What are the recommended antibiotics for bacterial tonsillitis?

Recommended Antibiotics for Bacterial Tonsillitis

For suspected or proven bacterial tonsillitis, amoxicillin or penicillin V should be the first-line antibiotic treatment, with cephalexin as the preferred second-line option and clarithromycin reserved only for patients with severe penicillin allergy. 1

First-Line Treatment Strategy

Watchful Waiting vs. Immediate Treatment

• Consider watchful waiting with symptom relief as the initial approach rather than immediate antibiotics, particularly in less severe presentations 1
• Antibiotics provide modest benefit (1-2 days of symptom reduction) but must be weighed against side effects, antimicrobial resistance, and costs 1
• Delayed prescribing (more than 48 hours after initial consultation) is a valid strategy with no significant differences in complication rates compared to immediate treatment 1

When Antibiotics Are Indicated

If antibiotic treatment is warranted based on clinical severity or confirmed Group A streptococcal infection:

First-Line Antibiotics:

• Amoxicillin (preferred in younger children due to taste and suspension availability) 1

  • Pediatric dosing: 50 mg/kg once daily (maximum 1,000 mg) for 10 days 1
  • Adult dosing: 250 mg four times daily or 500 mg twice daily for 10 days 1

• Penicillin V (Phenoxymethylpenicillin) 1

  • Pediatric dosing: 250 mg two or three times daily for 10 days 1
  • Adult dosing: 250 mg four times daily or 500 mg twice daily for 10 days 1
  • Remains the gold standard with proven efficacy over five decades and no documented resistance development 1

• Penicillin G benzathine (intramuscular) - single dose option 1

  • <27 kg: 600,000 units
  • ≥27 kg: 1,200,000 units

Second-Line Treatment Options

For Penicillin Allergy (Non-Severe)

Cephalexin is the preferred second-choice antibiotic based on lower relapse rates, good tolerability, and narrow spectrum 1

• Dosing: 20 mg/kg per dose twice daily (maximum 500 mg per dose) for 10 days 1
• Note: Cephalosporins show lower cross-reactivity with penicillin allergy than historically reported (previously overestimated at 10%) 1

For Severe Penicillin Allergy

Clarithromycin should be used when severe penicillin allergy exists 1

• Pediatric dosing: 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days 1
• Critical caveat: Clarithromycin effectiveness is significantly compromised in areas with high macrolide resistance 1, 2
• In regions with common clarithromycin resistance among Group A streptococci, this option may fail to eradicate resistant isolates (14-19% eradication vs. 74-83% for susceptible strains) 2

Alternative for severe allergy:

• Clindamycin: 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days 1

Azithromycin Considerations

While azithromycin is listed as an alternative 1, 3:

• Dosing: 12 mg/kg once daily (maximum 500 mg) for 5 days 1, 3
• Important limitation: Higher risk of late bacteriological recurrence compared to penicillin 1
• Geographic variation in resistance patterns makes this a less reliable choice 1

Key Clinical Pitfalls to Avoid

Duration of Therapy

• 10-day treatment courses are essential for penicillin, amoxicillin, and clarithromycin to prevent rheumatic fever and ensure bacterial eradication 1, 4
• Shorter courses with newer agents may have comparable clinical efficacy but risk inadequate eradication 2

Cephalosporin Superiority Myth

• While meta-analyses show cephalosporins have statistically higher cure rates than penicillin (OR 2.29-2.34), the clinical difference is small and not clinically relevant 1
• The narrow spectrum and proven track record of penicillin outweigh marginal statistical advantages 1

Resistance Considerations

• Routine skin testing for penicillin allergy before first exposure is not necessary 1
• Group A streptococci have shown no resistance to penicillins over five decades 1
• Macrolide resistance is geographically variable and temporally changing—local resistance patterns should guide macrolide use 1, 2

Prevention of Serious Complications

• Antibiotics reduce risk of rheumatic fever (RR 0.27) and suppurative complications including peritonsillar abscess (RR 0.15) and acute otitis media (RR 0.30) 1
• These benefits justify antibiotic use in confirmed or highly suspected bacterial cases despite modest symptomatic improvement

Treatment Failure Management

If first-line antibiotics fail after 48-72 hours, consider ceftriaxone (50 mg IM or IV for 3 days) or clindamycin with or without a third-generation cephalosporin 1