Is Keflex (cephalexin) an appropriate initial treatment for an otherwise healthy adult or adolescent with an ingrown toenail?

Keflex for Ingrown Toenail

Yes, cephalexin (Keflex) is the recommended first-line antibiotic for infected ingrown toenails in otherwise healthy adults and adolescents. 1

When Antibiotics Are Actually Indicated

Before prescribing any antibiotic, confirm true infection is present by looking for:

• Purulent drainage 1
• Significant erythema or cellulitis extending beyond the nail fold 1
• Pus or abscess formation 1

Important caveat: Many ingrown toenails present with inflammation alone and do not require antibiotics—only those with clear signs of bacterial infection warrant antimicrobial therapy. 2, 3

Antibiotic Selection Algorithm

First-Line Treatment

• Cephalexin (Keflex) provides appropriate coverage for Staphylococcus aureus, the most common pathogen in infected ingrown toenails 1
• Standard adult dosing: 500 mg orally every 12 hours for 10 days 4

If Treatment Fails or MRSA Suspected

• Switch to sulfamethoxazole-trimethoprim (Bactrim) for broader coverage including methicillin-resistant Staphylococcus aureus 1

Alternative for Mild-Moderate Cases with Paronychia

• Amoxicillin-clavulanate (Augmentin) 500 mg/125 mg every 12 hours can be used when paronychia accompanies the ingrown toenail 1

For Penicillin-Allergic Patients

• Cephalexin should be avoided in patients with immediate hypersensitivity to penicillin 4
• Consider clindamycin 300 mg three times daily for 10 days as an alternative 4

Essential Adjunctive Measures (Not Optional)

Antibiotics alone are insufficient. Concurrent local care is mandatory:

• Warm antiseptic soaks with dilute vinegar (50:50 dilution with water) or 2% povidone-iodine for 10-15 minutes twice daily 1, 2
• Apply mid- to high-potency topical corticosteroid to reduce inflammation 5, 2
• Consider gutter splinting to separate the ingrown nail edge from the lateral fold for immediate pain relief 2

Critical Pitfalls to Avoid

Culture Before Antibiotics in Severe Cases

• Obtain bacterial cultures before starting antibiotics in severe infections or treatment failures to guide appropriate antibiotic selection 1

Watch for Fungal Superinfection

• Up to 25% of ingrown toenail cases develop secondary fungal superinfections 1
• If the patient fails to respond to initial antibiotic therapy, obtain fungal cultures and consider antifungal treatment 1

Special Population: Diabetic Patients

• Diabetic patients with ingrown toenails require immediate treatment by a trained healthcare professional due to high risk of progression to foot ulceration 1, 6
• These patients need more aggressive management and closer follow-up (every 1-3 months) 6

Definitive Management Considerations

While antibiotics treat infection, they do not address the underlying mechanical problem:

• Surgical approaches (partial nail avulsion with phenolization) are superior to nonsurgical treatment for preventing recurrence 2, 3
• Consider referral for definitive surgical management in recurrent cases after the acute infection resolves 2, 7