What is the appropriate treatment for acute pharyngitis in a 5‑year‑old child weighing about 32 lb with a known amoxicillin allergy?

Treatment of Pharyngitis in a 5-Year-Old with Amoxicillin Allergy

For a 5-year-old child (32 lb/14.5 kg) with acute pharyngitis and amoxicillin allergy, prescribe azithromycin 145 mg (10 mg/kg) on day 1, followed by 72.5 mg (5 mg/kg) once daily on days 2–5, for a total 5-day course. 1

Diagnostic Confirmation Required

Before prescribing antibiotics, confirm Group A Streptococcal (GAS) pharyngitis through testing:

• Perform a rapid antigen detection test (RADT) in all children with suspected bacterial pharyngitis 1
• Back up negative RADT results with throat culture in children and adolescents because the sensitivity of rapid tests may miss true infections 1
• Do not treat viral pharyngitis with antibiotics—clinical features suggesting viral etiology include cough, rhinorrhea, hoarseness, and oral ulcers 1

First-Line Treatment for Penicillin-Allergic Patients

The 2012 IDSA guideline provides clear alternatives for penicillin-allergic children:

For Non-Anaphylactic Penicillin Allergy

• First-generation cephalosporins for 10 days are appropriate if the allergy history does not suggest Type I hypersensitivity (anaphylaxis, urticaria, angioedema) 1
• Cross-reactivity between penicillins and cephalosporins is lower than historically reported, making cephalosporins generally safe for non-severe reactions 2

For Type I Hypersensitivity or Uncertain Allergy Type

Macrolide antibiotics are the recommended alternative:

• Azithromycin: 10 mg/kg (maximum 500 mg) on day 1, then 5 mg/kg (maximum 250 mg) once daily on days 2–5 1
• Clarithromycin: 15 mg/kg/day in 2 divided doses (maximum 1 g/day) for 10 days 1
• Clindamycin for 10 days is another acceptable option 1

For this 32-pound (14.5 kg) child, azithromycin dosing would be:

• Day 1: 145 mg
• Days 2–5: 72.5 mg once daily

Why Azithromycin Is Preferred Among Macrolides

• Five-day course improves adherence compared to 10-day regimens with clarithromycin or clindamycin 1
• Once-daily dosing is more convenient for pediatric patients 3
• FDA-approved for pharyngitis/tonsillitis with documented efficacy: 95% bacteriologic eradication at Day 14 and 77% at Day 30 in pediatric streptococcal pharyngitis studies 3
• Lower gastrointestinal side effect profile (6% diarrhea, 6% vomiting) compared to penicillin V in head-to-head trials 3

Critical Limitations of Macrolide Therapy

Macrolides have limited effectiveness against major respiratory pathogens due to resistance:

• Bacterial failure rates of 20–25% are possible with macrolides for respiratory infections 1
• Macrolides should be reserved exclusively for patients with documented penicillin allergy—they are not appropriate first-line agents 1, 4
• The 2004 rhinosinusitis guideline explicitly states macrolides "do not provide optimal coverage" for respiratory pathogens 1

Pain Management Is Mandatory

• Prescribe acetaminophen or ibuprofen in age-appropriate doses for symptom relief during the first 24–48 hours 1
• Avoid aspirin in children due to Reye syndrome risk 1
• Pain control should be addressed regardless of antibiotic therapy 1

When NOT to Treat

• Do not test or treat children under 3 years old unless special risk factors exist (e.g., older sibling with documented GAS infection), because acute rheumatic fever is rare and classic streptococcal pharyngitis is uncommon in this age group 1
• Do not treat asymptomatic household contacts of patients with streptococcal pharyngitis 1
• Do not perform follow-up cultures or RADTs after treatment completion unless special circumstances exist 1

Key Pitfalls to Avoid

• Never use trimethoprim-sulfamethoxazole or erythromycin-sulfisoxazole for pharyngitis—resistance rates are substantial 1
• Distinguish true Type I hypersensitivity (anaphylaxis, urticaria) from other reactions like rash, which may tolerate cephalosporins 1
• Do not prescribe antibiotics empirically without confirming GAS infection through testing, as viral pharyngitis accounts for the majority of cases 1, 4
• Amoxicillin-clavulanate is not indicated for uncomplicated pharyngitis—the clavulanate component adds no benefit and increases side effects 4