Dermatology & Podiatry & Family Medicine
Athlete's foot (tinea pedis)
Obtenir un avis adapté à votre situation
Consultation en clinique ou en téléconsultation, partout au Québec.
Athlete's foot—a common term for tinea pedis or foot dermatomycosis—is the most common dermatophytosis (skin infection caused by dermatophytes) in the world, affecting approximately 15 to 25% of the general population at some point in their lives, with a higher prevalence among adult men, athletes, people who regularly use public swimming pools and locker rooms, and in diabetic or immunocompromised patients. In the vast majority of cases, it is caused by dermatophytes of the genus Trichophyton - mainly Trichophyton rubrum (70 to 80% of cases) and Trichophyton interdigitale (formerly T. mentagrophytes variable. interdigital, 15–25 %) — which are exclusively keratinophilic fungi, meaning they are capable of breaking down the keratin in the stratum corneum of the epidermis, nails, and hair using their keratinases, without ever invading the underlying living tissue except in cases of severe immunosuppression. Transmission occurs directly between humans (through contact with infected skin flakes) or indirectly through contact with contaminated surfaces—swimming pool floors, shower stalls, locker rooms, gym mats—where dermatophytes can survive in keratinized skin flakes for several weeks to months. Maceration caused by sweating in closed shoes is the main predisposing factor in the absence of group exposure, creating a warm, humid environment ideal for fungal growth. Tinea pedis is clinically significant not only for its local manifestations—interdigital pruritus + desquamation + fissures—but also because it serves as the primary reservoir and entry point for onychomycosis (see dedicated fact sheet) and, in patients with diabetes or peripheral artery disease, can promote bacterial superinfections, cellulitis, and serious foot complications.
Clinical forms
| Clinical form | Location and appearance | Fungal agent and frequency |
|---|---|---|
| Interdigital form (the most common — 60–70 %) | Interdigital space between the 3rd and 4th toes (or 4th and 5th) → whitish maceration + scaling + painful fissures + intense itching + unpleasant odor + can extend to the plantar surface. The «dry» form presents fine scaling without maceration. The «weeping» (dyshidrosiform) form presents white maceration with an unpleasant odor and deep fissures. | T. interdigitale predominant for macerated form + T. rubrum for dry form + easiest form to treat + quick response (1-2 weeks) to topical antifungals |
| Plantar hyperkeratotic form (moccasin — 20–25 %) | Diffuse dry, floury hyperkeratosis of the entire plantar surface, heels, and lateral edges of the foot in a «moccasin» appearance, with fine, adherent whitish scales. Pruritus is often absent or moderate, with a chronic appearance. Often bilateral and frequently associated with onychomycosis. | T. rubrum quasi-exclusive + chronic relapsing form + less responsive to topicals alone (thick hyperkeratosis) → often requires systemic antifungal (oral terbinafine) |
| Vesicular or dyshidrotic form (10–15 %) | Pruritic vesicles + sometimes bullous + on the sole of the foot + lateral edge of the feet + interdigital spaces + vesicles may coalesce into bullae + clear initially then cloudy content + spontaneous rupture → crusts + erosions + sometimes distant hypersensitivity reaction (dermatophytid — allergic reaction to fungal antigens) | T. interdigitale variable. Mentagrophytes most inflammatory form + can mimic dyshidrotic eczema or contact dermatitis + secondarily infected by bacteria (staphylococci) |
| Ulceronecrotic form (rare — immunocompromised patients) | Ulcerations + necrosis + severe bacterial superinfection + extension to deep tissues + in diabetic patients + AIDS patients + chemotherapy | T. rubrum + T. interdigitale + often polymicrobial with bacterial superinfection + requires systemic antifungal + IV antibiotic therapy + intensive local care + risk of diabetic foot osteomyelitis |
Diagnosis
- Clinical diagnosis: In the vast majority of cases, the clinical presentation is characteristic enough to initiate treatment without mycological confirmation: itching, scaling, interdigital maceration, or diffuse plantar hyperkeratosis in a patient at risk (athlete, swimmer, diabetic) = probable tinea pedis → immediate topical antifungal treatment
- Direct microscopic examination (KOH): KOH 20–40 % scale clarification + visualization of mycelial hyphae under a microscope + results in 30 minutes + confirms the presence of fungi but does not allow for species identification + indications: atypical form + diagnostic uncertainty + form resistant to standard treatments + perform before any culture (collect scales from the most active area—edge of lesions)
- Sabouraud's medium culture: Precise identification of the fungal species + results in 3 to 4 weeks + useful if it's a resistant form + if an unusual species is suspected + or if systemic treatment is considered
- Differential diagnosis : Contact or atopic eczema (patch testing + RAST + atopic context) + plantar psoriasis (well-defined plaques + erythematous-squamous + psoriatic nail involvement + APS) + palmoplantar keratoderma (hereditary + bilateral since childhood) + erythrasma (bacterial with Corynebacterium minutissimum — coral fluorescence under a Wood's lamp)
Antifungal treatment
| Treatment | Molecule, formulation, and protocol | Efficacy and indications |
|---|---|---|
