Amoxicillin Dosing for Streptococcal Pharyngitis and Acute Otitis Media

Streptococcal Pharyngitis (Strep Throat)

Once‑daily amoxicillin 50 mg/kg (maximum 1000 mg) for 10 days provides superior adherence while achieving efficacy equivalent to multiple‑daily regimens. Strong, high‑quality evidence from the IDSA guideline. 1
Once‑daily regimen improves adherence and palatability in children. Supported by IDSA data. 1
Twice‑daily alternative (25 mg/kg every 12 h for 10 days, total ≈950 mg/day) may be used when once‑daily dosing is not feasible. 3

A full 10‑day course is mandatory to prevent acute rheumatic fever, regardless of early symptom resolution. High‑quality IDSA recommendation. [1][4]2
Clinical improvement within 24–48 h does not justify shortening therapy. IDSA emphasizes maintaining the 10‑day duration. [1][3]

Do not exceed 1000 mg per day for once‑daily dosing or 500 mg per individual dose for twice‑daily regimens. 3

Non‑anaphylactic allergy: First‑generation cephalosporin (cephalexin) 500 mg twice daily in adults; 20 mg/kg per dose (max 500 mg) twice daily in children. Guideline endorsed. [4][2]3
Non‑anaphylactic allergy: Clarithromycin for 10 days. [4][2]
Non‑anaphylactic allergy: Azithromycin 12 mg/kg once daily (max 500 mg) for 5 days. [4][2]3
Anaphylactic allergy: Clindamycin 7 mg/kg (max 300 mg) three times daily for 10 days. [4][2]3
Anaphylactic allergy: Azithromycin 12 mg/kg once daily (max 500 mg) for 5 days. [4][2]3

Do not avoid first‑generation cephalosporins in non‑anaphylactic penicillin allergy; cross‑reactivity is minimal and guidelines explicitly endorse their use. 3
Do not prescribe macrolides (azithromycin, clarithromycin) as first‑line therapy because regional resistance rates are 5–8 % in most U.S. areas. 3
Do not shorten the 10‑day course even if symptoms resolve early; this is essential for rheumatic fever prevention. [1][4]2

Children < 2 years or with severe symptoms: Amoxicillin 80–90 mg/kg/day divided twice daily (≈45 mg/kg per dose) for 10 days. Based on AAP guideline. 5
Children 2–5 years with mild‑moderate disease: Amoxicillin 40–45 mg/kg/day (e.g., 25 mg/kg/day divided q12 h or 20 mg/kg/day divided q8 h) for 7 days. AAP recommendation. 5
Children ≥ 6 years with mild‑moderate disease: Same dosing as above but 10 days recommended. 5

Age / Weight	Severity	Amoxicillin Dose (per day)	Division	Duration
≥ 3 months, < 40 kg	Mild/Moderate (age ≥ 2 y)	25 mg/kg (or 20 mg/kg)	q12 h or q8 h	7 days (2‑5 y) or 10 days (≥ 6 y)
≥ 3 months, < 40 kg	Severe or age < 2 y	45 mg/kg (or 40 mg/kg)	q12 h or q8 h	10 days
≥ 40 kg (adults & larger children)	Mild/Moderate	500 mg q12 h or 250 mg q8 h	–	–
≥ 40 kg	Severe	875 mg q12 h or 500 mg q8 h	–	–

All pediatric dosing rows are derived from the AAP guideline. 5

Children < 2 years or with severe symptoms: 10‑day course is mandatory. 5
Children 2–5 years with mild‑moderate disease: 7‑day course is acceptable. 5
Children ≥ 6 years with mild‑moderate disease: 10‑day course is recommended. 5

High‑dose amoxicillin (80–90 mg/kg/day) is recommended to overcome penicillin‑nonsusceptible Streptococcus pneumoniae. AAP guideline. 5

Do not use standard‑dose amoxicillin (40–45 mg/kg/day) as first‑line in regions with resistant S. pneumoniae prevalence. 5
Do not schedule routine follow‑up at 10–14 days unless the child has severe disease, recurrent AOM, or parental concern. 5
Do not treat persistent middle‑ear effusion with antibiotics; 60–70 % of children have effusion at 2 weeks post‑treatment, which does not represent acute otitis media. 5
Do not shorten therapy to < 10 days in children < 2 years; multiple studies support the standard 10‑day regimen for this age group. 5