What antibiotics are recommended for treating an infected pilonidal cyst?

Antibiotics for Pilonidal Cyst

Primary Recommendation

For an infected pilonidal cyst, incision and drainage is the primary treatment, with antibiotics reserved as adjunctive therapy only when systemic signs of infection are present (fever >38°C, tachycardia >90 bpm, or extensive surrounding cellulitis >5 cm from wound edge). 1

When to Add Antibiotics

Antibiotics should be added to surgical drainage when any of the following are present:

• Systemic inflammatory response syndrome (SIRS) including fever, tachycardia, tachypnea, or abnormal white blood cell count 1
• Erythema and induration extending >5 cm from the wound edge 2
• Immunocompromised status 1, 2
• Signs of systemic toxicity 2

For simple pilonidal abscesses without these features, antibiotics are not routinely indicated after adequate drainage. 1

Recommended Antibiotic Regimens

First-Line Option

Amoxicillin-clavulanate is the preferred empiric choice, providing broad-spectrum coverage against the polymicrobial flora (aerobic coliforms and anaerobes) typically found in pilonidal infections. 2, 3, 4

• This regimen has demonstrated success in treating actinomycosis associated with pilonidal abscesses 3, 4
• Duration: 7-10 days 5, 6

Alternative Regimens (for penicillin allergy or treatment failure)

Combination therapy with dual anaerobic coverage:

• Ciprofloxacin plus metronidazole 1, 2
• Ceftriaxone plus metronidazole 1, 2

Alternative monotherapy:

• Cefalexin plus metronidazole (used successfully in clinical studies) 5

Clinical Algorithm

1. Perform incision and drainage as primary treatment 1
2. Assess for systemic signs: Check temperature, heart rate, extent of surrounding erythema 1, 2
3. If systemic signs present: Start amoxicillin-clavulanate for 7-10 days 2, 5
4. If no systemic signs: Drainage alone is sufficient; no antibiotics needed 1
5. For recurrent abscesses: Culture the abscess, treat with antibiotics active against isolated pathogen for 5-10 days 1

Important Caveats

• Antibiotics do not replace surgical drainage - they are adjunctive only and reduce morbidity when systemic signs are present 2
• Aspiration with antibiotics may be considered in selected patients (non-immunocompromised, no diabetes, no overlying skin necrosis), showing 83% success rates with cefalexin plus metronidazole 5
• For recurrent disease: Consider local factors such as retained foreign material or inadequate initial drainage before attributing failure to antibiotic choice 1
• Actinomyces involvement (though uncommon) responds well to amoxicillin-clavulanate and may require prolonged therapy 3, 4