What is the recommended treatment for onychomycosis (toenail fungus)?

Treatment of Toenail Fungus (Onychomycosis)

Oral terbinafine 250mg once daily for 12 weeks is the most effective first-line treatment for toenail fungus (onychomycosis), with mycological cure rates of 70-80%. 1

Diagnosis Confirmation

Before initiating treatment:

• Confirm diagnosis through:
  • Potassium hydroxide (KOH) preparation
  • Fungal culture
  • Nail biopsy in doubtful cases 1, 2
• Important: Only about half of nail dystrophies are actually caused by fungi 1

Treatment Options

First-Line Therapy

1. Oral Terbinafine

   • Dosage: 250mg once daily 2
   • Duration: 12 weeks for toenails, 6 weeks for fingernails 2
   • Efficacy: 70-80% for toenail infections 1
   • Mechanism: Fungicidal activity against dermatophytes 3
   • Note: Optimal clinical effect is seen some months after mycological cure due to time required for healthy nail outgrowth 2

2. Oral Itraconazole

   • Dosage: 200mg daily 1
   • Duration: 12 weeks 1
   • Efficacy: 45.8% mycological cure rate at 48 weeks 1
   • Particularly effective for Candida onychomycosis (92% cure rate with pulse therapy) 1
   • Take with food for optimal absorption 1
   • Contraindicated in heart failure 1

Alternative Oral Therapies

• Fluconazole: 150-450mg once weekly for at least 6 months; useful when terbinafine or itraconazole cannot be tolerated 1
• Griseofulvin: 500-1000mg daily for 12-18 months; lower efficacy and higher relapse rates compared to terbinafine and itraconazole 1

Topical Treatments

For patients unable to tolerate oral therapy or with contraindications:

1. Ciclopirox 8% nail lacquer

   • Apply as part of a comprehensive management program 4
   • Requires removal of unattached, infected nails as frequently as monthly by a healthcare professional 4
   • Mycological cure rates of 34% 1

2. Other effective topical options:

   • Amorolfine 5% nail lacquer (50% efficacy in distal nail infections) 1
   • Efinaconazole 10% solution (50% mycological cure rates) 1
   • Tioconazole 28% solution (contraindicated in pregnancy) 1

Special Populations

• Diabetic patients: Terbinafine preferred due to lower risk of drug interactions 1
• Immunosuppressed patients: Consider topical options when systemic therapy is contraindicated 1
• HIV patients: Terbinafine and fluconazole preferred due to lower risk of interactions with antiretrovirals 1

Monitoring and Safety

• Before starting terbinafine:

  • Perform liver function tests 2
  • Not recommended for patients with chronic or active liver disease 2

• During treatment:

  • Monitor for hepatotoxicity (nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice) 2
  • Watch for taste/smell disturbances which may be prolonged or permanent 2
  • Be alert for depressive symptoms 2

Prevention of Reinfection

• Keep nails short and clean
• Dry feet thoroughly after bathing
• Wear cotton, absorbent socks and change daily
• Apply antifungal powders to shoes and feet
• Avoid sharing nail clippers
• Wear protective footwear in public areas
• Treat concomitant fungal infections promptly 1

Treatment Failure Management

Common reasons for failure:

• Poor compliance
• Poor absorption
• Immunosuppression
• Dermatophyte resistance
• Subungual dermatophytoma
• Zero nail growth 1

Options for managing treatment failure:

• Partial nail removal plus antifungal therapy
• Alternative antifungal drug
• Complete nail avulsion combined with antifungal therapy 1

Common Pitfalls to Avoid

• Not confirming diagnosis before initiating treatment
• Inadequate treatment duration
• Simultaneous use of corticosteroids with antifungals
• Unrealistic expectations about improvement speed
• Not addressing predisposing factors
• Not implementing preventive measures 1

Recent research from 2023 confirms that continuous dosing of terbinafine (250mg daily for 12 weeks) is significantly more effective than pulse dosing, with a clinical cure rate of 76.67% compared to 26.67% for pulse therapy 5.