Athlete's Foot
​Tinea Pedis

Overview
Athlete’s foot (medically known as tinea pedis) is a superficial fungal infection of the the skin of the feet, typically caused by dermatophyte fungi (especially Trichophyton rubrum, T. interdigitale, and Epidermophyton floccosum)
It is one of the most common dermatologic foot conditions worldwide and can affect people of all ages, particularly those who frequent warm, moist environments (locker rooms, communal showers, swimming pools)
While it is usually benign and readily treatable, untreated or recurrent infection can lead to complications (e.g. bacterial superinfection, cellulitis) in at-risk populations (e.g. diabetes, immunocompromise)


Etiology & Risk Factors
Causative Organisms

• Dermatophyte fungi that feed on keratin in the superficial layers of skin
• Trichophyton rubrum is responsible for a large proportion of cases globally
• T. interdigitale and E. floccosum are commonly implicated as well

Pathophysiology

• Dermatophytes adhere to the stratum corneum (outer skin layer) via adhesive factors, then secrete proteolytic enzymes (keratinases) that digest keratin, allowing fungal invasion and persistence
• Warm, moist, occluded environments (e.g. between toes) facilitate fungal proliferation; skin maceration and microtrauma favor entry

Risk Factors

• Excessive sweating of the feet (hyperhidrosis)
• Wearing closed, tight, non-breathable footwear
• Walking barefoot in communal wet areas (locker rooms, showers, swimming pool decks)
• Sharing contaminated towels, footwear, or surfaces
• Prior fungal infections (e.g. toenail fungus)
• Immunosuppression, diabetes, peripheral vascular disease (higher risk of complications)
• Family clustering / household transmission (shared environment)

Clinical Presentation & Diagnosis
Common Clinical Patterns
Tinea pedis presents in several recognized clinical forms:

1. Interdigital type (most common)
   • Erythema, maceration, scaling, fissures (especially between toes, often 4th–5th web space)
2. Moccasin / hyperkeratotic type
   • Diffuse scaling, dry skin on plantar surfaces and sides of foot, resembling chronic dermatitis
3. Vesiculobullous (inflammatory) type
   • Blisters or pustules (vesicles) often on the sole or lateral foot, sometimes painful or itchy

Many patients may have mixed features or overlap with onychomycosis (fungal nail infection) or spread to the hands (tinea manuum)
Diagnostic Approach

• Clinical examination is often suggestive, but not always definitive.
• KOH (potassium hydroxide) preparation of skin scrapings (10–20 %) under a microscope can reveal septate hyphae and confirm dermatophyte infection
• Fungal culture may be obtained for species identification or in resistant/recurrent cases, though it takes longer.
• Molecular diagnostics (PCR) are emerging in specialized settings for faster and more specific identification

Differential diagnoses include eczema, contact dermatitis, bacterial intertrigo, psoriasis, and other dermatoses.


Treatment Options
The goal is to eradicate the fungus, alleviate symptoms, and prevent recurrence. Treatment is stratified by severity and extent of infection.
Topical Antifungals (First-line in most cases)

• Agents include allylamines (e.g. terbinafine), azoles (e.g. clotrimazole, ketoconazole), benzylamines, ciclopirox, tolnaftate, amorolfine
• The 2022 systematic review (Consensus for the Treatment of Tinea Pedis) found that topical terbinafine and butenafine were significantly more efficacious than placebo in randomized trials (e.g. RR ~3.9 for terbinafine)
• Duration often ranges from 1 to 6 weeks (typically 2–4 weeks) depending on the formulation and clinical response
• In hyperkeratotic forms, keratolytic agents (e.g. salicylic acid, urea) may assist penetration of the antifungal

Oral (Systemic) Antifungals
Reserved for more extensive, refractory, or recurrent disease, or when topical therapy fails, or when there is concomitant nail involvement or immunosuppression

• Common agents: terbinafine (oral), itraconazole, fluconazole
• In meta-analyses and trials, systemic terbinafine and itraconazole have shown superiority to placebo and are more effective in certain settings, though with a higher risk of side effects and need for monitoring

Adjunctive Measures & Hygiene

• Keep feet dry: thoroughly dry especially between toes after washing
• Use moisture-wicking socks (cotton or technical fabrics)
• Change socks daily (or more often if sweaty)
• Alternate pairs of shoes to allow drying
• Use antifungal powders or sprays in shoes and on feet (especially between toes)
• Wear breathable footwear (open mesh, natural materials)
• In communal areas, use flip-flops or sandals in showers / locker rooms
• Treat coexisting onychomycosis or fungal reservoirs
• Prevent re-inoculation, e.g. disinfect shower surfaces, socks, footwear

Recurrent or Refractory Cases

• Consider combination therapy (topical + systemic)
• Reassess diagnosis (possible mixed infection, non-dermatophyte mold or resistant strain)
• Longer duration therapy or maintenance regimens
• Address predisposing factors (e.g. hyperhidrosis, immunosuppression)

Expectations & Prognosis

• With appropriate treatment, most cases resolve clinically and mycologically within weeks to a few months
• Recurrence is common (tinea pedis is known for relapse), so preventive hygiene and environmental measures are critical
• In mild to moderate cases, cure rates with topical antifungals are high (especially with allylamines)
• In more extensive disease or in patients with comorbidities, systemic therapy may improve outcomes but carries higher risks
• If untreated, chronic infection may persist, and complications (bacterial superinfection, cellulitis, ulceration) can occur—especially in high-risk individuals (e.g. diabetics)
• Prognosis is generally good, provided that infection is properly treated, adherence is good, and preventive measures are followed

Key Takeaways

• Athlete’s foot is a common, treatable fungal infection of the foot skin.
• Diagnosis is largely clinical but supported by KOH microscopy and fungal cultures in uncertain cases.
• Topical antifungals are first-line; systemic agents are reserved for severe or refractory cases.
• Because recurrence is common, hygiene, shoe drying, and preventive foot care are essential.
• Prompt therapy minimizes risk of complications, especially in vulnerable populations.

References

1. Leung AKC, Barankin B, Lam JM, Leong KF, Hon KL. Tinea pedis: An updated review. Drugs Context. 2023;12:2023-5-1.
2. Ward H, et al. Consensus for the Treatment of Tinea Pedis: A Systematic Review. J Fungi. 2022;8(4):351.
3. Prens L, et al. Topical treatments for tinea pedis: Preliminary analysis. J Am Acad Dermatol. (abstract)
4. “Tinea pedis: an updated review.” PMC. (Leung et al)
5. “Tinea pedis — an embarrassing problem for health and ...” Mycoses (review)​