Toenail Fungus 2026: Causes, Treatment & When to See a DPM

If your toenails have turned yellow, brown, or white — and they’re thickening, crumbling, or separating from the nail bed — you’re likely dealing with nail fungus. In our clinic at Balance Foot & Ankle, toenail fungus is one of the most common conditions we treat, and it’s also one of the most commonly misidentified. Many patients come in thinking they have nail fungus when it’s actually nail trauma, psoriasis, or another condition.

What Is Nail Fungus?

Nail fungus, medically known as onychomycosis, is an infection caused by dermatophytes, yeasts, or molds that invade the nail plate, nail bed, or surrounding tissue. The toenails are far more commonly affected than fingernails, largely because the feet create a warm, moist, dark environment that fungi thrive in.

Nail fungus accounts for about 50% of all nail disorders seen in medical practice, according to a 2024 review in the Journal of Clinical and Aesthetic Dermatology. It affects an estimated 10% of the global population — and rates are higher in older adults, diabetics, and people with weakened immune systems.

In our Howell and Bloomfield Hills clinics, we confirm nail fungus with a nail culture or KOH test (potassium hydroxide), not just a visual exam. This matters because the treatments for fungal infection differ significantly from treatments for other nail conditions.

https://www.youtube.com/watch?v=Yt7H5AYf8lA

What Does Nail Fungus Look Like?

Nail fungus doesn’t always look the same — the appearance varies depending on the type of fungus, how long it’s been present, and which part of the nail is affected. Here’s what to watch for:

• Yellow, brown, or white discoloration — often starts at the tip or edge of the nail
• Thickened nails — the nail becomes difficult to trim or grows unevenly
• Brittle, crumbly, or ragged edges — nail breaks or chips easily
• Distorted shape — nail may curl or grow in an unusual direction
• Nail separation (onycholysis) — nail lifts away from the nail bed
• Debris under the nail — white, yellow, or brown buildup beneath the nail plate
• Odor — in more advanced infections, a mild foul smell may be present

One nail may be affected initially, but without treatment, fungus spreads easily to neighboring nails, skin (causing athlete’s foot), and potentially to other people sharing your household.

Types of Nail Fungus

There are several distinct clinical patterns of nail fungus, each caused by slightly different organisms and affecting different nail structures:

• Distal subungual onychomycosis (DSO) — the most common type; starts at the tip/underside of the nail and spreads toward the cuticle; caused mainly by Trichophyton rubrum
• White superficial onychomycosis (WSO) — white chalky patches on the top surface of the nail; caused by T. mentagrophytes or Fusarium
• Proximal subungual onychomycosis (PSO) — begins near the cuticle; associated with HIV and immune suppression
• Candidal onychomycosis — caused by Candida yeast; more common in fingernails and in people with diabetes or weakened immunity
• Total dystrophic onychomycosis — advanced infection destroying the entire nail

What Causes Nail Fungus?

The organisms responsible for nail fungus enter the nail through small cuts, breaks, or the gap between the nail and nail bed. Certain conditions dramatically increase your risk:

• Walking barefoot in shared wet areas (pools, locker rooms, public showers)
• Sweaty or poorly ventilated feet
• Wearing tight shoes that crowd the toes
• A history of athlete’s foot
• Diabetes, poor circulation, or compromised immunity
• Advancing age (nails grow more slowly and thicken with age)
• Nail trauma (stubbing toes, ill-fitting footwear)
• Family history of fungal infections

In our practice, we frequently see nail fungus develop after patients stop wearing sandals at the gym, share nail clippers, or experience a period of immune stress — such as after surgery, illness, or antibiotic use.

Nail Fungus Treatment Options

Nail fungus is notoriously difficult to eliminate because the infection lives inside the nail structure — topical treatments have trouble penetrating. The best treatment depends on how severe the infection is, how many nails are affected, and your overall health.

