Amoxicillin Dosing for Acute Otitis Media
For children ≥6 months with acute otitis media, prescribe high-dose amoxicillin 80–90 mg/kg/day divided twice daily; for adults, use 1.5–4 g/day divided twice or three times daily. 1, 2
Pediatric Dosing (≥6 months to <40 kg)
Standard High-Dose Regimen
- Administer 80–90 mg/kg/day divided into two doses (every 12 hours) for most children with uncomplicated AOM. 1, 2, 3
- Maximum single dose is 2 grams. 1
- Treatment duration: 10 days for children <2 years; 7 days for children 2–5 years with mild-moderate disease; 5–7 days for children ≥6 years with mild-moderate disease. 1, 2
When to Use Amoxicillin-Clavulanate Instead
Switch to amoxicillin-clavulanate (90 mg/kg/day amoxicillin + 6.4 mg/kg/day clavulanate, divided BID) when:
- The child received amoxicillin within the prior 30 days 1, 2, 3
- Concurrent purulent conjunctivitis is present (suggests H. influenzae) 1, 2, 3
- The child attends daycare or lives in an area with high prevalence of β-lactamase-producing organisms 1, 2
- Initial amoxicillin therapy fails at 48–72 hours 1, 2
The 14:1 amoxicillin-to-clavulanate ratio formulation causes significantly less diarrhea (10–13%) than older 7:1 formulations while maintaining efficacy. 1, 3
Infants <6 Months
- Maximum dose is 30 mg/kg/day divided every 12 hours due to immature renal function. 4
- Always treat for 10 days in this age group. 4
Adult Dosing (≥40 kg)
Standard Regimen
- Mild-moderate disease: 500 mg every 12 hours OR 250 mg every 8 hours. 4
- Severe disease or recent antibiotic exposure (within 4–6 weeks): 875 mg every 12 hours OR 500 mg every 8 hours. 5, 4
High-Dose for Resistant Organisms
- For adults with moderate disease, recent antibiotic use, or high local resistance: amoxicillin-clavulanate 2000 mg/125 mg twice daily (equivalent to 4 g/250 mg per day total). 5, 1
Treatment Duration
- Adults can be treated with 5–7 days for uncomplicated cases, extrapolated from sinusitis data showing equivalent efficacy with fewer side effects. 1
Penicillin-Allergic Patients
Non-Type I (Non-Anaphylactic) Allergy
- Cefdinir 14 mg/kg/day once daily (preferred for convenience and tolerability) is the first-choice alternative. 1, 2
- Alternatives: cefuroxime 30 mg/kg/day divided BID or cefpodoxime 10 mg/kg/day divided BID. 1, 2
- Cross-reactivity between penicillins and second/third-generation cephalosporins is negligible (≈0.1%), far lower than the historically cited 10%. 1, 2
Type I (Anaphylactic) Allergy
- All cephalosporins are contraindicated. 1
- Use macrolides (azithromycin, clarithromycin) as the only safe oral option, though bacterial failure rates are 20–25% due to pneumococcal resistance >40%. 1, 2
Treatment Failure Protocol
- Reassess at 48–72 hours if symptoms worsen or fail to improve. 1, 2
- If amoxicillin fails → switch to amoxicillin-clavulanate 90 mg/kg/day. 1, 2, 3
- If amoxicillin-clavulanate fails → administer ceftriaxone 50 mg/kg IM/IV once daily for 3 consecutive days (superior to single-dose regimen). 1, 2
- After multiple failures → perform tympanocentesis with culture and susceptibility testing. 1, 2
Disease Severity Stratification
Severe AOM (Requires Immediate Antibiotics)
- Moderate-to-severe otalgia 1, 2
- Otalgia persisting ≥48 hours 1, 2
- Fever ≥39°C (102.2°F) 1, 2
- Bilateral AOM in children 6–23 months 1, 2
Non-Severe AOM (Observation May Be Appropriate)
- Children ≥24 months with mild otalgia <48 hours and temperature <39°C can be observed with reliable 48–72 hour follow-up. 1, 2
- Provide a safety-net prescription to be filled only if symptoms worsen or fail to improve. 1, 2
Pharmacodynamic Rationale for High-Dose Therapy
- High-dose amoxicillin achieves 92% eradication of S. pneumoniae (including penicillin-nonsusceptible strains with MIC ≤2.0 μg/mL), compared to 83% with standard dosing. 1, 3
- It provides 84% eradication of β-lactamase-negative H. influenzae but only 62% for β-lactamase-positive strains, which is why amoxicillin-clavulanate is preferred when β-lactamase producers are suspected. 1
- Amoxicillin-clavulanate achieves 96% eradication of S. pneumoniae by days 4–6, significantly superior to azithromycin. 1, 3
Local Resistance Considerations
- In communities where <5% of *S. pneumoniae* isolates are nonsusceptible to standard-dose amoxicillin (MIC >2 μg/mL), standard dosing (40–45 mg/kg/day) may be acceptable for low-risk children. 6
- However, national guidelines universally recommend high-dose therapy because resistance patterns vary geographically and individual risk cannot be predicted reliably. 1, 2
- Children attending daycare have 2.6 times higher odds of carrying nonsusceptible S. pneumoniae (29% vs 14%). 6
Critical Pitfalls to Avoid
- Do not use azithromycin or other macrolides as first-line therapy; pneumococcal macrolide resistance exceeds 40% in the U.S., resulting in 20–25% bacterial failure rates. 1, 2
- Do not use trimethoprim-sulfamethoxazole for treatment failures; resistance is substantial (≈50% for S. pneumoniae). 1, 2
- Do not prescribe cephalosporins to patients with documented Type I (IgE-mediated) penicillin allergy due to cross-reactivity risk. 1, 2
- Do not extend the duration of a failing antibiotic; switch to a different agent with broader coverage instead. 1, 2
- Antibiotics provide no symptomatic relief in the first 24 hours; always initiate weight-based acetaminophen or ibuprofen immediately for pain control. 1, 2
- Isolated tympanic membrane redness without middle ear effusion does not constitute AOM and should not be treated with antibiotics. 1, 2
Administration and Compliance
- Administer amoxicillin at the start of a meal to minimize gastrointestinal intolerance. 4
- Twice-daily dosing is as effective as three-times-daily dosing and improves compliance. 1, 7
- For oral suspension, shake well before each use; refrigeration is preferable but not required; discard unused portion after 14 days. 4