Amoxicillin-Clavulanate Dosing and Duration for Pneumonia
For adults with community-acquired pneumonia, use amoxicillin-clavulanate 875-1000 mg/125 mg orally every 12 hours or 1.2 g IV every 8 hours for 5-7 days, stopping when afebrile for 48 hours and clinically stable. 1, 2
Adult Dosing by Severity
Low Severity (Outpatient, CRB-65 0-1)
- Oral: Amoxicillin-clavulanate 1-2 g every 12 hours 1
- Duration: 5-7 days if afebrile for 48 hours and clinically stable 1
- Clinical stability defined as: temperature ≤37.8°C, heart rate ≤100 bpm, respiratory rate ≤24/min, systolic BP ≥90 mmHg, oxygen saturation ≥90% 1
Moderate Severity (Non-ICU, CURB-65 2-3)
- IV: Amoxicillin-clavulanate 1.2 g every 8 hours 1
- Duration: 5-7 days 1
- Can transition to oral 875 mg/125 mg twice daily when clinically improving 3
Severe (ICU, CURB-65 4-5)
- IV: Amoxicillin-clavulanate 1.2 g every 8 hours PLUS a macrolide (azithromycin 500 mg daily or clarithromycin 500 mg every 12 hours) OR a respiratory fluoroquinolone 1
- Duration: 7 days 1
Pediatric Dosing
Children ≥3 Months
- High-dose regimen (preferred): 90 mg/kg/day of amoxicillin component divided into 2 doses (maximum 4000 mg/day) 4, 2
- This provides the 14:1 ratio formulation (90 mg/kg amoxicillin with 6.4 mg/kg clavulanate) 4
- Standard regimen: 45 mg/kg/day divided into 3 doses 4, 2
Infants <3 Months
- Dose: 30 mg/kg/day divided every 12 hours based on amoxicillin component 2
- Use 125 mg/31.25 mg per 5 mL suspension 2
Duration for Children
- 10 days for bacterial pneumonia 4
- High-dose therapy indicated for children <2 years, daycare attendance, recent antibiotic use, or moderate-to-severe illness 4
Special Populations
Elderly Patients
- Same dosing as adults: 1.2 g IV every 8 hours for moderate severity 3
- Renal adjustment required: 3
- CrCl 10-30 mL/min: 1.2 g IV every 12 hours
- CrCl <10 mL/min: 1.2 g IV every 24 hours
- Monitor renal function during treatment due to decreased clearance 3
Aspiration Pneumonia Risk
- Same dosing as standard pneumonia: 1-2 g orally every 12 hours or 1.2 g IV every 8 hours 1
- Amoxicillin-clavulanate provides adequate anaerobic coverage without additional metronidazole 1
Critical Pitfalls to Avoid
Do not substitute tablet strengths interchangeably. Two 250 mg/125 mg tablets ≠ one 500 mg/125 mg tablet because clavulanate content differs 2. This error leads to inadequate clavulanate dosing and treatment failure against β-lactamase producers.
Do not underdose pediatric patients. Using 45 mg/kg/day instead of 90 mg/kg/day when high-dose therapy is indicated results in treatment failure against penicillin-resistant S. pneumoniae 4. The high-dose regimen achieves concentrations adequate to overcome organisms with MICs up to 4 μg/mL 5, 6.
Do not extend duration beyond clinical stability. Continuing antibiotics after 48 hours of being afebrile and clinically stable increases adverse effects without benefit 1. The 5-7 day duration is supported by guideline evidence showing equivalent outcomes to longer courses 1.
Verify suspension concentration before calculating volume. The 125/31 mg per 5 mL suspension is NOT interchangeable with 250/62.5 mg per 5 mL suspension 4, 2. Dosing errors from this mistake are common and lead to either underdosing or excessive clavulanate-related diarrhea.
Administration Considerations
- Take at the start of meals to enhance clavulanate absorption and minimize GI intolerance 2
- The 14:1 ratio formulation (90/6.4 mg/kg/day) causes less diarrhea than other ratios while maintaining efficacy 4
- Assess therapeutic response after 2-3 days; fever should resolve within 2-4 days depending on etiology 3