Oral Antifungal Medications

Oral terbinafine (Lamisil) is currently the most effective treatment for nail fungus, with cure rates around 70–80% after a 12-week course. It works by circulating through the bloodstream to reach the nail bed. Itraconazole is an alternative, especially for candidal infections. Liver function monitoring is recommended during treatment.

Topical Antifungal Treatments

Prescription topical antifungals like efinaconazole (Jublia) and tavaborole (Kerydin) are applied daily for up to 48 weeks. They’re best for mild-to-moderate cases or for patients who can’t take oral medications. Over-the-counter products (clotrimazole, tolnaftate) are minimally effective against established nail infections.

Laser Therapy

Laser treatment uses focused light energy to destroy fungal cells within the nail without harming surrounding tissue. In our clinics, we offer laser therapy as a safe, medication-free option. Multiple sessions are typically needed. While laser therapy doesn’t require blood monitoring, it’s generally not covered by insurance.

Nail Debridement

Periodic nail debridement — trimming and thinning the infected nail — doesn’t cure fungus but reduces the fungal load, makes topical treatments more effective, and relieves pressure and pain. We perform this in-office as part of a comprehensive treatment plan.

At-home foot soaks with diluted antifungal solutions (undecylenic acid-based products like Funginix or Formula 3) may help as adjuncts, but should not replace medical treatment for moderate-to-severe infections.

How to Prevent Nail Fungus

• Keep feet clean and dry — change socks if your feet sweat heavily
• Wear moisture-wicking socks and breathable shoes
• Use antifungal powder or spray on feet and in shoes
• Wear sandals or flip-flops in public locker rooms, showers, and pools
• Trim nails straight across; don’t cut too short
• Don’t share nail clippers, files, or towels
• Disinfect nail clippers and pedicure tools before use
• Choose nail salons that properly sterilize their equipment

Frequently Asked Questions

Can nail fungus go away on its own?

Rarely. Without treatment, nail fungus almost always worsens over time — spreading to more nails and deepening within the existing infection. Natural remedies like tea tree oil may slow growth in very mild cases, but aren’t reliable cures. Most cases require either prescription topical or oral treatment.

Is nail fungus contagious?

Yes — nail fungus is contagious. It can spread person-to-person in shared spaces (pools, locker rooms), through shared nail tools, and from one nail to another on the same person. People with athlete’s foot (tinea pedis) commonly develop nail fungus because the same organism spreads from the skin to the nail.

How long does nail fungus treatment take?

Treatment duration depends on the method: oral terbinafine is typically taken for 12 weeks, while topical prescription medications may be applied for 36–48 weeks. After treatment clears the infection, it takes an additional 6–12 months for the nail to grow out fully clear and healthy.

Does bleach kill toenail fungus?

Bleach is not recommended for treating nail fungus. While diluted bleach has antifungal properties, it can cause chemical burns on skin and nails and doesn’t penetrate deeply enough to reach the fungus within the nail plate. Prescription treatments are far safer and more effective.

What happens if nail fungus is left untreated?

Untreated nail fungus continues to thicken and spread. It can cause pain with footwear, difficulty walking, and can spread to other nails and skin (athlete’s foot). In people with diabetes or neuropathy, it increases the risk of secondary bacterial infections and foot ulcers.

Sources

• Gupta AK, et al. Onychomycosis: A Review. J Eur Acad Dermatol Venereol. 2024.
• Lipner SR, Scher RK. Onychomycosis: Treatment and Prevention of Recurrence. J Am Acad Dermatol. 2019;80(4):853–867.
• American Podiatric Medical Association. Nail Fungus. apma.org. 2025.
• Kreijkamp-Kaspers S, et al. Oral antifungal medication for toenail onychomycosis. Cochrane Database Syst Rev. 2017.

When Shoes Aren’t Enough — Dr. Tom’s Top 9 Orthotics

About 30% of patients I see for foot pain need MORE than a great shoe — they need a structured insole. Below: my complete 2026 orthotic ranking with pros, cons, and the specific patient I’d give each one to.