What is Athlete's Foot (Tinea)?
Athlete's foot is a disease caused by an infection of the skin's stratum corneum, nails, and hair by a type of fungus called dermatophyte. The name changes depending on the infected area; when it affects the feet, it is called tinea pedis, and when it affects the nails, it is called tinea unguium (nail fungus).
In Japan, it is a very common disease, with one in five people having tinea pedis and one in ten having tinea unguium. If left untreated, it can spread to family members, and in people with diabetes, it can become severe and lead to cellulitis. With a correct diagnosis and appropriate treatment, complete cure is possible.
Self-medication with over-the-counter drugs can be dangerous
If you suspect you have athlete's foot and apply an over-the-counter medication, you cannot confirm if it's truly dermatophyte. In many cases, applying antifungal medication to a simple rash or contact dermatitis can worsen the condition. At our clinic, we first confirm the presence of dermatophyte with a KOH direct microscopy test before starting treatment.
Types and Symptoms of Tinea
| Classification | Affected Area | Main Symptoms |
|---|---|---|
| Tinea Pedis (Athlete's Foot) | Between toes, sole of foot, heel | Itching, peeling skin, blisters, cracks |
| Tinea Unguium (Nail Fungus) | Toenails (rarely fingernails) | Nails become cloudy white to yellow, thicken, become brittle |
| Tinea Corporis (Ringworm) | Trunk, limbs | Annular red rash with central clearing tendency |
| Tinea Cruris (Jock Itch) | Groin, inner thighs | Severe itching, well-demarcated redness |
| Tinea Capitis (Scalp Ringworm) | Scalp, hair | Hair loss, scales, common in children |
| Tinea Manuum (Hand Fungus) | Palms, between fingers | Peeling skin, dryness (usually one hand) |
3 Types of Tinea Pedis
| Type | Characteristics | Peak Season |
|---|---|---|
| Interdigital Type | Moistness, peeling, and itching between toes (especially 4th-5th) | Summer to rainy season |
| Vesicular Type | Small blisters on arch and edge of foot, intense itching | Spring to summer |
| Hyperkeratotic Type | Heel and entire sole become thick, hard, and powdery (no itching) | Year-round (more noticeable in winter) |
Hyperkeratotic type is often overlooked
Since there is no itching, it is often mistaken for "mere dryness," but if persistent roughness on the heel continues, there is a possibility of hyperkeratotic athlete's foot. If left untreated, it can spread to the nails.
Diseases with Similar Symptoms to Athlete's Foot (Differential Diagnosis is Crucial)
Many diseases have symptoms similar to athlete's foot, and microscopic examination is essential for accurate diagnosis.
| Disease | Difference from Athlete's Foot |
|---|---|
| Dyshidrosis (Pompholyx) / Dyshidrotic Eczema | Also on sides of fingers and palms, bilateral, dermatophyte negative |
| Contact Dermatitis | Matches area of contact with causative substance |
| Palmoplantar Pustulosis | Pustules on palms and soles, sometimes accompanied by nail deformation |
| Psoriasis Vulgaris (Plantar Type) | Well-demarcated silver scales |
| Green Nail Syndrome (Pseudomonas aeruginosa) | Nail discolors green |
| Nail Psoriasis | Pitting, oil drop discoloration of nails, often accompanied by skin lesions |
| Subungual Hematoma | Red to purple discoloration of nail, history of trauma |
Diagnosis (KOH Direct Microscopy)
The definitive diagnosis of tinea is to confirm the presence of dermatophyte under a microscope. Our clinic performs this on the same day during outpatient visits.
KOH Direct Microscopy Procedure
- A small sample of suspicious skin or nail is collected with a scalpel or nail clippers (virtually painless).
- KOH (potassium hydroxide) is dropped on the sample to dissolve the skin, making the fungus easier to see.
- Dermatophyte hyphae (thread-like structures) are confirmed under a microscope.
- Time required: approximately 10-15 minutes.
Post-Confirmation Policy
- Dermatophyte confirmed → Treatment with appropriate antifungal medication begins.
- Negative (no dermatophyte) → Treatment for other diseases begins.
- If over-the-counter medication has already been used, re-examination is necessary after a 2-week discontinuation period.
