What is the best antibiotic for a fingernail (onychial) infection?

Best Antibiotic for Fingernail Infection

For fungal fingernail infections (onychomycosis), terbinafine is the first-line treatment, while for bacterial fingernail infections (paronychia), flucloxacillin or dicloxacillin are recommended as first-line therapy. 1, 2

Determining the Type of Infection

Before selecting an antibiotic, it's crucial to determine whether the infection is fungal or bacterial:

• Fungal infection (onychomycosis): Characterized by nail discoloration, thickening, brittleness, and separation from the nail bed 1
• Bacterial infection (paronychia): Characterized by redness, swelling, pain around the nail fold, and possibly pus formation 2
• Confirmation: Mycological testing (microscopy and culture) should be performed before initiating treatment 1

Treatment for Fungal Fingernail Infections

Systemic Therapy (Preferred for Most Cases)

• First-line: Terbinafine 250 mg daily for 6 weeks 1

  • Highest cure rates (80-90% for fingernail infections) 1
  • Fungicidal action provides superior efficacy against dermatophytes 1
  • Monitor baseline liver function tests and complete blood count in patients with history of hepatotoxicity 1

• Second-line: Itraconazole 1

  • Option 1: 200 mg daily for 12 weeks continuously 1
  • Option 2: Pulse therapy - 400 mg daily for 1 week per month, for 2 months (fingernails) 1
  • Preferred for Candida infections 1
  • Take with food for optimal absorption 1

• Alternative: Fluconazole 150-450 mg weekly for 3 months 1

  • Consider when terbinafine or itraconazole cannot be tolerated 1
  • Less effective than terbinafine or itraconazole but better compliance with once-weekly dosing 1

Topical Therapy (Limited Cases)

Only recommended for:

• Very early or superficial infections 1
• When systemic therapy is contraindicated 1
• As adjunct to systemic therapy 1

Options include:

• Amorolfine 5% lacquer: Applied once or twice weekly for 6-12 months 1
• Ciclopirox 8% lacquer: Applied once daily for up to 48 weeks 1
• Tioconazole 28% solution: Applied twice daily for 6-12 months 1

Treatment for Bacterial Fingernail Infections

• For Staphylococcus aureus (most common): 3

  • First-line: Flucloxacillin or dicloxacillin 3
  • Alternatives: Cephalexin 250-500 mg four times daily for 7-10 days 4, 5

• For Pseudomonas aeruginosa (recognizable by green or black nail discoloration):

  • Ciprofloxacin is the treatment of choice 2

• For mixed bacterial infections:

  • Topical antiseptics (octenidine) may be used alongside antibiotics 2
  • Topical antibiotics like nadifloxacin or gentamicin for mild cases 2

Special Considerations

For Candida Infections of the Nail

• Itraconazole is most effective for Candida onychomycosis with nail plate invasion 1
  • Use 400 mg daily for 1 week per month, repeated for 2 months 1

For Children

• Itraconazole: 5 mg/kg/day for 1 week per month, for 2 months (fingernails) 1
• Terbinafine: Dosed by weight - 62.5 mg for <20 kg, 125 mg for 20-40 kg, 250 mg for >40 kg; for 6 weeks 1

Prevention of Recurrence

• Keep nails short and clean 1
• Avoid sharing nail clippers 1
• Apply antifungal powders to shoes if fungal infection 1
• Treat all infected family members simultaneously 1

Common Pitfalls to Avoid

• Treating without confirmation: Always confirm diagnosis with mycological testing before starting treatment 1
• Inadequate duration: Shorter treatment courses lead to higher relapse rates 1
• Ignoring underlying conditions: Diabetes and immunosuppression can affect treatment response 1
• Expecting immediate results: Complete nail regrowth takes time even after the infection is cleared 1