What amoxicillin strength and dosing frequency should be given to treat a dental infection in an adult, and what are the corresponding pediatric weight‑based regimen, alternative for penicillin allergy, and dose adjustment for renal impairment?

Amoxicillin for Dental Caries (Dental Abscess)

For adults with a dental abscess, prescribe amoxicillin 500 mg orally three times daily for 5 days, but only after ensuring surgical drainage (incision and drainage, root canal, or extraction) has been performed or arranged, and only if systemic signs of infection are present. 1

Critical First Principle: Surgery Is Primary Treatment

• Antibiotics alone are inadequate for dental abscesses—surgical intervention (drainage, root canal therapy, or extraction) is the cornerstone of treatment and must not be delayed. 1
• Antibiotics serve only as adjuncts to definitive surgical management, not as standalone therapy. 1

When to Add Antibiotics to Surgical Treatment

Add systemic antibiotics only when:

• Systemic involvement is present: fever, tachycardia, tachypnea, or elevated white blood cell count. 1
• Spreading infection beyond the tooth: cellulitis, diffuse facial swelling, or rapidly progressing infection. 1
• Immunocompromised or medically compromised patients: diabetes, chronic cardiac/hepatic/renal disease, or age >65 years. 1
• Extension into cervicofacial soft tissues requiring more aggressive management. 1

Do NOT prescribe antibiotics when:

• Localized abscess without systemic symptoms and adequate surgical drainage can be achieved. 1
• Irreversible pulpitis alone (no abscess). 1
• Acute apical periodontitis without systemic involvement. 1

Adult Dosing Regimen

First-line oral therapy:

• Amoxicillin 500 mg orally three times daily for 5 days (or 875 mg twice daily). 1
• Alternative: Penicillin V (phenoxymethylpenicillin) 500 mg four times daily for 5–7 days. 1, 2, 3

For penicillin allergy:

• Clindamycin 300–450 mg orally three times daily for 5–7 days. 1
• Pediatric clindamycin dosing: 10–20 mg/kg/day divided into 3 doses. 1

For recent antibiotic use (within past month):

• Amoxicillin-clavulanate 875 mg/125 mg twice daily instead of plain amoxicillin, due to increased risk of beta-lactamase-producing organisms. 1
• High-dose option for severe infections: 2 g amoxicillin component twice daily. 1

Pediatric Weight-Based Dosing

Standard-dose amoxicillin:

• 25–50 mg/kg/day divided into 3–4 doses for children without recent antibiotic exposure or severe illness. 4, 1

High-dose amoxicillin (for severe infections or high-resistance areas):

• 80–90 mg/kg/day divided twice daily (approximately 360–400 mg twice daily). 4
• Indications for high-dose: age <2 years, daycare attendance, recent antibiotic use within 30 days, moderate-to-severe illness, or communities with >10% penicillin-nonsusceptible Streptococcus pneumoniae. 4

Pediatric amoxicillin-clavulanate:

• 90 mg/kg/day (amoxicillin component) with 6.4 mg/kg clavulanate divided twice daily, not exceeding 2 g every 12 hours. 4, 1

Severe Infections Requiring IV Therapy

Indications for hospitalization and IV antibiotics:

• Risk of airway compromise from infection. 1
• Systemic toxicity with fever and altered mental status. 1
• Deep tissue involvement or inability to take oral medications. 1

IV regimens:

• Ampicillin-sulbactam 1.5–3.0 g IV every 6 hours (preferred single-agent therapy). 1
• Alternative: Ceftriaxone 1 g IV every 24 hours plus metronidazole 500 mg IV every 8 hours. 1
• For penicillin allergy: Clindamycin 600–900 mg IV every 6–8 hours. 1
• Pediatric clindamycin IV: 10–13 mg/kg/dose every 6–8 hours (maximum 40 mg/kg/day). 1

For immunocompromised patients or severe infections:

• Consider broader coverage with piperacillin-tazobactam 3.375 g IV every 6 hours or 4.5 g IV every 8 hours. 1

Renal Dose Adjustments for Amoxicillin-Clavulanate

• CrCl 10–30 mL/min: Amoxicillin-clavulanate 875 mg/125 mg once daily (or 500 mg/125 mg every 12 hours). 1
• CrCl <10 mL/min: Amoxicillin-clavulanate 875 mg/125 mg once daily. 1
• Hemodialysis: Administer dose after each dialysis session. 1

Duration of Therapy

• 5–7 days for uncomplicated dental abscesses with adequate surgical source control (moderate-quality evidence). 1, 5
• Maximum 7 days in most cases with adequate source control; extending beyond this does not improve outcomes. 1
• One small RCT found a 3-day course of amoxicillin clinically non-inferior to 7 days for odontogenic infection requiring extraction, though all participants started antibiotics 2 days before extraction (not typical practice). 5

Treatment Failures or Second-Line Options

If no improvement within 2–3 days on first-line therapy:

• Switch to amoxicillin-clavulanate 875 mg/125 mg twice daily. 6
• Alternative: Clindamycin 300–450 mg three times daily. 1
• Consider adding metronidazole to amoxicillin (not as monotherapy). 1, 6

For patients allergic to both penicillin and clindamycin:

• Doxycycline 100 mg orally twice daily for 5–7 days (contraindicated in children <8 years and pregnant women). 1
• Alternative: Trimethoprim-sulfamethoxazole 1–2 double-strength tablets (160/800 mg) twice daily for 5–7 days. 1
• Pediatric azithromycin: 10 mg/kg once daily for 3–5 days (maximum 500 mg/day). 1

Common Pitfalls to Avoid

• Never prescribe antibiotics without arranging definitive surgical treatment—multiple systematic reviews show no significant benefit of antibiotics alone for pain or swelling outcomes. 1
• Do not extend antibiotic duration beyond 7 days without clear indication; longer courses do not improve outcomes with adequate source control. 1
• Avoid plain amoxicillin if the patient used any beta-lactam within the past month—switch to amoxicillin-clavulanate to cover beta-lactamase producers. 1
• Do not use metronidazole as monotherapy for dental abscesses—it lacks adequate coverage of facultative and anaerobic gram-positive cocci. 2, 3
• Reassess within 48–72 hours—if no improvement, consider inadequate drainage or deeper infection requiring imaging. 1
• If abscess has not reduced in size within 4 weeks after initial drainage, repeat surgical drainage is almost always required. 1

Bacteriology Context

• Dental abscesses are typically polymicrobial, involving both aerobic and anaerobic organisms including Streptococcus, Peptostreptococcus, Peptococcus, Fusobacterium, Bacteroides, and Actinomyces species. 1, 2
• Penicillin V and amoxicillin remain highly effective, with 96% of bacterial strains from dental abscesses sensitive or moderately sensitive, and MIC of penicillin between 0.03–2 mg/L for the vast majority. 7