Athlete’s Foot – Diagnosis, Symptoms, and Treatment

What is Athlete's Foot?

Fungal skin infections are common and can affect various portions of the body, including the nails, groin, feet - athlete's feet, and head.  Individuals frequently have a simultaneous presence of fungal skin infection in more than one body region.  These infections are typically caused by dermatophytes such as Epidermophyton, Trichophyton, and Microsporum.  These fungi usually produce superficial skin infections that involve only the outer epidermal layer.  Dermatophytes, yeast, or molds can cause nail infections.

The manifestations of fungal skin infection depend on the particular body region affected.  Skin lesions tend to be circular, red, scaly, and itchy.  Nail infections usually produce discolored nails that are brittle and crusty.  Physicians can treat most superficial fungal skin infections with topical antifungal therapies, but others require oral medications.

What Causes an Athlete's Foot?

Fungal skin infections are typically acquired by direct contact with the causative fungus.  These fungi typically include dermatophytes such as Epidermophyton, Trichophyton, and Microsporum.  Tinea pedis (fungal foot infection) can be caused by contact with fungi while walking barefoot in a locker room or swimming pool facility.  Tinea corporis (fungal body surface infection) often occurs in outbreaks among athletes with skin-to-skin contact (e.g., wrestlers).  Dermatophytes, yeast, or molds usually cause fungal nail infections (tinea unguium).

The following is a list of medical terms for fungal infection involving various body regions:

• Tinea corporis – infection of body surfaces such as the trunk, back, or abdomen
• Tinea pedis – fungal foot infection (athlete's foot)
• Tinea cruris – fungal groin infection (jock itch)
• Tinea capitis – fungal scalp infection
• Tinea unguium – fungal nail infection (onychomycosis)

How Common is Athlete's Foot?

Fungal skin infections are prevalent in the United States and responsible for frequent primary care visits.  They may require referral to dermatology or infectious disease specialist if first-line measures are unsuccessful.

The most common fungal skin infections include tinea unguium (about 39% of cases), tinea corporis (approximately 23% of cases), and tinea pedis (about 20% of cases).  Tinea unguium and corporis appear to be more predominant in women, whereas tinea pedis and cruris are more prevalent in men.

Signs and Symptoms 

Tinea pedis (fungal foot infection) tends to cause itchy (pruritic), red (erythematous), erosions, and scales between toes.  Patients may develop painful fissures between the toes as well.

Tinea corporis typically manifests as itchy, circular, red, scaly plaques that spread outward.  They usually have central clearing and raised borders.  This is why this condition is commonly referred to as “ringworm.”

Tinea cruris (“jock itch”) is characterized by a red patch on the inner thigh that spreads outwards and has a central clearing.  Its border may have tiny vesicles or “blisters.”  The infection can spread to areas around the groin or buttocks.

Tinea unguium (onychomycosis) is characterized by nail discoloration (yellow/brown) and separation of the nail plate from the nail bed.

Diagnosis

Fungal skin infections are typically diagnosed based on symptoms and physical examination findings.  Testing is often performed to confirm the diagnosis as many skin conditions have a similar appearance.

Skin scrapings are usually analyzed on a potassium hydroxide (KOH) preparation.  Fungal cultures are also occasionally sent for diagnostic confirmation.  Inaccurate diagnosis of fungal skin infection can result in inappropriate therapy with topical corticosteroids (e.g., Cortizone cream).

Athlete's Foot Medication and Treatment

The majority of fungal skin infections improve with topical antifungal therapy.  Individuals with tinea pedis, tinea corporis, or tinea cruris usually benefit from topical agents such as:

• Clotrimazole
• Spectazole (econazole)
• Jublia (efinaconazole)
• Ketoderm (ketoconazole)
• Lamisil (terbinafine)
• Ciclodan (ciclopirox)
• Lotrimin Ultra (butenafine)
• Tinactin (tolnaftate)

Patients with tinea pedis and tinea cruris often have recurrent infections.  Individuals with tinea pedis should generally use drying foot powders to reduce moisture and risk for fungal reinfection.  Placement of antifungal foot powders in footwear and avoidance of occlusive shoes may also be useful.  Tinea cruris can also benefit from desiccating powders in the groin and avoidance of occlusive clothing.

Oral antifungal medications are typically reserved for severe infections or those that have not responded to topical agents.  Oral antifungal drugs such as Lamisil (terbinafine) or Sporanox (itraconazole) are typically required for nail infections (onychomycosis).

References:

1. Ameen M. Epidemiology of superficial fungal infections. Clin Dermatol 2010; 28:197. - https://www.ncbi.nlm.nih.gov/pubmed/20347663
2. Crawford F, Hollis S. Topical treatments for fungal infections of the skin and nails of the foot. Cochrane Database Syst Rev 2007; :CD001434. - https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001434.pub2/full
3. El-Gohary M, van Zuuren EJ, Fedorowicz Z, et al. Topical antifungal treatments for tinea cruris and tinea corporis. Cochrane Database Syst Rev 2014; :CD009992. - https://www.ncbi.nlm.nih.gov/pubmed/25090020