Treatment of Bacterial Tonsillitis
For bacterial tonsillitis, penicillin V or amoxicillin for 10 days remains first-line therapy, with first-generation cephalosporins (cephalexin/cefadroxil) preferred for non-anaphylactic penicillin allergy, and clindamycin for immediate/anaphylactic reactions. 1, 2
Diagnostic Confirmation First
Before prescribing antibiotics, confirm bacterial etiology with rapid antigen detection test (RADT) and/or throat culture for Group A Streptococcus (GAS), as viral tonsillitis requires only supportive care 3. Look for sudden onset sore throat, fever, tonsillar exudates, tender anterior cervical lymphadenopathy, and absence of cough—these features suggest bacterial rather than viral infection 3.
First-Line Treatment (No Penicillin Allergy)
Penicillin V remains the drug of choice due to proven efficacy, narrow spectrum, safety, and low cost, with no documented resistance anywhere in the world 1, 2. The standard regimen is:
- Adults: 500 mg orally every 12 hours or 250 mg every 8 hours for 10 days 1, 4
- Children ≥3 months and <40 kg: 25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours for 10 days 4
Amoxicillin is an acceptable alternative with similar efficacy (86-92% clinical cure rates) and the advantage of better palatability in children 1, 4:
- Adults: 500 mg every 12 hours or 250 mg every 8 hours for 10 days 4
- Children ≥3 months and <40 kg: 25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours for 10 days 4
Critical Duration Requirement
The full 10-day course is mandatory to achieve maximal pharyngeal eradication and prevent acute rheumatic fever—shortening the course even by a few days dramatically increases treatment failure rates 1, 4. Five-day courses of standard-dose penicillin are less effective (OR 0.43; 95% CI 0.23-0.82) 1.
Treatment for Non-Anaphylactic Penicillin/Amoxicillin Allergy
First-generation cephalosporins are the preferred first-line alternatives for patients with non-immediate reactions (delayed rash, mild GI upset), as cross-reactivity risk is only 0.1% 2, 5:
- Cephalexin: 500 mg orally every 12 hours for 10 days (adults) or 20 mg/kg/dose twice daily for 10 days (children, max 500 mg/dose) 2, 5
- Cefadroxil: 30 mg/kg once daily for 10 days (children) 2
These agents have strong, high-quality evidence supporting superior bacteriologic eradication compared to penicillin (OR 1.47; 95% CI 1.06-2.03) 1, though clinical differences are small 1.
Treatment for Immediate/Anaphylactic Penicillin Allergy
Patients with immediate hypersensitivity (anaphylaxis, angioedema, respiratory distress, urticaria within 1 hour) must avoid ALL beta-lactam antibiotics including cephalosporins due to up to 10% cross-reactivity risk 1, 2.
Clindamycin: Preferred Choice
Clindamycin is the preferred alternative for immediate/anaphylactic penicillin allergy with strong, moderate-quality evidence 2, 5:
- Adults: 300 mg orally three times daily for 10 days 1, 2, 5
- Children: 7 mg/kg/dose three times daily for 10 days (max 300 mg/dose) 1, 2
Clindamycin has unique advantages: approximately 1% resistance rate in the United States, demonstrated high efficacy even in chronic carriers who failed penicillin, and superior eradication rates in recurrent infections 1, 2, 5. It is particularly effective for patients with recurrent tonsillitis 2, 5.
Macrolides: Acceptable Alternatives with Caveats
Azithromycin is the most convenient macrolide option requiring only 5 days due to prolonged tissue half-life 1, 2:
Clarithromycin requires the full 10-day course 2:
- Adults: 250 mg twice daily for 10 days 1, 2
- Children: 7.5 mg/kg/dose twice daily for 10 days (max 250 mg/dose) 1, 2
Erythromycin is less preferred due to high gastrointestinal side effects 2, 6, 7:
- Adults: 250 mg four times daily or 500 mg twice daily for 10 days 6
- Children: 20-40 mg/kg/day divided 2-4 times daily for 10 days 6
Critical Macrolide Limitations
Macrolide resistance among GAS is 5-8% in the United States and varies geographically—some areas have much higher rates 1, 2. Because of increasing resistance, short-course macrolides are not recommended as first-line alternatives 1. Clindamycin is more reliable than macrolides when beta-lactams cannot be used due to its lower resistance rate (1% vs 5-8%) 2, 5.
Age and Weight Considerations
For children <3 months: Maximum dose is 30 mg/kg/day of amoxicillin divided every 12 hours due to incompletely developed renal function 4. The 10-day course for GAS infections still applies 4.
For children ≥3 months and <40 kg: Use weight-based dosing as outlined above 4.
For patients ≥40 kg: Use adult dosing regimens 4.
Common Pitfalls to Avoid
Never prescribe cephalosporins to patients with immediate/anaphylactic penicillin reactions—the 10% cross-reactivity risk makes all beta-lactams unsafe in this group 1, 2
Never shorten antibiotic courses below 10 days (except azithromycin's 5-day regimen)—this increases treatment failure and rheumatic fever risk 1
Never use trimethoprim-sulfamethoxazole (Bactrim) for strep throat—it has 50% resistance rates and is not effective against GAS 2
Never prescribe antibiotics without confirming bacterial infection—viral tonsillitis requires only supportive care with acetaminophen or NSAIDs 3
Never assume all "penicillin-allergic" patients need non-beta-lactam antibiotics—distinguish between immediate and non-immediate reactions, as most can safely receive first-generation cephalosporins 2, 5
Never ignore local macrolide resistance patterns—in areas where resistance exceeds 10%, avoid macrolides entirely 2
Adjunctive Therapy
For moderate to severe symptoms or high fever, use acetaminophen or NSAIDs (ibuprofen) 2, 3. Avoid aspirin in children due to Reye syndrome risk 2. Corticosteroids are not recommended 2.
Special Situations: Recurrent Tonsillitis
For patients with frequent recurrent episodes, distinguish between true recurrent infections versus chronic carriers experiencing intercurrent viral infections 1, 5. Chronic carriers generally do not require treatment unless special circumstances exist (community outbreak, family history of rheumatic fever, excessive family anxiety) 1.
If treatment of chronic carriage is indicated, clindamycin 20-30 mg/kg/day in 3 doses for 10 days (max 300 mg/dose) is most effective 1, 5. Alternative regimens include penicillin plus rifampin or amoxicillin-clavulanate 1.
Consider tonsillectomy for recurrent membranous tonsillitis meeting Paradise criteria: 7+ documented episodes in 1 year, or 5+ episodes/year for 2 years, or 3+ episodes/year for 3 years 3.