| Terbinafine Cream 1% — first-line topical treatment | Apply 1x/day × 7 days (interdigital form) or × 2 weeks (plantar form) + apply a thin layer to affected areas and 1 cm beyond + available without a prescription (Lamisil® AT + generics) + mechanism: squalene epoxidase inhibitor → fungicidal | Mycological cure rate: 70–90% (%) for interdigital tinea pedis + fungicidal activity (kills fungi) vs. fungistatic activity of azoles + shortest effective treatment duration for the interdigital form + few side effects (mild local irritation possible) |
| Clotrimazole cream 1% (Canesten®) | Application 2 times/day × 4 weeks + available without a prescription + mechanism: ergosterol synthesis inhibitor (azole) → fungistatic | Response rate 65–80% % + longer treatment duration than terbinafine + good local tolerance + also effective on Candida (useful if a candidal superinfection is associated) + option for patients intolerant to terbinafine |
| Topical Miconazole + Econazole + Ketoconazole | Apply 1–2 times daily for 2–4 weeks + azole-based (fungistatic) agent + ketoconazole 2% cream or shampoo (effective for associated tinea versicolor) | Comparable efficacy to clotrimazole + azoles in general + longer treatment duration than terbinafine + miconazole powder or spray is useful as an adjunctive treatment for shoes (reduced recontamination) |
| Oral Terbinafine (Lamisil® 250 mg) — resistant or severe forms | 250 mg/day × 2 weeks for tinea pedis (or 1 week for interdigital forms only) + with or without food + indicated for moccasin-type hyperkeratotic plantar presentation resistant to topicals + very extensive or recurrent forms + immunosuppression | Mycological cure rate > 90% (%) for topical-resistant forms + possible systemic side effects (nausea, headache, dysgeusia, rare hepatotoxicity) + liver function tests if treatment lasts > 6 weeks + drug interactions (CYP2D6 inhibitors) |
Relapse prevention
- Foot hygiene : Daily washing of the feet with soap and water + careful and thorough drying between the toes (the area most prone to maceration and fungal growth) + cut nails short and straight + regularly inspect the spaces between the toes
- Shoes and socks: Cotton socks or breathable natural fibers (prefer over synthetics which retain moisture) + change socks daily + rotate shoes to allow them to dry completely between uses (at least 24 to 48 hours) + antifungal powders or sprays (miconazole + tolnaftate) in shoes to reduce fungal flora
- Collective environments Wear flip-flops or shower shoes in pools, locker rooms, communal showers, and saunas. Never walk barefoot on wet communal floors. Disinfect home shower stalls regularly.
- Concurrent treatment of onychomycosis: Tinea pedis often recurs from the fungal reservoir of infected nails → simultaneously treat onychomycosis if present (see dedicated sheet) + without treatment of onychomycosis, tinea pedis is almost certain to recur within weeks to months after stopping topical treatment
- Household member treatment: family members using the same showers or bedding may reinfect each other → if a household member has recurrent tinea pedis despite correct treatment → screening of other members + preventive treatment with antifungal powder in shared shoes
ℹ️
Tinea pedis (athlete's foot) is the primary source of nail infection for onychomycosis—approximately 30 to 40% of patients with untreated tinea pedis will develop onychomycosis in the following years. Conversely, the presence of onychomycosis perpetuates tinea pedis even after topical treatment of the foot. Treatment of tinea pedis should therefore always include an examination of the nails, and if onychomycosis is present, simultaneous treatment is essential to prevent recurrence of athlete's foot.
Situations requiring medical consultation
Consult a doctor quickly if athlete's foot spreads rapidly, is accompanied by redness extending up the leg (lymphangitis - ascending red streak), significant swelling, pus, or fever. These signs indicate a bacterial superinfection (cellulitis, erysipelas) requiring urgent systemic antibiotic therapy. In a diabetic patient, any athlete's foot with cracks or skin lesions should be evaluated by a doctor quickly, even without apparent signs of infection, due to the risk of serious complications (entry point for deep cellulitis or diabetic foot osteomyelitis).
For the diagnosis and treatment of athlete's foot resistant to over-the-counter antifungals, prescribing an oral antifungal if indicated, and referral to dermatology or podiatry for complex cases, Clinique Omicron offers medical consultations at its service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's physicians and nurse practitioners (specialists) diagnose and treat athlete's foot in its various clinical presentations. They prescribe oral terbinafine for forms that are resistant to topical treatments or for hyperkeratotic (moccasin-type) presentations, treat bacterial superinfections if present, assess and treat associated onychomycosis, and provide advice on hygiene and prevention of recurrence. Consultations are available at several service locations in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not replace the advice of a doctor or dermatologist. In diabetic patients, any foot lesion — even if seemingly minor — must be medically evaluated because complications can be serious and develop rapidly due to associated neuropathy and vasculopathy.
Omicron Clinic
Need to consult a doctor?
En clinique ou en télémédecine, partout au Québec.
Reçus pour assurances. Téléconsultation 7 j/7. Sans médecin de famille requis.