OVERVIEW

What is tinea pedis?

Tinea pedis, also known as "athlete's foot," is a common skin disease caused by fungal infection of the skin on the feet^[1].

Tinea pedis often leads to maceration between the toes, presenting as blisters, whitening, and peeling skin, particularly between the 3rd–4th and 4th–5th toes, accompanied by itching and stinging. Additionally, thickened skin, scaling, and bleeding from cracks may occur on the soles, heels, and sides of the feet.

Mild cases of tinea pedis can usually be treated with topical medications, while stubborn cases may require oral antifungal drugs under the guidance of a dermatologist. Tinea pedis tends to recur, so maintaining clean and dry feet is essential during and after treatment.

What is beriberi?

The true medical condition referred to as "beriberi" is "vitamin B1 deficiency," which has no relation to tinea pedis.

Beriberi is a systemic disease caused by vitamin B1 deficiency, often occurring in regions where polished white rice is the staple food, though it is now relatively rare.

Vitamin B1 deficiency primarily affects the nervous, cardiovascular, and digestive systems. Neurological symptoms include abnormal sensations, neuralgia, limb weakness, muscle pain, and atrophy. Cardiovascular symptoms include palpitations, shortness of breath, chest tightness, and cardiac hypertrophy. Digestive symptoms mainly involve reduced appetite, leading to weakness and weight loss.

Severe cases may also experience heart failure, generalized edema, pleural effusion, and ascites.

What are the types of tinea pedis?

Based on clinical manifestations, tinea pedis can be classified into the following types^[1]: vesicular, squamous hyperkeratotic, and intertriginous erosive. These types may coexist at different stages of the disease.

• The vesicular type is characterized by distinct pinhead-sized blisters with significant itching.
• The squamous hyperkeratotic type mainly involves rough, cracked skin prone to bleeding.
• The intertriginous erosive type primarily presents with erosions, noticeable itching, and fluid discharge.

Which department should tinea pedis patients visit?

Dermatology.

SYMPTOMS

What are the manifestations of athlete's foot?

Different types of athlete's foot present differently, as follows:

1. Vesicular type: Commonly seen between the toes or on the midfoot, rarely on the heel. Initially, there are scattered or clustered pinpoint-sized blisters filled with clear fluid, accompanied by noticeable itching or stinging. After the blisters dry and are absorbed, peeling occurs.
2. Intertriginous erosive type: Often appears between the toes, especially the 3rd–4th and 4th–5th toe webs. The skin becomes macerated, white, and eroded; removing the whitened layer reveals a red, eroded surface, sometimes with oozing. Severe itching is common, and a foul odor may develop if bacterial infection occurs.
3. Squamous hyperkeratotic type: Mostly affects the soles, heels, and dorsum of the foot. Symptoms include rough, thickened, dry, and scaly skin, usually without significant itching. Cracking may lead to bleeding and pain^[1,2].

Why is athlete's foot so intensely itchy?

The degree of itching varies among individuals—some barely notice it, while others experience severe itching.

The itching may result from inflammation and the release of substances like histamine triggered by fungal growth. When histamine enters the bloodstream, it can cause itching.

Does foul foot odor always mean athlete's foot?

Not necessarily. Ordinary foot odor arises from excessive sweat gland secretion. While sweat itself is odorless, bacterial breakdown of sweat components produces unpleasant smells, worsened by poor foot hygiene.

Athlete's foot, however, is caused by fungal infection. If the feet sweat excessively, fungi multiply and break down keratin, generating odor.

Thus, athlete's foot often accompanies foot odor, but foot odor doesn’t always indicate athlete's foot.

Why is athlete's foot worse in summer?

Warm, humid environments promote fungal growth, making summer—especially the rainy season—the peak time for athlete's foot. This also explains why southern China has higher incidence rates than the north^[2].

Why does athlete's foot recur easily?

High recurrence rates are mainly due to inadequate treatment, incomplete disinfection of footwear, damp local conditions, and cross-infection^[3].

1. Inadequate treatment: Topical antifungals may fail due to uneven application or poor penetration, leading to relapse. Oral medications stopped prematurely also increase recurrence risk.
2. Incomplete disinfection: Fungi have protective capsules that resist ordinary cleaning. If footwear isn’t thoroughly disinfected, fungi can reattach and reinfect the skin.
3. Damp conditions: Sweaty feet in non-breathable shoes create an ideal fungal environment, raising recurrence chances.
4. Cross-infection: Recurrence may occur if cured patients resume unhygienic habits like sharing footwear.

Why is athlete's foot often accompanied by jock itch?

Superficial fungal infections can spread to other body parts. Scratching the feet and then touching the inner thighs or groin may transfer the fungus, causing jock itch.

CAUSES

What are the causes of athlete's foot?

Athlete's foot is primarily caused by a combination of fungal infection, individual factors, and environmental conditions.