Treatment Options
Tinea Pedis (Mainly Topical Medications)
| Medication (Representative Examples) | Characteristics |
|---|---|
| Luliconazole (Lulicon) | Once daily, effective against a wide range of dermatophytes |
| Terbinafine (Lamisil) | Once daily, strong fungicidal action |
| Butenafine (Mentax) | Once daily, penetrates stratum corneum well |
| Efinaconazole (Klenafin) | Topical solution for nails |
It is important to continue topical medication for 1-2 months even after symptoms disappear. Premature discontinuation is the biggest cause of recurrence.
Tinea Unguium (Oral Medication or Topical)
| Treatment Method | Duration | Efficacy/Characteristics |
|---|---|---|
| Oral Terbinafine | 6 months (toenails) | 70-80% cure rate, liver function monitoring required |
| Itraconazole Pulse Therapy | 3 cycles (3 months) | 1 week on medication → 3 weeks off, repeated |
| Fosravuconazole (Nailin) | 3 months | New generation, fewer drug interactions, 1 capsule daily |
| Topical Efinaconazole (Klenafin) | 48 weeks | When oral medication is difficult, cure rate lower than oral |
| Topical Luliconazole (Lunac) | 48 weeks | Same as above |
Oral medication is generally the primary treatment for tinea unguium
Tinea unguium is a disease that is difficult to cure completely with topical medications alone. Oral medication can achieve a 70-80% cure rate in 6 months, while topical treatment alone has a cure rate of less than 40%. Oral treatment is recommended for those who can take it.
Precautions for Oral Medications
- Liver function tests: Before starting, after 1 month, and every 1-2 months thereafter.
- Drug interactions (itraconazole has many contraindications with other drugs).
- Generally contraindicated during pregnancy and lactation.
- Severe liver disease or heart failure require cautious administration.
Treatment Duration and Recurrence
| Classification | Treatment Duration (目安) | Key to Preventing Recurrence |
|---|---|---|
| Tinea Pedis, Tinea Corporis | Topical for 3-6 months | Continue for 2 months after symptom disappearance |
| Tinea Unguium (Toenails) | Oral for 6 months / Topical for 48 weeks | Until new nail completely grows out |
| Hyperkeratotic Type | Topical + Oral for 6 months | Prioritize oral, topical alone is less effective |
Key Points to Prevent Recurrence
- Continue medication for the instructed period even after symptoms disappear.
- To prevent spreading to family, use separate slippers etc. during treatment.
- Bathe daily and wash thoroughly between toes.
- Keep shoes dry (do not wear the same shoes every day).
- Choose cotton or linen socks and change them frequently.
- Avoid sharing bath mats.
- Wash feet after going out barefoot.
Infection Prevention / Home Measures
Places in the Home Where Dermatophytes are Easily Transmitted
- Bath mats, towels
- Floors, tatami mats
- Shared slippers, footwear
- Corners difficult for vacuum cleaners to reach
Measures to Prevent Transmission
- Separate towels and bath mats for infected individuals.
- Infected individuals should bathe last.
- Wash bath mats frequently and sun-dry them.
- Vacuum indoors daily.
- Observe all family members' feet and seek medical attention for suspicious symptoms.
Dermatophytes are surprisingly difficult to adhere to
Even if dermatophytes adhere to the skin, it is said that infection will not occur if washed off within 24 hours. "Daily bathing and foot washing" is the greatest preventative measure.
Caution for Diabetics
For diabetics, athlete's foot can lead to serious infections
Diabetics have weakened immune systems, so there is a risk that cracks from athlete's foot can develop into cellulitis or gangrene. It is important not to dismiss even mild athlete's foot and to actively seek treatment.
- Habit of daily foot observation
- Do not injure yourself when trimming nails (consider using a podiatry clinic)
- Beware of burns and injuries
- Maintain good blood sugar control
Features of Our Clinic's Athlete's Foot Treatment
- KOH microscopic examination performed on the same day, allowing for accurate diagnosis.
- Selection of topical medications (luliconazole, terbinafine, etc.) according to symptoms.
- 対応New generation oral medications such as fosravuconazole (Nailin) are available for tinea unguium.
- Thorough liver function monitoring during oral medication.
- Comprehensive management for cases complicated by diabetes, with internal medicine collaboration.
- Family check-ups and infection prevention guidance also provided.
- No appointment necessary / Same-day consultation OK / Open 9:00-21:00 daily / 1-minute walk from Jujo Station.
Don't just think "it's just athlete's foot"
If athlete's foot is not completely cured, it will recur repeatedly and spread to family members. Let's cure it properly with accurate diagnosis and sufficient treatment duration.
