What is the recommended treatment for an adult with a lip infection, covering bacterial, herpes simplex, and candidal etiologies and including alternatives for penicillin allergy?

Treatment of Lip Infections in Adults

Immediate Assessment and Empirical Therapy

For suspected bacterial lip infections, initiate empirical antibiotics covering both Staphylococcus aureus and streptococci, with incision and drainage for any drainable abscess. 1, 2

Initial Clinical Evaluation

Look for these specific features to guide etiology:

• Bacterial infection: Localized swelling, erythema, warmth, purulent drainage, systemic signs (fever, tachycardia), or abscess formation on imaging 1, 2
• Herpes simplex: Grouped vesicles on erythematous base, crusting, history of recurrent episodes in same location, prodromal tingling or burning 3, 4
• Candidal infection: White plaques that scrape off, angular cheilitis (fissuring at mouth corners), concurrent oral thrush 1, 5

Bacterial Lip Infections

First-Line Treatment (Immunocompetent Patients)

Oral regimens (for mild-moderate infection without systemic toxicity):

• Cephalexin 500 mg four times daily for 7-10 days OR
• Dicloxacillin 500 mg four times daily for 7-10 days 1

Penicillin-allergic patients:

• Clindamycin 300-450 mg three times daily for 7-10 days 1
• Doxycycline 100 mg twice daily for 7-10 days 1
• TMP-SMX DS (160/800 mg) twice daily for 7-10 days 1

Severe Infections or MRSA Coverage Required

Intravenous therapy (for systemic toxicity, extensive disease, or immunocompromised hosts):

• Vancomycin 15-20 mg/kg IV every 8-12 hours 1
• Linezolid 600 mg IV/PO twice daily 1
• Daptomycin 4 mg/kg IV daily 1

Continue IV therapy until clinical improvement (typically 48-72 hours), then transition to oral therapy to complete 10-14 days total 2

Surgical Management

Incision and drainage is mandatory for any drainable abscess 1. Obtain culture from purulent material to guide antibiotic selection 1, 2. In immunocompromised patients or those with methicillin-resistant organisms, expect more aggressive disease requiring longer antibiotic courses (≥14 days) 2

Herpes Simplex Lip Infections (Cold Sores)

Episodic Treatment

Initiate therapy within 24 hours of symptom onset for maximum efficacy 3:

• Valacyclovir 2 g orally twice daily for 1 day (doses separated by 12 hours) - most convenient regimen 3
• Famciclovir 1500 mg orally as single dose - equally effective alternative 3
• Acyclovir 400 mg orally five times daily for 5 days - requires more frequent dosing 3

Treatment started during the prodromal phase (tingling, burning) or within the first 24 hours reduces episode duration by approximately 1 day compared to placebo 3. Efficacy drops significantly if treatment begins after lesions fully develop 3

Suppressive Therapy

Consider daily suppressive therapy for patients with ≥6 recurrences per year 3:

• Valacyclovir 500 mg once daily (increase to 1000 mg daily for very frequent recurrences) 3
• Famciclovir 250 mg twice daily 3
• Acyclovir 400 mg twice daily 3

Suppressive therapy reduces recurrence frequency by ≥75% 3. After 1 year of continuous use, discontinue therapy temporarily to reassess recurrence rate, as frequency naturally decreases over time in many patients 3

Severe or Extensive Herpes Infections

For widespread mucocutaneous HSV requiring hospitalization:

• Acyclovir 5-10 mg/kg IV every 8 hours until lesions begin to regress, then switch to oral therapy and continue until complete crusting 3

For immunocompromised patients with extensive disease:

• Use higher oral doses: Acyclovir 400 mg orally three to five times daily 3
• Consider IV therapy earlier due to prolonged episodes and higher dissemination risk 3
• Acyclovir resistance occurs in ~7% of immunocompromised patients versus <0.5% in immunocompetent hosts 3

Acyclovir-Resistant HSV

For confirmed resistance: Foscarnet 40 mg/kg IV every 8 hours until complete lesion resolution 3

Renal Dosing Adjustments

In patients ≥80 years or with renal impairment, assess creatinine clearance before initiating therapy and adjust doses accordingly 3

Candidal Lip Infections

Angular Cheilitis or Oral Candidiasis

First-line topical therapy:

• Nystatin oral suspension 100,000 units swish-and-swallow four times daily for 7-14 days 1, 5
• Miconazole oral gel 5-10 mL applied to affected areas four times daily for 7-14 days 1, 5

Systemic therapy (for extensive or refractory disease):

• Fluconazole 100-200 mg orally once daily for 7-14 days 1

Apply white soft paraffin ointment to lips every 2 hours to protect and moisturize affected areas 5

Adjunctive Supportive Care

For all lip infections with significant inflammation or pain:

• Benzydamine hydrochloride oral rinse/spray every 2-4 hours, especially before meals 5, 6
• Warm saline mouthwashes twice daily to reduce bacterial colonization 5
• Avoid alcohol-containing mouthwashes that cause additional irritation 5
• For severe pain uncontrolled by benzydamine: Viscous lidocaine 2% applied topically 5

Common Pitfalls to Avoid

• Do not rely on topical antivirals alone for herpes labialis - oral therapy is markedly superior 3
• Do not use tetracyclines, sulfonamides, TMP-SMX, or older fluoroquinolones for streptococcal infections - they do not eradicate Group A streptococci 1
• Do not delay incision and drainage when abscess is present - antibiotics alone are insufficient 1
• Do not stop herpes treatment at exactly 7 days if lesions have not fully crusted - continue until complete healing 3
• Do not assume immunocompetence in patients with severe, necrotic, or cavitated lip infections - consider underlying immunosuppression and MRSA 7, 2

Infection Control and Transmission Prevention

Patients with herpes labialis remain contagious until all lesions are fully crusted 3. Advise patients to:

• Avoid direct contact (kissing, sharing utensils/towels) during active lesions 3
• Recognize that asymptomatic viral shedding can occur even on suppressive therapy, though transmission risk is reduced 3
• Apply sunscreen (SPF ≥15) or zinc oxide to lips before UV exposure to prevent recurrences 3, 5