Toenail Fungus (Onychomycosis)

Onychomycosis is a fungal infection of the toenail affecting an estimated 10% of the general population — and up to 50% of adults over age 70. The infection begins under the nail plate and progressively destroys nail tissue. The most common culprits are dermatophyte fungi (Trichophyton rubrum in particular), though yeast and non-dermatophyte molds are also responsible.

Signs include thickened, brittle, or crumbly nails; yellowing, brown, or white discoloration; nails that separate from the nail bed (onycholysis); and a faint odor. The condition rarely resolves on its own and can spread to other toenails and to family members through shared surfaces.

  • Topical antifungals (ciclopirox, efinaconazole) work for mild, superficial infections but penetrate the nail plate poorly in thicker infections
  • Oral antifungals (terbinafine, itraconazole) are significantly more effective but require lab monitoring; treatment typically runs 12 weeks
  • Laser therapy is an emerging option with growing evidence for moderate cases
  • Cure rates take 12–18 months to fully assess because nails grow slowly; a clear nail at the base after treatment is a positive sign
  • Prevention: keep feet dry, change socks daily, wear shower shoes in communal areas, trim nails straight across

Ingrown Toenails

An ingrown toenail occurs when the nail edge grows into the surrounding skin, causing pain, redness, and swelling. When skin is breached, infection follows quickly — with warmth, drainage, and in severe cases, granulation tissue. The great toe is most commonly affected.

Common causes include improper nail trimming (cutting too short or rounding the corners), tight footwear, nail trauma, and genetic nail curvature. Mild cases can sometimes be managed at home with warm water soaks and careful lifting of the nail edge; however, once infection is present or the condition is recurrent, professional treatment is needed.

Podiatric treatment options include partial nail avulsion (removing the ingrown border under local anesthesia) or permanent matrixectomy using a chemical (phenol) to destroy the nail matrix and prevent regrowth of the offending border. Matrixectomy has a very high success rate for recurrent ingrown nails with minimal cosmetic impact.

Patients with diabetes should never attempt self-treatment of ingrown toenails. Even a small break in the skin can lead to a serious infection. See a podiatrist at the first sign of ingrown nail pain.

Plantar Warts

Plantar warts are caused by the human papillomavirus (HPV) infecting the outer layer of skin on the bottom of the foot. The virus thrives in warm, moist environments — locker rooms, pools, and shared showers are common transmission sites. Warts appear as rough, grainy lesions on the heel or ball of the foot, often with small black dots (thrombosed capillaries) visible at the center. Because they grow inward under pressure, they can cause significant pain with walking.

Warts may resolve on their own over months to years, but treatment accelerates resolution and prevents spread. Options include:

  • Salicylic acid: repeated application destroys the infected tissue layer by layer; effective for mild cases
  • Cryotherapy: liquid nitrogen freezes the wart; often requires multiple treatments
  • Cantharide (blister beetle extract): applied in-office, causes blistering that lifts the wart
  • Swift microwave therapy: newer treatment that activates the immune response with growing evidence for resistant warts
  • Surgical excision: reserved for large or resistant warts

Athlete's Foot (Tinea Pedis)

Athlete's foot is a superficial fungal infection of the skin, most commonly affecting the spaces between the toes (interdigital type) and the sole (moccasin-type). Symptoms include itching, burning, scaling, peeling, and in severe cases, blistering. Chronic moccasin-type athlete's foot produces a fine, powdery scale across the entire sole and heel and can be mistaken for dry skin.

The same dermatophytes that cause nail fungus are responsible. Athlete's foot can serve as a reservoir that seeds toenail infections. Treatment with topical antifungals (clotrimazole, terbinafine cream) is effective for most cases; oral antifungals are reserved for extensive or recurrent infection. Prevention mirrors that of nail fungus: keep feet dry, wear breathable footwear, and change socks frequently.

Corns and Calluses

Calluses are areas of thickened skin that develop in response to repeated friction or pressure — a normal protective response. They typically form on the ball of the foot, the heel, or under the big toe. Corns are a more focused variation: a central hard core (hard corn) or soft, macerated tissue between the toes (soft corn) that can be quite painful when pressed.

The underlying cause is almost always mechanical — ill-fitting footwear, abnormal gait, or bony prominences (hammertoes, bunions). Treating only the skin without addressing the structural cause leads to rapid recurrence.

  • Padding and accommodative orthotics redistribute pressure and provide immediate relief
  • Debridement (professional trimming) by a podiatrist is safe and effective — home cutting with razors or corn plasters is not recommended, especially for patients with diabetes or poor circulation
  • Definitive correction addresses the underlying deformity (e.g., hammertoe correction, bunionectomy)

Skin Cracks and Fissures

Heel fissures occur when dry, thickened skin at the heel rim cracks under body weight. Mild fissures are a cosmetic nuisance; deep fissures bleed, cause pain with walking, and create an entry point for bacterial infection. Risk factors include dry climate (Montana winters are particularly harsh), prolonged standing, obesity, flat feet, and systemic conditions including diabetes and hypothyroidism.

Treatment involves consistent moisturizing with urea-based creams (20–40% urea is most effective), debridement of hyperkeratotic edges, and addressing underlying dryness or biomechanical factors. Severely infected fissures may require antibiotics.

MRSA Awareness

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial strain resistant to many common antibiotics. Community-acquired MRSA can infect skin and soft tissue of the foot — particularly through cuts, puncture wounds, cracks, or insect bites. It often presents as a red, warm, rapidly enlarging painful lump or abscess that may be mistaken for a spider bite.

MRSA is not uncommon in active individuals who share equipment, facilities, or contact sports environments. If a skin infection on the foot is worsening despite initial antibiotics, not responding to typical treatment, or accompanied by fever, seek care promptly. Treatment involves culture-directed antibiotics (often trimethoprim-sulfamethoxazole or doxycycline) and, for abscesses, incision and drainage.

When to See a Podiatrist

Many nail and skin conditions are manageable at home in their early stages — but these situations warrant professional evaluation:

  • Any skin or nail concern in a patient with diabetes, peripheral arterial disease, or neuropathy
  • Signs of infection: increasing redness, warmth, swelling, pus, or streaking
  • Ingrown toenails that are painful, infected, or recurrent
  • Warts that are spreading, painful, or not responding to 2–3 months of OTC treatment
  • Toenail fungus involving multiple nails or causing pain and difficulty with footwear
  • Deep heel fissures that are bleeding or painful
  • Any rapidly worsening skin lesion