Amoxicillin Dosing for Pneumonia in Adults

For adults with community-acquired pneumonia, amoxicillin should be dosed at 1 gram (1000 mg) orally three times daily (every 8 hours). 1, 2, 3

Dosing by Clinical Context

Amoxicillin 1 g orally every 8 hours is the first-line recommendation for otherwise healthy adults with community-acquired pneumonia 1, 2, 3
This high-dose regimen has demonstrated efficacy even against drug-resistant Streptococcus pneumoniae (DRSP) and provides adequate coverage despite lack of activity against atypical organisms 1
The FDA-approved dosing range for adults is 750-1750 mg/day in divided doses every 8-12 hours, but the 1 g every 8 hours regimen is specifically endorsed by major guidelines 4

Amoxicillin 1 g every 8 hours should be combined with a macrolide (azithromycin or clarithromycin) when patients have cardiopulmonary disease (COPD, heart failure), are age ≥65 years, or have other risk factors for resistant organisms 1, 2
Alternatively, amoxicillin-clavulanate 2000/125 mg twice daily can be used as the beta-lactam component in combination therapy, particularly when beta-lactamase-producing organisms (H. influenzae, M. catarrhalis) are suspected 1, 5
Monotherapy with a respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) is an alternative to combination therapy 1

Intravenous amoxicillin-clavulanate or other beta-lactams combined with a macrolide are recommended for non-ICU hospitalized patients 1, 2
The same 1 g every 8 hours dosing principle applies, though IV formulations may be used initially with transition to oral therapy once clinically stable 1

5-7 days of treatment is sufficient for most cases of community-acquired pneumonia in patients who demonstrate clinical improvement 1, 6
Studies demonstrate that 3-day courses can be effective in hospitalized patients who substantially improve after initial therapy, though 5-7 days remains the standard recommendation 6, 7
Treatment should not routinely exceed 8 days in responding patients 1
Clinical stability criteria (temperature normalization, respiratory rate <24/min, heart rate <100/min, systolic BP ≥90 mmHg, oxygen saturation ≥90%) can guide discontinuation of antibiotics 6

Avoid these common pitfalls:

Do not use standard-dose amoxicillin (250-500 mg three times daily) for pneumonia—this underdosing increases treatment failure risk and promotes resistance 1
Do not use amoxicillin monotherapy in patients with comorbidities without adding atypical coverage, as mixed infections with Mycoplasma or Chlamydophila are common 1, 2
Switch to a different antibiotic class if the patient received amoxicillin within the past 3 months to reduce resistance risk 1, 2
Avoid macrolide monotherapy in areas with pneumococcal macrolide resistance ≥25%, but amoxicillin remains effective 2, 3

Reduce dosing in severe renal impairment (GFR <30 mL/min) per FDA labeling, though specific pneumonia dosing adjustments are not well-defined in guidelines 4
No dose adjustment is needed for mild-moderate renal impairment when using the 1 g every 8 hours regimen 4

Do not use amoxicillin for suspected MRSA or Pseudomonas aeruginosa pneumonia—these require alternative coverage 1
Discontinue immediately if serious hypersensitivity reactions occur, including anaphylaxis or severe cutaneous adverse reactions 4
Consider alternative agents in patients with recent Clostridioides difficile infection, though amoxicillin has lower risk than broader-spectrum agents 4