. It also spreads easily in places where people walk barefoot, like locker rooms, showers, and pool decks.
What are the symptoms of toenail fungus?
Toenail fungus usually develops gradually, and the appearance of the nail changes as the infection progresses. Common signs include:
- White, yellow, or brownish discoloration of the nail
- Thickened nails that are harder to trim
- Brittle, crumbly nails that break or split easily
- A distorted, misshapen, or gnarled nail appearance
- A mild foul odor from the affected nail
- Nail separating slightly from the nail bed in more advanced cases
Toenail fungus is often preceded by or occurs alongside athlete's foot or other skin infections on the foot, since the same types of fungi are usually responsible.
How is toenail fungus treated?
Treatment depends on how severe the infection is, how many nails are involved, and your overall health. We generally recommend a professional evaluation rather than relying solely on over-the-counter products, since an accurate diagnosis and the right combination of treatments meaningfully lowers the chance of recurrence.
Topical treatments
Medicated creams, lotions, and antifungal nail polishes are applied directly to the nail and surrounding skin. They work best for mild infections or ones caught early, and typically need to be used consistently for months while the nail grows out clear.
Oral antifungal medication
Oral antifungals work from the inside out and tend to clear infections more effectively than topical treatment alone, especially for thicker or more extensive fungal involvement. Because these medications may require an extended course and can interact with other medications, we monitor patients throughout treatment.
Laser treatment
FDA-cleared laser therapy targets the fungus with concentrated light energy that heats and damages the fungal cells without harming the surrounding tissue. Most patients need more than one session, with the number depending on how severe the infection is. Laser treatment is often combined with topical or oral medication for the best results.
Nail debridement
Thinning or trimming the thickened, infected portion of the nail in-office reduces the fungal burden and helps topical medications penetrate more effectively. This is often paired with one of the treatments above rather than used alone.
Why treating toenail fungus takes patience
One of the most important things to understand about toenail fungus is that clearing the infection and growing a fully normal-looking nail are two different milestones. Toenails grow slowly, so even after the fungus itself is eliminated, it can take many months for a healthy, clear nail to fully grow out and replace the damaged one. Consistency with your treatment plan during that window matters — stopping early is one of the most common reasons fungus comes back.
Good foot hygiene alongside treatment also helps prevent recurrence: keeping feet dry, changing socks regularly, disinfecting shoes, and treating any athlete's foot promptly so it doesn't reinfect the nail.
When should you see a podiatrist?
See a podiatrist if a nail has been discolored or thickened for more than a few weeks, if over-the-counter treatments haven't helped, or if the infection is spreading to other nails. Seek care sooner if you have diabetes, poor circulation, or a weakened immune system, since foot infections in these situations can progress more quickly and deserve prompt attention. When you're ready, you can request an appointment at either of our Northern Utah offices.
Medically reviewed by the physicians at Wasatch Foot & Ankle Institute. Our board-certified, fellowship-trained podiatrists provide foot and ankle care in Farmington and South Ogden, Utah. This article is for general education and is not a substitute for an in-person evaluation.