What is the treatment for onychomycosis (fungal infection of the nails)?

Treatment of Fungal Nail Infections (Onychomycosis)

For dermatophyte nail infections, start oral terbinafine 250 mg daily for 12 weeks for toenails or 6 weeks for fingernails after confirming the diagnosis with mycological testing. 1, 2

Diagnostic Confirmation Required Before Treatment

• Never begin treatment without mycological confirmation through KOH preparation, fungal culture, or nail biopsy 1, 3, 2
• Treatment failure is common when diagnosis is made on clinical grounds alone 4
• Identifying the causative organism is crucial because treatment varies by pathogen type 3

First-Line Treatment Algorithm

For Dermatophyte Infections (90-95% of cases)

Terbinafine is superior to all other antifungals both in vitro and in vivo and should be considered first-line treatment 1, 3

• Terbinafine 250 mg once daily:
  • Fingernails: 6 weeks 1, 2
  • Toenails: 12 weeks 1, 2
• Expected cure rates: 70-80% for toenails, 80-90% for fingernails 1, 3
• Can be taken with or without food 2

For Candida/Yeast Infections

Itraconazole is the most effective agent when the nail plate is invaded by Candida 1

• Itraconazole 400 mg daily for 1 week per month (pulse therapy):
  • Fingernails: 2 pulses 1
  • Toenails: 3-4 pulses 1, 3
• Must be taken with food and acidic pH for optimal absorption 1
• Alternative: Fluconazole 150-450 mg weekly for at least 6 months 3, 5

Monitoring and Safety

For Terbinafine:

• Baseline liver function tests (ALT/AST) and complete blood count advised for all patients before starting 1, 2
• Monitor for liver problems: persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, or pale stools 2
• Common adverse effects: headache, taste disturbance (may be permanent), gastrointestinal upset 3, 2
• Discontinue immediately if taste/smell disturbance, depressive symptoms, or serious skin reactions occur 2

For Itraconazole:

• Monitor hepatic function in patients with pre-existing liver issues or those receiving continuous therapy for more than a month 1, 3
• Contraindicated in heart failure 1
• Common adverse effects: headache, gastrointestinal upset 3

Important Clinical Caveats

Treatment Expectations:

• Complete nail regrowth takes up to 18 months due to slow toenail growth 1, 3
• Optimal clinical effect is seen months after mycological cure and cessation of treatment 2
• Nail appearance may not return to completely normal if pre-existing dystrophy was present 3

Treatment Failure (20-30% of cases):

Common causes include:

• Poor compliance 1, 3
• Poor drug absorption 3
• Immunosuppression 3
• Dermatophyte resistance 3
• Presence of dermatophytoma (dense white lesion beneath nail) 1, 3
• Nail thickness >2 mm, severe onycholysis 1

For dermatophytomas or treatment-resistant cases, nail removal combined with oral therapy achieves cure rates close to 100% 3

Prevention of Recurrence

Recurrence rates are high (40-70%) without preventive measures 1

• Keep nails as short as possible 1, 3
• Always wear protective footwear in public bathing facilities, gyms, and hotel rooms 1
• Apply antifungal powders (miconazole, clotrimazole, or tolnaftate) to shoes and feet 1
• Wear cotton, absorbent socks 1, 3
• Discard heavily contaminated "old and mouldy" footwear, or treat shoes by placing naphthalene mothballs in a tightly tied plastic bag for minimum 3 days 1
• Alternatively, spray terbinafine solution into shoes periodically 1
• Treat all infected family members simultaneously 1, 3
• Avoid sharing toenail clippers 1

Topical Therapy (Limited Role)

• Topical treatment is inferior to systemic therapy except for very distal infection or superficial white onychomycosis 1
• Topical agents (amorolfine, ciclopirox) may be considered when <50% of nail plate is affected and fewer than 3 nails are involved 6