1. Fungi: It is mainly caused by dermatophyte infections, with Trichophyton being the most common, particularly Trichophyton rubrum and Trichophyton mentagrophytes.
2. Individual and environmental factors: The soles and between the toes lack sebaceous glands, resulting in insufficient fatty acids to inhibit fungal growth and weaker physiological defenses. These areas, however, have abundant sweat glands, leading to excessive sweating. Combined with poor air circulation and a warm, moist environment, these conditions promote fungal growth^[3,4].

How is athlete's foot usually transmitted? What are the routes of transmission?

Athlete's foot is primarily transmitted through direct or indirect contact with dermatophytes. It can spread between people, animals and humans, or contaminated objects and humans, such as:

1. Sharing shoes or socks with an infected person, walking barefoot in public places like locker rooms, gyms, or swimming pools where fungal infections exist, or other close contact with pathogens.
2. It can also spread to other body parts, such as causing hand fungus, nail fungus, or ringworm. Over one-third of athlete's foot patients also have nail fungus.

Additionally, hot and humid regions or seasons with excessive foot sweating and moisture increase the likelihood of infection.

Why is athlete's foot more common among students?

Young people, especially students, tend to be active and sweat more, keeping their feet in a damp state that fosters fungal growth and reproduction.

Students often live in group settings, sharing dormitories, bathrooms, or even footwear, which facilitates the spread of athlete's foot.

Why is athlete's foot more likely to occur in people with diabetes?

Diabetic patients often experience metabolic disorders, leading to the accumulation of glycation byproducts and weakened immune function, making them more susceptible to fungal infections like athlete's foot.

Why is athlete's foot common among people who frequently get manicures or pedicures?

If performed in public settings using non-disposable or unsterilized tools, manicures and pedicures may expose individuals to fungal pathogens.

Additionally, procedures like cutting and filing, along with excessive use of chemicals, can damage the skin around the nails, creating opportunities for fungal infections.

Is athlete's foot more likely to occur in people with weakened immunity?

Yes.

Conditions like immunodeficiency, prolonged use of certain medications (e.g., corticosteroids, anticancer drugs), or post-organ transplant immunosuppressants often lower immunity, reducing resistance to fungal infections. This increases the risk of athlete's foot and may worsen existing infections.

Is athlete's foot more common among people who frequently wear high heels?

Yes.

High heels or tight shoes increase pressure on the forefoot and squeeze the toes, leading to skin damage and excessive moisture between toes, creating an ideal environment for fungal growth.

If not necessary for work or daily life, giving your feet regular breaks can help reduce the risk of infection.

DIAGNOSIS

What tests are needed to diagnose athlete's foot?

Diagnosing athlete's foot is relatively straightforward. Doctors can usually confirm it based on typical symptoms and mycological examination results, which include fungal microscopy and culture.

1. Fungal microscopy: The doctor will scrape some skin flakes from the affected area, process them, and examine them under a microscope. If pathogenic fungi are detected, the result is positive.
2. Fungal culture: Since athlete's foot symptoms may resemble other fungal infections, fungal culture can help identify the pathogen if microscopy is inconclusive. Skin flakes are placed in a culture medium, and if fungi grow, the result is positive. Further species identification is then performed to determine the specific pathogen^[1,2].

What is the relationship between athlete's foot and onychomycosis?

Onychomycosis, also known as "tinea unguium," can be caused by dermatophytes, yeasts, or non-dermatophyte molds, most commonly Trichophyton rubrum, which is also the primary pathogen of athlete's foot.

The causative fungi of onychomycosis usually originate from the patient themselves. Most patients first develop tinea pedis (athlete's foot) or tinea manuum (hand fungus) before developing onychomycosis^[5].

Because nails lack cellular immune function, they are easily infected by fungi, and the nail plate provides an ideal environment for fungal survival. However, compared to the skin of the hands and feet, nails have stronger defensive capabilities.

Therefore, patients typically first develop fungal infections on the skin of their hands or feet, which then spread to the nails.

What is the relationship between athlete's foot and dermatophytid?

Dermatophytid is an allergic inflammatory reaction of the skin to a dermatophyte infection^[6].

Fungal antigens released from the infection site of athlete's foot enter the bloodstream and spread to surrounding or distant skin, triggering an antigen-antibody reaction. This leads to itchy erythema, papules, or vesicular lesions.

Dermatophytid appears as the primary fungal infection develops and gradually resolves as the infection is treated.

What is the relationship between athlete's foot and erysipelas?

If patients with athlete's foot do not take proper care, bacteria may enter subcutaneous tissue or lymphatic vessels through broken skin, causing infections such as erysipelas.

Erysipelas typically develops rapidly, initially presenting as redness, swelling, heat, and pain on the foot or lower leg. As it progresses, the infection spreads, forming a clear boundary with unaffected skin.

What is the difference between athlete's foot and foot eczema?

Athlete's foot commonly presents with erythema and blisters, with more severe lesions at the edges due to the outward spread of fungi. In contrast, foot eczema often shows more severe lesions in the center.

Athlete's foot usually starts between the toes, where moisture and lack of airflow favor fungal growth. Foot eczema, however, typically occurs in areas other than the toe webs, such as the heel, arch, or dorsum of the foot.

