What is the recommended treatment for a patient with an infected fingernail?

Treatment for Infected Fingernail

For a bacterial fingernail infection (acute paronychia), initiate warm soaks with or without antiseptics, drain any abscess present, and use oral antibiotics targeting Staphylococcus aureus such as cephalexin or amoxicillin-clavulanate if infection is moderate to severe. 1, 2

Distinguishing the Type of Infection

The first critical step is determining whether the infection is bacterial or fungal, as treatment differs substantially:

• Bacterial infections (acute paronychia) present with acute onset pain, erythema, warmth, purulent discharge, and potential abscess formation around the nail fold 1, 2
• Fungal infections (onychomycosis) typically show gradual nail discoloration, thickening, minimal pain, and chronic progression over weeks to months 1, 3

Obtain bacterial cultures if pus is present to guide antibiotic selection, particularly in severe or non-responding cases 4, 1

Treatment Algorithm for Bacterial Nail Infections

Mild Infections (No Abscess)

• Warm soaks with or without Burow solution or 1% acetic acid, applied 3-4 times daily 2
• Topical antiseptics such as octenidine can be applied 3
• Topical antibiotics with or without topical steroids if simple soaks do not relieve inflammation within 48 hours 2

Moderate to Severe Infections (With or Without Abscess)

• Mandatory drainage if abscess is present—this can range from needle aspiration to incision with a scalpel 4, 2, 5
• Oral antibiotics are indicated if adequate drainage cannot be achieved, infection is severe, or patient is immunocompromised 2, 5
  • First-line choice: Cephalexin (first-generation cephalosporin) for coverage against Staphylococcus aureus and Streptococcus pyogenes 1
  • Alternative options: Amoxicillin-clavulanate, clindamycin, or doxycycline 4
  • For pediatric patients with oral habits: Consider amoxicillin-clavulanate or clindamycin for mixed anaerobic/aerobic coverage 5

Special Pathogen Considerations

• Pseudomonas aeruginosa (green or black nail discoloration): Treat with ciprofloxacin 3
• Methicillin-resistant Staphylococcus aureus (MRSA): Consider clindamycin or doxycycline based on local resistance patterns 5

Treatment for Fungal Nail Infections (Onychomycosis)

If the infection is determined to be fungal rather than bacterial:

First-Line Systemic Therapy

Terbinafine is the preferred first-line treatment for dermatophyte onychomycosis and is generally superior to itraconazole 6, 1:

• Dosing: 250 mg daily for 6 weeks for fingernails and 12-16 weeks for toenails 6, 7
• Baseline monitoring: Obtain liver function tests and complete blood count before initiating therapy 6, 1
• Efficacy: Achieves mycological cure in 79% of fingernail infections 7

Alternative Systemic Options

• Itraconazole pulse therapy: 400 mg daily for 1 week per month; 2 pulses for fingernails, 3 pulses for toenails 6, 1
• Fluconazole: 150-450 mg weekly for 3 months for fingernails if terbinafine or itraconazole are contraindicated or not tolerated 6, 1

Topical Therapy

• Amorolfine 5% lacquer applied once or twice weekly for 6-12 months for superficial or distal infections 6
• Ciclopirox 8% lacquer applied daily for up to 48 weeks when systemic therapy is contraindicated 6

Adjunctive Measures for Fungal Infections

• Mechanically remove dermatophytomas (fungal masses), as these resist antifungal treatment alone 1
• Keep nails as short as possible and avoid sharing nail clippers 6, 1
• Apply topical emollients daily to periungual folds, matrix, and nail plate 1

Chronic Paronychia Management

For chronic paronychia (symptoms ≥6 weeks), which represents an irritant dermatitis rather than acute infection 2:

• Identify and eliminate irritant exposure (chemicals, excessive moisture) 2
• Topical steroids or calcineurin inhibitors to treat inflammation 2
• Combination topical therapy with insulating polymers, antifungals (octopirox, climbazole), and anti-inflammatory agents may be effective 8
• Add oral fluconazole 100 mg for 20 days if Candida species are proven on culture 8

Critical Pitfalls to Avoid

• Do not start antibiotics for clean puncture wounds without signs of infection—prophylactic antibiotics are not routinely indicated 4
• Do not treat fungal infections with antibiotics—this is ineffective and delays appropriate antifungal therapy 1, 3
• Do not skip drainage if abscess is present—antibiotics alone without drainage will fail 4, 2
• Do not forget baseline liver function tests before starting systemic antifungals, particularly terbinafine or itraconazole 6, 1

Follow-Up and Monitoring

• Reassess after 2 weeks to determine if infection has improved with oral antibiotics and local care 4, 1
• If infection worsens or does not improve: Consider alternative antibiotics based on culture results or surgical intervention 1
• For fungal infections: Optimal clinical effect occurs months after treatment completion due to time required for healthy nail outgrowth 7
• Monitor for nail avulsion needs: If subungual hematoma or abscess develops, partial or total nail avulsion may be required 4, 1