What antibiotic is recommended for a tooth infection?

Antibiotic Treatment for Tooth Infections

Amoxicillin 500 mg three times daily for 5-7 days is the first-line antibiotic for tooth infections, but only after appropriate surgical intervention (drainage, root canal, or extraction) has been performed or is immediately planned. 1, 2

Primary Treatment Principle

Surgical intervention is the cornerstone of treatment and must not be delayed—antibiotics alone are insufficient and serve only as adjunctive therapy. 1, 2 Multiple systematic reviews demonstrate no statistically significant differences in pain or swelling outcomes when antibiotics are added to surgical treatment alone. 2

When Antibiotics Are Actually Indicated

Antibiotics should be prescribed only when specific criteria are met:

• Systemic involvement (fever, malaise, altered mental status) 1, 2
• Spreading infection (cellulitis, diffuse swelling beyond localized area) 1, 2
• Immunocompromised or medically compromised patients 1, 2
• Progressive infections requiring referral to oral surgeons 2
• Inadequate or incomplete surgical drainage 1

First-Line Antibiotic Regimen

For mild to moderate infections with the above indications:

• Amoxicillin 500 mg orally three times daily for 5-7 days 1, 2
• Alternative first-line option: Phenoxymethylpenicillin (Penicillin V) for 5 days 3, 2, 4

The choice of amoxicillin or penicillin V is based on their excellent activity against the typical polymicrobial flora of dental infections (Streptococcus, Peptostreptococcus, Fusobacterium, Bacteroides species). 4, 5

Penicillin-Allergic Patients

For patients with documented penicillin allergy:

• Clindamycin 300-400 mg orally three times daily is the preferred alternative 1, 2
• Pediatric dosing: 10-20 mg/kg/day divided into 3 doses 2

Important distinction for non-anaphylactic reactions: If the patient had only a rash (non-type I hypersensitivity), second- or third-generation cephalosporins (cefdinir, cefuroxime, cefpodoxime) can be safely considered, as the historical 10% cross-reactivity rate is an overestimate from outdated data. 1 However, true anaphylaxis to penicillin is an absolute contraindication to cephalosporins. 1

Treatment Failures or More Severe Infections

If no improvement after 48-72 hours or for moderate-to-severe infections:

• Amoxicillin-clavulanate 875/125 mg orally twice daily 1, 2
• This provides enhanced coverage against beta-lactamase producing organisms and broader anaerobic coverage 2, 6
• Pediatric dosing: 90 mg/kg/day divided twice daily 2

For documented treatment failure after first-line therapy:

• Fluoroquinolone (levofloxacin or moxifloxacin) plus metronidazole 1
• This combination should only be used after confirming adequate surgical drainage has been performed 1

Severe Infections Requiring Hospitalization

For patients with systemic toxicity, rapidly spreading cellulitis, or deep tissue involvement:

• Clindamycin 600-900 mg IV every 6-8 hours (preferred for penicillin-allergic) 2
• Piperacillin-tazobactam 3.375g IV every 6 hours or 4.5g IV every 8 hours 2
• Ceftriaxone 1g IV every 24 hours plus metronidazole 500 mg IV every 8 hours 2
• Consider vancomycin, linezolid, or daptomycin for suspected or confirmed MRSA, though routine MRSA coverage is not recommended for initial empiric therapy 1, 2

Total IV antibiotic duration should be 5-10 days based on clinical response, with a maximum of 7 days in most cases with adequate source control. 2

Critical Pitfalls to Avoid

• Never prescribe antibiotics without ensuring surgical intervention has been performed or is immediately planned—this is the most common reason for treatment failure 1, 2
• Do not use metronidazole alone—it lacks activity against facultative streptococci and aerobic organisms commonly present in dental infections 1, 4
• Avoid prolonged antibiotic courses—5 days is typically sufficient when combined with appropriate surgical management 1, 2
• Do not use fluoroquinolones as monotherapy—they are inadequate for typical dental abscess pathogens 2
• Reassess at 48-72 hours for resolution of fever, marked reduction in swelling, and improved trismus—if not improving, verify surgical drainage was adequate before switching antibiotics 1, 2

Treatment Duration

Maximum antibiotic duration is 7 days for most cases with adequate source control. 2 The evidence does not support longer courses, and prolonged use increases resistance and adverse effects without improving outcomes.