Treatment of Fungal Infections

Diagnosis and Confirmation

• The diagnosis of onychomycosis should be confirmed through microscopic examination with potassium hydroxide (KOH), mycological culture, or nail biopsy in doubtful cases, as only approximately half of nail dystrophies are caused by fungi, as recommended by the British Journal of Dermatology guidelines 1, 2

Treatment Options

• Effective topical treatments for onychomycosis include:

• Oral antifungal medications:

  Medication	Dosage	Duration	Efficacy
  Terbinafine	250mg once daily	12 weeks	73-94% mycological cure rate (high-quality evidence) [3]
  Itraconazole	200mg daily	12 weeks	45.8% mycological cure rate at 48 weeks (moderate-quality evidence) [3]
  Fluconazole	150-450mg once weekly	at least 6 months	useful alternative when patients cannot tolerate terbinafine or itraconazole (low-quality evidence) [3]
  Griseofulvin	500-1000mg daily	12-18 months	lower efficacy and higher relapse rates compared to terbinafine and itraconazole (moderate-quality evidence) [3]

• Terbinafine is generally preferred over itraconazole for dermatophyte infections, with a strength of recommendation of A, and has an efficacy of 70-80% for toenail infections and 80-90% for fingernail infections 3, 1
• Itraconazole is recommended as a first-line treatment for dermatophyte onychomycosis, with a strength of recommendation of A, and is particularly effective for Candida onychomycosis (92% cure rate with pulse therapy) 3
• Fluconazole is a useful alternative when patients cannot tolerate terbinafine or itraconazole, with a strength of recommendation of B 3
• Griseofulvin has a lower efficacy and higher relapse rates compared to terbinafine and itraconazole, with a strength of recommendation of C 3

Special Populations

• Pediatric dosing of terbinafine varies by weight, with 62.5mg daily for <20kg, 125mg daily for 20-40kg, and 250mg daily for >40kg, as recommended by the British National Formulary 2
• In patients with HIV, terbinafine and fluconazole are preferred due to their lower risk of interactions with antiretrovirals, with a strength of evidence rated as moderate 3
• Diabetic patients: terbinafine is preferred due to lower risk of drug interactions, and topical treatments are appropriate for mild-to-moderate infections where risk of drug interaction is high, as suggested by the American Diabetes Association 3
• Immunosuppressed patients: consider topical options when systemic therapy is contraindicated, and terbinafine or fluconazole is preferred over itraconazole due to fewer interactions with antiretrovirals, as reported by the Infectious Diseases Society of America 3

Prevention and Management of Treatment Failure

• Good hygiene practices, such as keeping feet dry, wearing cotton and absorbent socks, and changing them daily, can help prevent reinfection, as well as wearing protective footwear in public areas and considering discarding heavily contaminated footwear or treating with antifungal sprays 4
• The British Journal of Dermatology recommends keeping nails short and clean, drying feet thoroughly after bathing, wearing cotton, absorbent socks and changing daily, applying antifungal powders to shoes and feet, avoiding sharing nail clippers, wearing protective footwear in public areas, and treating concomitant fungal infections promptly to prevent recurrences, which occur in 40-70% of cases 3
• Reasons for treatment failure include poor compliance, poor absorption, immunosuppression, dermatophyte resistance, subungual dermatophytoma, and zero nail growth, emphasizing the need for careful patient evaluation and management, as reported by the British Journal of Dermatology 1
• Management of treatment failure includes options such as partial nail removal plus antifungal therapy, alternative antifungal drug, or complete nail avulsion combined with antifungal therapy, as suggested by the British Journal of Dermatology 1
• Common pitfalls to avoid include not confirming the diagnosis before initiating treatment, inadequate treatment duration, simultaneous use of corticosteroids with antifungals, having unrealistic expectations about the speed of improvement, not addressing predisposing factors, and not implementing preventive measures to avoid reinfections 3