Athlete's foot tends to recur cyclically, such as in hot weather or with prolonged sweating and moisture. Foot eczema also recurs but without a clear pattern.

Both conditions may cause itching. In athlete's foot, itching is often intense in the early stages but may lessen or disappear as the skin thickens and cracks^[1,2].
Most importantly, fungal tests for foot eczema are negative, while they are positive for athlete's foot.

TREATMENT

Can Soaking Feet in Vinegar Cure Athlete's Foot?

Soaking feet in vinegar alone is almost impossible to fundamentally cure athlete's foot. Even if symptoms disappear, they may recur.

Vinegar mainly consists of 2%~9% acetic acid. Theoretically, an acidic environment can inhibit fungi, and in daily life, some people use mixed solutions of acetic acid or aluminum acetate to assist in treating athlete's foot to reduce recurrence. However, this is at best an auxiliary measure—inhibiting fungi does not equate to killing them. Even if symptoms alleviate, it only addresses the surface; eradicating the fungi is the root solution.

To completely eliminate fungal issues, using professional antifungal medication is the preferred approach, while also ensuring the skin remains dry and breathable. It is recommended to seek treatment under a doctor's guidance to avoid unnecessary setbacks.

Can Athlete's Foot Heal on Its Own? Is Treatment Necessary?

It generally cannot heal on its own and requires treatment. Without proper and active intervention, it may spread to other parts of the body or infect others.

What Are the Treatment Methods for Athlete's Foot?

Treatment primarily includes topical and oral medications. Different patients should choose appropriate plans based on their specific conditions.

In most cases, mild athlete's foot (e.g., minimal skin damage, mild itching) can be treated with topical medications, which are effective and cost-efficient. Common options include:

• Azole antifungals: such as miconazole cream, ketoconazole cream, clotrimazole cream, etc.
• Allylamine antifungals: such as terbinafine hydrochloride cream or spray, butenafine hydrochloride spray, etc.

Other options include amorolfine and ciclopirox olamine.

Note that the choice should be tailored to the condition, for example:

• For vesicular types, non-irritating solutions or creams are recommended;
• For intertriginous/erosive types, powders should be used first until the surface dries, followed by creams;
• For scaly/hyperkeratotic types, creams or ointments are suitable.

When applying, cover not only the affected area but also the surrounding skin. Wait for the medication to absorb before wearing socks or shoes. Some medications require only once-daily application, preferably before bedtime for convenience. Follow the doctor's advice or the instructions. Even after symptoms disappear, continue treatment for 1–2 weeks to ensure complete eradication of the fungi.

For extensive, severe cases or if topical treatments are ineffective, oral medications may be considered. Common options include terbinafine and itraconazole, which may cause side effects like headaches, diarrhea, or fever and should be taken under medical supervision^[1,2]. If necessary, doctors may recommend combining oral and topical treatments.

How to Treat Athlete's Foot with Localized Redness, Swelling, Heat, and Pain?

These symptoms suggest a possible bacterial infection, such as cellulitis. This is urgent and requires prompt medical attention. A doctor will assess the severity and prescribe appropriate measures, which may include oral or intravenous antibiotics.

DIET & LIFESTYLE

What should patients with athlete's foot pay attention to in their diet?

Athlete's foot is not directly related to diet. A healthy and balanced diet is recommended. There is no need for blind dietary restrictions, as they often provide no additional benefits. "Dietary supplements" or "food therapy" are also unnecessary.

What should patients with athlete's foot pay attention to in daily life?

Athlete's foot is highly contagious and prone to recurrence. The following points should be noted in daily life:

1. Wear breathable shoes and socks, keep the skin of the feet dry and clean, and change socks frequently.
2. Foot basins, towels, bath towels, and nail clippers should be used separately to avoid spreading the infection.
3. In hot weather, open-toed shoes are preferable. Avoid wearing non-breathable shoes to prevent excessive sweating, which can worsen the condition.
4. Those with tightly spaced toes can place clean gauze or cotton balls between the toes to absorb moisture and improve ventilation.

PREVENTION

How to Prevent Athlete's Foot?

Since athlete's foot is associated with factors like moisture and contagion, prevention should focus on these two aspects, which largely align with daily precautions.

1. Maintain personal hygiene. Dry the spaces between toes thoroughly after washing feet, and wear breathable shoes and socks. Replace and air out damp footwear promptly. Shoes can be sun-dried or disinfected using short-wave ultraviolet light (a dedicated UV shoe sterilizer can be purchased).
2. Avoid using public facilities with poor sanitary conditions, such as shared baths, foot-soaking tubs, or pedicure services, to reduce infection risks.
3. Use personal slippers in public areas like locker rooms and bathrooms. Avoid sharing shoes, socks, nail clippers, bathtubs, towels, or other personal items to minimize indirect transmission.
4. Promptly treat fungal infections on other body parts to prevent spreading to the hands, groin, etc.
5. Avoid staying up late, engage in moderate physical exercise, and boost immunity.