What is a good antibiotic (abc) to give an adult patient for an abscessed tooth?

Antibiotic Selection for Abscessed Tooth

For an adult with a dental abscess, amoxicillin 500-875 mg orally three times daily for 5 days is the first-line antibiotic choice, but only after surgical drainage (incision and drainage, root canal, or extraction) has been performed or planned. 1, 2

Primary Treatment Principle

Surgical intervention is the cornerstone of treatment and must not be delayed. Antibiotics alone are inadequate without proper source control. 1, 2

• Root canal therapy or tooth extraction is the definitive treatment for acute dental abscesses 1
• Incision and drainage is required for dentoalveolar abscesses with accessible pus 1
• Multiple systematic reviews demonstrate no significant difference in pain or swelling when antibiotics are added to proper surgical treatment in localized abscesses without systemic signs 1

When to Add Antibiotics

Antibiotics are indicated only in specific clinical scenarios:

• Systemic involvement present: fever, tachycardia, tachypnea, malaise, or elevated white blood cell count 1, 2
• Spreading infection: cellulitis, diffuse swelling beyond the localized area, or facial space involvement 1, 2
• Immunocompromised patients: medically compromised or immunosuppressed status 1, 2
• Progressive infection: requiring referral to oral surgery or hospitalization 1

First-Line Antibiotic Regimen

Amoxicillin is the preferred first-line agent:

• Dosing: 500-875 mg orally three times daily 2
• Duration: 5 days for immunocompetent patients with adequate source control 1, 2
• Alternative penicillin option: Phenoxymethylpenicillin (Penicillin V) 1, 2
• Evidence base: High bacterial susceptibility (76.6%) demonstrated in clinical studies of early-stage dentoalveolar abscess 3

Penicillin Allergy Alternative

For documented penicillin allergy, clindamycin is the preferred alternative:

• Dosing: 300-450 mg orally three times daily 1, 2
• Duration: 5 days 1
• Advantage: Excellent anaerobic coverage for typical dental abscess pathogens 2

Second-Line Options for Treatment Failure

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

• Amoxicillin-clavulanate (Augmentin): 875/125 mg twice daily 1
  • Provides coverage against beta-lactamase producing organisms 1
  • Consider in patients with antibiotic use within the past month, moderate-to-severe symptoms, or age >65 years 1
• Amoxicillin plus metronidazole combination 1, 4
  • Enhanced anaerobic coverage for refractory infections 4

Inpatient Management

For hospitalized patients with severe systemic involvement:

• IV clindamycin: 600-900 mg IV every 6-8 hours (preferred for penicillin allergy) 1
• Broader coverage options for deep tissue involvement:
  • Piperacillin-tazobactam 3.375g IV every 6 hours or 4.5g IV every 8 hours 1
  • Ceftriaxone 1g IV every 24 hours plus metronidazole 500mg IV every 8 hours 1
• Maximum duration: 7 days for immunocompromised or critically ill patients with adequate source control 1, 2

Common Pitfalls to Avoid

• Do not prescribe antibiotics without surgical intervention - this delays definitive treatment and promotes resistance 1, 2
• Do not use fluoroquinolones - inadequate coverage for typical dental abscess pathogens 1
• Do not routinely cover for MRSA - not supported by current evidence for dental abscesses 1
• Do not exceed 7 days of treatment - longer courses are unnecessary with proper source control 1, 2

Treatment Algorithm

1. Assess for systemic involvement or spreading infection:

   • If absent → Surgical drainage only, no antibiotics 1
   • If present → Proceed to step 2 1, 2

2. Perform or arrange immediate surgical intervention (extraction, root canal, or incision/drainage) 1, 2

3. Select antibiotic based on allergy status:

   • No penicillin allergy → Amoxicillin 500-875 mg TID for 5 days 2
   • Penicillin allergy → Clindamycin 300-450 mg TID for 5 days 1, 2

4. Reassess at 48-72 hours:

   • Improving → Complete 5-day course 1, 2
   • Not improving → Switch to amoxicillin-clavulanate or add metronidazole 1, 4