Fungal infection

Disease Description (Causes and Symptoms)

• Definition: A superficial fungal infection that affects the stratum corneum, fingernails/toenails, and hair (e.g., tinea capitis, tinea corporis, tinea cruris, tinea pedis, and tinea unguium).
• Causes: Fungi present on the skin and in the environment (dermatophytes [filamentous fungi] and yeasts) multiply under favorable conditions such as excessive moisture, friction, and reduced immunity. Fungal spores can survive in the environment for long periods.
• Pathophysiology: Fungi invade the stratum corneum and form hyphae or multiply like yeast, destroying the stratum corneum and causing inflammation. Depending on the infected area, localized itching, peeling or scaling, fissures, blisters, and nail discoloration or thickening may occur.
• Main symptoms: Skin scaling, cracking between the toes (especially with tinea pedis), splitting and deformity of the fingernails/toenails (tinea unguium), and itching (skin pruritus). Differential diagnosis is possible based on the form and distribution of the lesions.

Treatment Methods

• Diagnostic approach
  • Microscopy: KOH preparation (treating skin, scale, or nail scrapings with KOH and observing hyphae) — rapid and widely used.
  • Culture: Fungal culture (helps identify the species and perform antifungal susceptibility testing).
  • Histology/PCR: When necessary, supportive diagnosis with PAS-stained tissue examination or molecular testing.
• Topical treatment
  • Mild or localized lesions: Topical antifungals (azoles: clotrimazole, miconazole, etc. / allylamines: terbinafine cream, etc.) for at least 2–4 weeks (varies depending on the site and medication). Keep the affected area dry and well ventilated.
  • Moisturizers and keratolytics may be used together (in cases of hyperkeratosis).
• Systemic treatment
  • For tinea unguium, extensive or recurrent infections, or hair involvement: Oral antifungals
    • Oral terbinafine: Recommended for 6–12 weeks for fingernail tinea and 12 weeks for toenail tinea (liver function tests are required).
    • Oral itraconazole: Pulse or continuous therapy; caution regarding drug interactions.
    • Oral fluconazole: Used in some cases.
  • Treatment may be prolonged depending on the location and depth of the lesion, and fingernails/toenails may take several months to fully grow out normally.
• Procedures and surgery
  • Nail removal (topical or surgical) may be considered for severe tinea unguium (if conservative treatment fails).
• Lifestyle management and supportive care
  • Wash the feet frequently and keep them dry; dry thoroughly between the toes.
  • Use well-ventilated shoes and socks, and limit the use of stockings and enclosed shoes.
  • Do not share towels, shower room chairs, or shoes; disinfect household items.
• Considerations for pregnancy, liver disease, and drug interactions
  • Oral medications (especially itraconazole) have drug interactions and contraindications (including pregnancy), so consult a doctor.

Outpatient Visit Checklist (Including Preparations and Example Questions)

• What to bring
  • A list of all medications currently being taken (including prescription drugs, over-the-counter drugs, herbal medicines, and supplements)
  • Medical history: liver disease, allergies, pregnancy, or underlying medical conditions
  • Results of recently performed tests (such as liver function tests), or medical records and photographs
  • When symptoms started, changes in symptoms (whether they have spread, worsened, or improved), treatment history, and medications used (drug names and duration)
  • Photographs of the affected areas (overall and close-up), and lifestyle information such as shoe and sock-wearing habits
• Materials helpful to provide to the doctor during the outpatient visit
  • A symptom progression diary (times when itching is severe and aggravating factors)
  • Previous skin or fungal test results (if available)
• Example questions to ask during the visit (including items patients may ask themselves)
  • Are there any medications or treatments I should stop or avoid to relieve my current symptoms?
  • What preliminary tests and monitoring are needed if an oral antifungal is prescribed?

General Example Questions to Ask the Doctor

• What are the common and rare side effects of this medication (topical/oral antifungal)?
• Is oral treatment necessary? If so, what is the expected treatment duration?
• Are additional tests, such as liver function tests, needed? What is the testing schedule?
• What lifestyle changes should I make to prevent recurrence?
• What precautions should I take when using shared spaces (showers, swimming pools)?

Examples of Condition-Specific Questions

• For tinea pedis (athlete’s foot)
  • How should I manage my shoes and socks to reduce recurrence? (e.g., disinfection methods and whether powder use is recommended)
  • Until when should I avoid exercising, swimming, or using shared showers?
• For tinea unguium (fungal infection of the fingernails/toenails)
  • How long is it expected to take for normal fingernails/toenails to grow out completely after treatment?
  • How should elevated liver enzyme levels be managed while taking oral antifungals? (including testing intervals and criteria for stopping the medication)

Additional Cautions

• Using steroid ointment alone on the skin or nails may alter the lesions and make diagnosis difficult (‘tinea incognito’); therefore, confirm the diagnosis before using steroids.
• If a fungal infection is suspected, accurate diagnosis (microscopy/culture) is recommended to select an appropriate antifungal and determine the treatment duration.